Biocenoses differ in the species diversity of their constituent organisms.
The species structure of a biocenosis is understood as the diversity of species in it and the ratio of their numbers or biomass.
Species structure.
STRUCTURE OF BIOCENOSIS.
A biotope is a place of existence, or habitat of a biocenosis, and a biocenosis can be considered as a historically developed complex of living organisms, characteristic of a particular biotope.
A biotope is a section of territory with more or less homogeneous conditions, occupied by one or another community of living organisms (biocenosis).
In other words,
The branch of ecology that studies the patterns of formation of communities and the joint life of organisms in them is called synecology (biocenology).
Synecology arose relatively recently - at the beginning of the twentieth century.
The structure of a biocenosis is the relationship between different groups of organisms that differ in systematic position; according to the place they occupy in space; by the role they play in the community, or by another characteristic that is essential for understanding the patterns of functioning of a given biocenosis.
Distinguish species, spatial and ecological structure of the biocenosis.
Each specific biocenosis is characterized by a strictly defined species composition (structure).
In those biotopes where environmental conditions are close to optimal for life, extremely species-rich communities arise ( for example, biocenoses of tropical forests or coral reefs).
The biocenoses of the tundra or desert are extremely poor in species. This is explained by the fact that only a few species can adapt to such unfavorable environmental conditions as lack of heat or lack of moisture.
The relationship between living conditions and the number of species in a biocenosis is determined by the following principles:
1. The principle of diversity: The more diverse the living conditions within a biotope, the more species there are in a given biocenosis.
2. Principle of deviation of conditions: The more the conditions of existence within a biotope deviate from the norm (optimum), the poorer the biocenosis becomes in species and the more numerous each species becomes.
3. The principle of smooth changes in the environment: The more smoothly the environmental conditions in a biotope change and the longer it remains unchanged, the richer the biocenosis is in species and the more balanced and stable it is.
The practical significance of this principle is that the more and faster the transformation of nature and biotopes occurs, the more difficult it is for species to have time to adapt to this transformation, and therefore the species diversity of biocenoses becomes less
There is also a known pattern of changes in species diversity (Wallace’s rule): species diversity decreases as you move from south to north ( those. from the tropics towards high latitudes).
For example:
- in tropical rainforests there are up to 200 species of tree species per 1 hectare;
· The biocenosis of a pine forest in the temperate zone can include a maximum of 10 tree species per 1 hectare;
· in the north of the taiga region there are 2-5 species per 1 hectare.
The species diversity of biocenoses also depends on the duration of their existence and the history of each biocenosis.
- young, emerging communities, as a rule, have a smaller set of species than long-established, mature ones;
- biocenoses created by humans (vegetable gardens, orchards, fields, etc.) are usually poorer in species compared to similar natural biocenoses (forest, meadow, steppe)
In each community, a group of main, most numerous species can be distinguished
Species that predominate in numbers in a biocenosis are called dominant or dominant.
Dominant species occupy a leading, dominant position in the biocenosis.
For example, the appearance of a forest or steppe biocenosis is represented by one or more dominant plant species:
in an oak grove it is oak, in a pine forest it is pine, in the feather grass-fescue steppe it is feather grass and fescue..
Typically, terrestrial biocenoses are named by their dominant species:
* larch forest, coniferous forest (pine, spruce, fir), sphagnum swamp (sphagnum moss), feather-fescue steppe (feather grass and fescue).
Species that live off dominants are called predominants.
For example, in an oak forest, these are various insects, birds, and mouse-like rodents feeding on the oak tree.
Among the dominant species there are edificators are those species that, through their vital activity, create conditions for the life of the entire community to the greatest extent.
Let's consider the edificatory role of spruce and pine.
Spruce in the taiga zone forms dense, heavily shaded forests. Only plants adapted to conditions of strong shading, high air humidity, high soil acidity, etc. can live under its canopy. According to these factors, a specific animal population is formed in spruce forests.
Consequently, spruce in this case acts as a powerful edificator, determining a certain species composition of the biocenosis.
In pine forests the edificator is pine. But compared to spruce, it is a weaker edificator, since the pine forest is relatively light and has sparse trunks. Its species composition of plants and animals is much richer and more diverse than in the spruce forest. In pine forests there are even plants that can live outside the forest.
Edificatory species are found in almost any biocenosis:
* in sphagnum bogs - these are sphagnum mosses;
* In steppe biocenoses, feather grass serves as a powerful edificator.
In some cases, animals can also be edifiers:
* in the territories occupied by marmot colonies, it is their activity that mainly determines the nature of the landscape, microclimate and conditions for the growth of grasses.
However, the role of edificators in certain biocenoses is not absolute and depends on many factors:
* Thus, when a spruce forest is thinned, spruce may lose its functions as a powerful edificator, since this lightens the forest and other species are introduced into it, reducing the edificatory value of spruce;
* in a pine forest located on sphagnum bogs, pine also loses its edificatory value, as sphagnum mosses acquire it.
In addition to a relatively small number of dominant species, a biocenosis usually includes many small and even rare forms (minor species), which create its species richness, increase the diversity of biocenotic connections and serve as a reserve for the replenishment and replacement of dominants, i.e. give the biocenosis stability and ensure its functioning in different conditions.
Based on the relationships between species in populations, biocenoses are divided into complex and simple.
Complex biocenoses are biocenoses consisting of a large number of populations of different species of plants, animals and microorganisms, interconnected by various food and spatial relationships.
Complex biocenoses are the most resistant to adverse effects. The disappearance of a species does not significantly affect the organization of such biocenoses, since, if necessary, another species can replace the disappeared one.
In exceptionally complex biocenoses of tropical forests, outbreaks of mass reproduction of individual species are never observed.
For simple Tundra or desert biocenoses are characterized by a sharp increase or decrease in the number of animals, which have a significant impact on the vegetation cover.
This is explained by the fact that in a simplified biocenosis there are not enough species that, if necessary, could replace the main species and act, for example, as food for predators.
Teacher of chemistry, biology, ecology
GBOU secondary school No. 402.
BIOGECENOSIS
GRADE 10
Lesson learning objectives:
deepen knowledge about biogeocenosis;
introduce students to the properties of biogeocenosis;
Developmental goals of the lesson:
develop in students the ability to highlight the main, essential things in educational material, compare, generalize and systematize, establish cause-and-effect relationships;
promote the development of strong-willed and emotional qualities of the individual;
Pay special attention to developing interest in the subject and speech of students.
Educational objectives of the lesson:
promote the formation of worldview ideas:materiality of the world;
continuity of the cognition process.
Form of the educational process:
cool lesson.Lesson type: lesson in gaining new knowledge.
Lesson structure:
Org. moment
1 min.
Update
2 minutes.
Goal setting
1 min.
Learning new material
25min.
reflection
10 min
1 min.
Equipment:
Board;
Projector;
Computer;
Handout;
Method of providing information: Textual, structural-logical, information-technological.
Teaching method: partial-search
Technology: Personality-oriented.
During the classes.
Stage.
Teacher's activities.
Student activities.
Organizing time.
Greetings.
Gets the children ready for the lesson.
Getting ready for the lesson.
Updating.
What is biocenosis?
How is the prefix “GEO” translated?
Let's combine the prefix “GEO” and the concept of BIOCENOSIS.
The phrases continue.
Answer questions.
Goal setting.
Today in class we will look at the concept of BIOGEOCENOSIS.
Write down the topic of the lesson: BIOGECENS.
Learning new material.
In biology, three concepts that are similar in meaning are used:
1. Biogeocenosis- a system of a community of living organisms (biota) and its biotic environment on a limited area of the earth’s surface with homogeneous conditions (biotope)
2. Biogeocenosis- biocenosis, which is considered in interaction with abiotic factors influencing it and, in turn, changing under its influence. Biocenosis is synonymous with community, and the concept of ecosystem is also close to it.
3. Ecosystem- a group of organisms of different species interconnected by the cycle of substances.
Every biogeocenosis is an ecosystem, but not every ecosystem is a biogeocenosis - Justify this phrase.
To characterize biogeocenosis, two similar concepts are used: biotope and ecotope (factors of inanimate nature: climate, soil).Define these terms.
Properties of biogeocenosis
1. natural, historically established system
2. a system capable of self-regulation and maintaining its composition at a certain constant level
3. characterized by the circulation of substances
4. an open system for the entry and exit of energy, the main source of which is the Sun
Main indicators of biogeocenosis
1. Species composition - the number of species living in the biogeocenosis.
2. Species diversity - the number of species living in a biogeocenosis per unit area or volume.
In most cases, species composition and species diversity do not coincide quantitatively, and species diversity directly depends on the study area.
Why?
3. Biomass - the number of organisms of a biogeocenosis, expressed in units of mass. Most often, biomass is divided into:
A. biomass producers
b. biomass of consumers
V. biomass of decomposers
Define: Who are producers, decomposers and consumers?
4. sufficiency of living space, that is, such a volume or area that provides one organism with all the resources it needs.
5. richness of species composition. The richer it is, the more stable the food chain and, consequently, the circulation of substances.
6. diversity of interactions between species, which also maintain the strength of trophic relationships.
7. environment-forming properties of species, that is, the participation of species in the synthesis or oxidation of substances.
8.direction of anthropogenic impact
Draw a conclusion based on the properties of biogeocenosis.
The joint life of organisms in a biogeocenosis is regulated by five types of biogeocenotic connections:
Define each type of biogeocenosis and provide examples.
Give examples with justifications for each concept.
Justify the phrase
Define the terms:
Biotope - this is the territory occupied by a biogeocenosis.
Ecotop - this is a biotope that is influenced by organisms from other biogeocenoses.
Write it down in a notebook.
Discuss the material with the teacher and ask questions.
They answer the question.
Answer the question:
Producers - organisms, capableTophoto- orchemosynthesisAndbeingVfood. chainsfirstlink, creatororganic. V- Vfrominorganic, T. e. Allautotrophicorganisms. Consumers - organisms, beingVtrophicchainsconsumersorganicsubstances. Decomposers - Organisms, decomposingdeadorganicsubstanceAndtransforminghisVinorganic, employeefoodothersorganisms.
Summarize the properties of biogeocenosis:
Thus, the mechanisms ensure the existence of unchanging biogeocenoses, which are called stable. A stable biogeocenosis that exists for a long time is called climax. There are few stable biogeocenoses in nature; stable ones are more common - changing biogeocenoses, but capable, thanks to self-regulation, of returning to their original, starting position.
Listen and write down the material in a notebook.
Give definitions and give examples.
Reflection.
Let's summarize today's lesson:
Run a test run:
1. Autotrophic organisms include
B) tinder fungi
B) blood-sucking insects
D) red algae
2. The stability and integrity of biogeocenosis does not depend on
A) geological changes in the Earth's crust
B) diversity of species composition
B) seasonal climate changes
D) flow of energy and matter
3. Self-regulation in biogeocenosis is manifested in the fact that
A) species reproduce intensively
B) the number of individuals changes
C) some species are not completely destroyed by others
D) the population size of certain species is increasing
4. A reservoir is considered a biogeocenosis, since the species living in it
A) located in one tier
B) power chains are formed
B) belong to the same kingdom
D) are not related to each other
5. The adaptability of plants to living together in the forest biogeocenosis is manifested in
A) increased competition between species
B) tiered arrangement
B) increasing leaf surface
D) modification of root systems
The test work is discussed and the correct answers are given..
Solve the test work.
Carry out a self-check.
Homework
Par….., Question…. Page…..
Run a test run:
1. A meadow is a more stable ecosystem than a wheat field, since it
A) there are producers
B) more fertile soil
C) there are more species
D) there are no predators
2. An example of biogeocenosis is the collection
A) plants grown in a botanical garden
B) oak trees and shrubs
C) all organisms living in the swamp
D) birds and mammals of the spruce forest
3. The greatest diversity of animal populations and species is characteristic of the biocenosis
A) oak forests
B) pine forest
B) orchard
D) tundra
4. The continuous movement of carbon, nitrogen and other elements in biogeocenoses is carried out largely due to
A) the action of abiotic factors
B) vital activity of organisms
B) the influence of climatic factors
D) volcanic activity
5. The ecosystem becomes more stable when
A) increasing species diversity
B) the presence of various power circuits
B) closed cycle of substances
D) disruption of the circulation of substances.
Write it down in a notebook.
114. The greatest diversity of plant and animal species is characteristic of biocenosis
1. tundra;
3. tropical forest +
4. forest-steppe
115. Ecosystem productivity (based on the formation of dry matter biomass) from the equator to the poles:
1. decreases +
2. remains unchanged;
3. increases;
4. first decreases and then increases again
5. first increases and then decreases
116. A large ecological group of aquatic organisms with the ability to move regardless of water currents:
2. plankton
3. nekton +
4. neuston
5. periphyton
117. Large ecological group of aquatic organisms localized at the bottom
1. plankton
2. periphyton
3. neuston
4. benthos +
118. A large ecological group of aquatic organisms that live freely in the water column and passively move through it
1. plankton +
2. periphyton
3. neuston
119. A large ecological group of aquatic organisms attached to aquatic plants
1. plankton
2. periphyton +
3. neuston
120. Ecological group of aquatic organisms living near the surface of the water, on the border of the aquatic and air environments:
1. plankton
2. periphyton
3. neuston +
121. Freshwater ecosystems formed in stagnant bodies of water
1. wetlands
2. lotic
3. lake
4. lentic +
5. eutrophic
122. Freshwater ecosystems formed in flowing waters
1. wetlands
2. lotic +
3. lake
4. lentic
5. eutrophic
123. The main edifier of communities in the tundra is
1. lichens +
3. shrubs
5. dwarf trees
124. Species that determine the structure and character of communities in biocenoses, playing an environment-forming role
1. dominants
2. edifiers +
3. subdominants
4. Assectators
5. violents
125. Under certain conditions, simple tundra biocenoses are characterized by
1. outbreaks of mass reproduction of certain species +
2. very small fluctuations in the numbers of individual species
3. outbreaks of mass reproduction of individual species are never observed
4. smooth rises in the number of species
5. Smooth declines in species numbers
126. The main condition for the sustainability of ecosystems is
1. the presence of formed fertile soil
2. closed ecosystem
3. presence of large herbivores
4. constant circulation of substances and energy flow +
5. high level of biodiversity
127. The scientist who proposed the term biogeocenosis
1. V.N.Sukachev +
2. V.I. Vernadsky
3. Dokuchaev
5. Charles Darwin
128. A set of environmental factors influencing the composition and structure of biocenoses
1. phytocenosis
2. edaphoto
3. climatotop
4. landscape
5. biotope +
129. Concept characterizing the position of a species in a biocenosis, expressed in the features of geographic localization, relation to environmental factors and functional role
1. ecological niche +
2. life form
3. dominance system
4. adaptation
5. life strategy
130. Similar morpho-ecological groups of different species of living organisms, with varying degrees of relatedness, expressing the type of adaptation to similar environmental conditions that arises as a result of convergent adaptation:
1. ecological niche
2. life form +
3. dominance system
4. adaptation
5. life strategy
131. The stability of an ecosystem as its complexity increases, as a rule:
1. varies depending on the nature of the relationships between organisms
2. does not change
3. increases +
4. decreases
5. does not depend on the degree of complexity
132. The importance of wetlands lies in the fact that these ecosystems are capable of...
1. regulate the temperature regime of ecotopes
2. produce mushrooms
3. produce cranberries and lingonberries
4. regulate the water regime of the territory +
5. produce peat
133. The most complex tropical rain forest ecosystems are characterized by:
1. high level diversity and low number of species +
2. high level of diversity and high number of species
3. low level of diversity and low number of species
4. low level of diversity and high number of species
5. high level of diversity and changing abundance of species
134. The highest rate of processing of dead organic matter by decomposer organisms is observed in ecosystems:
2. tropical rainforests +
3. boreal coniferous forests
5. Savannah
135. The abundance of large ungulate phytophages is characteristic of ecosystems
2. tropical rainforests
3. boreal coniferous forests
5. savannas +
136. The totality of all connections between a species and its habitat that ensure the existence and reproduction of individuals of a given species in nature are:
1. biocenosis +
3. edaphoto
4. climate control
5. competitive environment
137. At the consumer level, flows of living organic matter transferred different groups consumers follow the following chains:
1. savings
2. decomposition
3. transformation
4. eating +
5. synthesis
138. At the level of consumers, the flows of dead organic matter transferred to different groups of consumers follow the following chains:
1. savings
2. expansions +
3. transformation
4. eating
5. synthesis
139. When transferring organic matter to different groups of consumers, it is divided into two streams:
1. accumulation and decomposition
2. decomposition and transformation
3. transformation and synthesis
4. eating and decomposition +
5. synthesis and accumulation
140. More complete use of resources at each trophic level of the biocenosis is ensured by:
1. increase in the number of individual species
2. increasing the number of species +
3. increase in the number of all species
4. cyclical changes in numbers
5. increased predation
141. The amount of biomass and associated energy during each transition from one trophic level to another is about:
142. As you ascend through trophic levels, the total biomass, production, energy and number of individuals change:
1. progressively increase
2. increases during the transition from producers to consumers, and then decreases
3. the direction of decrease or increase changes cyclically depending on external factors
4. progressively decrease +
5. remain constant
143. The most important mechanism for maintaining the integrity and functional stability of biocenoses is:
abundance and diversity of species composition +
increased competition
interaction of all types at all levels
reduction of competition and species composition
constancy of species composition and reduction of competition
144. The sequence of trophic relationships, the end result of which is the mineralization of organic matter:
eating chains
transformation chains
decomposition chains +
mineralization chains
decomposer chains
145. The sequence of trophic relationships during which the synthesis and transformation of organic matter occurs:
1. eating chains +
2. transformation chains
3. decomposition chains
4. Mineralization chains
5. chain synthesis
146. The elementary structural and functional unit of the biosphere is:
biogeocenosis +
phytocenosis
communities of living organisms
147. Areas of the world's oceans, the high productivity of which is due to upward flows of water from the bottom to the surface
sargassum
rift
convention areas
upwelling +
148. Areas of the world’s oceans whose high productivity is due to the presence of fields of floating brown algae:
1. sargassum +
2. rift
3. Conventional areas
4. upwelling
5. reef
149. Areas of high biological diversity in the oceans, localized around hot springs on fractures in the oceanic crust and based on primary production supplied by chemotrophic organisms:
sargassum
abyssal rift
shelf
upwelling
reef +
150. Bottom concentrations of biodiversity at great depths of the ocean owe their existence to vital activity
algae
coral polyps
mollusks and echinoderms
chemotrophic bacteria +
151.The factor determining the geographical distribution in the oceans of areas of concentrations of living matter and high productivity around coral reefs is:
1. temperature not less than 20 o +
2. depth no more than 50 m
3. water clarity
4. water salinity
152. Areas of high productivity in the world’s oceans, in the communities of which there are no photosynthetic organisms:
sargassum condensation
abyssal rift +
shelf concentrations
upwelling concentrations
reef concentrations
153. The most productive fishing areas of the world's oceans, providing about 20% of the world's fisheries, are the areas:
upwelling +
abyssal rift
shelf
sargassum fields
coral reefs
154. Ecological area of the ocean coast, located above the water level at high tide, but exposed to ocean waters during storms and surges:
2. littoral
3. abyssal
4. supralittoral +
5. sublittoral
155. Ecological area of the ocean floor located in the zone between the water levels at the highest tide and the lowest ebb:
A) batial
B) littoral +
C) abyssal
D) supralittoral
E) sublittoral
156. Ecological area of the ocean floor, located in the zone from the water level at the lowest ebb to depths of 200 m:
A) abyssal
B) littoral
C) bathyal
D) supralittoral
E) sublittoral +
157. Ecological area of the ocean floor, located on continental slopes at depths of 200-2000 m:
A) batial +
B) littoral
C) abyssal
D) supralittoral
E) sublittoral
158. Ecological area of the ocean floor at depths exceeding 2000 m:
A) batial
B) littoral
C) abyssal +
D) supralittoral
E) sublittoral
159. Ecological groups of marine organisms - nekton, plankton, neuston and pleiston are characteristic of communities:
A) littoral
B) bathyals
C) abyssals
D) pelagial +
E) sublittoral
160. A community, which includes a phytocenosis, zoocenosis and microbiocenosis, having certain spatial boundaries, appearance and structure:
A) biocenosis +
E) biogeocenosis
161. The basis of most terrestrial biocenoses, which determines their appearance, structure and certain boundaries, is:
A) zoocenosis
C) edaphotope
D) microbiocenosis
E) phytocenosis +
162. The primary habitat of living organisms, formed by a combination of soil and climatic factors:
A) biotope
B) ecotop +
C) edaphotope
D) climate control
163. Secondary habitat formed as a result of the active influence of living organisms on the primary habitat:
A) biotope +
C) edaphotope
D) climate control
164. In steppe biocenoses, soil formation is dominated by the following processes:
A) mineralization
B) nitrification
C) humification +
D) denitrification
E) ammonification
165. The key factor in the formation of steppe biogeocenoses, which determines the characteristics of the cycle of nutrients, is:
A) temperature
B) level of solar radiation
C) seasonality of precipitation
D) soil moisture +
E) temperature contrast
166. Among the life forms of plants of steppe biogeocenoses, the most characteristic are:
A) bushes
B) subshrubs
C) ephemera
D) turf grasses +
E) rhizomatous cereals
167. The most characteristic features of the vertical structure of the animal population of steppe ecosystems are:.
A) aboveground tier
B) tree layer
C) underground tier
D) tree-shrub layer
E) abundance of burrowers +
168. The colonial lifestyle of various species and groups of rodents is most typical in ecosystems:
A) boreal forests
C) deciduous forests
E) tropical rain forests
169. The vertical structure of steppe biocenoses lacks:
A) tree layer +
B) tree-shrub layer
C) shrub layer
D) underground level
E) herbaceous layer
170. In steppe ecosystems, the group of phytophagous animals is practically not represented:
A) frugivores +
B) seed-eaters
C) green eaters
D) rhizophages
E) seed-eaters and rhizophages
171. Steppe ecosystems are geographically localized:
A) in the tropical zone
B) in high latitudes
C) in the subtropical climate area
D) in inland regions of temperate latitudes +
E) in the mountains
172. The soil cover of steppe biogeocenoses is formed:
A) brown soils
B) gray soils
C) podzolic soils
D) chernozems
E) chernozems and chestnut soils +
173. The change of several aspects during the growing season is a pronounced feature of phytocenoses:
A) steppes +
B) tropical rain forests
D) boreal forests
E) deserts
174. Edificatory species among vertebrates in steppe ecosystems are:
A) ungulate mammals
B) carnivorous mammals
C) reptiles
D) amphibians
E) rodents +
175. An important group of vertebrate animals that contribute to maintaining the stability of steppe phytocenoses are:
B) rodents
C) ungulates +
D) carnivorous mammals
E) insectivorous mammals
176. Of the terrestrial vertebrate animals in steppe ecosystems, the worst represented are:
A) reptiles
B) amphibians +
C) mammals
E) carnivorous mammals
177. In the steppe ecosystems of Asia, with increasing aridity in the direction from north to south, the importance of life forms in phytocenoses increases:
A) subshrubs +
B) turf grasses
C) bushes
D) rhizomatous cereals
E) forbs
178. In accordance with the increase in the moisture gradient from south to north, changes in the phytocenoses of the Asian steppes are expressed
A) in a decrease in species richness and an increase in the importance of ephemera and ephemeroids
B) in increasing the importance of subshrubs
C) in reducing the importance of dense turf grasses
D) in increasing species richness and the number of forb species +
E) in increasing the species diversity of rhizome grasses and dwarf shrubs
179. The characteristic life forms of plants of tropical rain forests, which have received great development here, are:
A) epiphytes and lianas +
B) subshrubs
C) perennial herbs
D) bushes
E) trees
180. Frugivorous and insectivorous species of animal consumers predominate in ecosystems:
A) boreal forests
B) deciduous forests
C) tropical rain forests +
E) subtropical forests
181. Termites are the leading group of saprophages in ecosystems:
A) boreal forests
B) deserts
C) tropical rain forests
D) savannah +
E) subtropical forests
182. Amphibians that live mainly in the tree layer are typical for ecosystems:
A) boreal forests
B) deciduous forests
C) subtropical forests
183. Lianas and epiphytes are specific life forms of plants, the most common and characteristic:
A) in boreal forests
B) in deciduous forests
C) tropical rain forests +
D) in savannas
E) in subtropical forests
184. In the ecosystems of tropical rain forests among animals, according to the nature of trophic relationships, the following prevail:
A) frugivores and insectivores +
B) seed-eaters
C) green eaters
D) rhizophages
185. Birds that feed on nectar and are effective pollinators of flowering plants are characteristic of the following ecosystems:
A) gallery scaffolding
B) deciduous forests
C) subtropical forests
E) tropical rain forests +
186. Complex polydominant communities of plants and animals characterize ecosystems:
B) deciduous forests
C) subtropical forests
E) boreal forests
187. The absence of clearly defined tiers of phytocenoses and at the same time the high complexity of their structure characterizes the ecosystems:
A) gallery scaffolding
B) deciduous forests
C) subtropical forests
E) tropical rain forests +
188. Large mammals occupy a very small place among phytophages in ecosystems:
A) boreal forests
B) deciduous forests
C) subtropical forests
E) tropical rain forests +
189. The dynamics of animal numbers, characterized by smooth changes without sharp peaks and declines, distinguishes ecosystems:
A) tropical rain forests+
C) deserts
E) deciduous forests
190. Communities of tree layers absolutely dominate among all taxonomic groups of animals in ecosystems:
A) gallery scaffolding
B) deciduous forests
C) subtropical forests
E) tropical rain forests +
191. In the phytocenoses of tropical rain forests this layer is absent:
A) shrubby +
B) herbaceous plants
C) epiphytes
E) trees
192. Life forms of the tree layer represent more than 50% of mammal species living in ecosystems
A) boreal forests
B) deciduous forests
C) subtropical forests
E) tropical rain forests +
193. The number of tree species significantly exceeds the number of grass species in phytocenoses of ecosystems:
A) boreal forests
B) tropical rain forests +
C) subtropical forests
E) deciduous forests
194. Effective direct return of nutrients into cycles ensures high productivity of ecosystems:
A) boreal forests
B) deciduous forests
C) subtropical forests
E) tropical rain forests +
195. The main factors determining the possibility of the existence of tropical rain forest ecosystems are:
A) rich soils and a large number of precipitation
B) rich soils and high temperatures
C) constancy of temperatures and evenly distributed precipitation +
D) high temperatures and large amounts of precipitation
E) rich soils and constant temperatures
196. Low temperatures and a short growing season are the main limiting factors in ecosystems:
A) boreal forests
B) tundra +
D) deciduous forests
E) deserts
197. Snow is the most important edaphic factor influencing the functioning of ecosystems:
A) boreal forests
B) deciduous forests
C) deserts
198. The main edificators of plant communities in the tundra are:
B) shrubs
C) dwarf trees
E) lichens +
199. Tundra phytocenoses have a very simple structure, in which only a few tiers are distinguished:
200. The main phytophages in tundra ecosystems are
A) large ungulates
B) voles and lemmings +
E) insects
201. High productivity of primary production of tundra phytocenoses is ensured by:
A) rich soils
B) optimal temperature conditions
C) a wide variety of producers
D) long summer photoperiods +
E) abundance of moisture
202. Low levels of diversity and high numbers of animal populations are a characteristic feature of ecosystems:
A) boreal forests
B) deciduous forests
C) subtropical forests
203. The simplest structure of the fauna of terrestrial vertebrates, including only terrestrial life forms, is characteristic of ecosystems
A) boreal forests
B) deciduous forests
C) tundra +
204. In terms of biomass, among saprophagous animals of the soil-litter layer in the tundra, the first place is occupied by
A) earthworms +
B) nematodes
D) springtails
E) larvae of tipulid mosquitoes
205. Among vertebrate animals, the greatest diversity in the tundra is achieved by:
A) mammals
B) reptiles
C) freshwater fish
D) amphibians
206. The most common adaptation of vertebrate animals, which allowed them to adapt to living in extreme conditions of the tundra:
A) hibernation
B) seasonal migrations +
C) stocking feed
D) life under the snow
E) hibernation and food storage
207. Boreal coniferous forests are geographically localized:
A) in North America
B) in the southern latitudes of South America and Australia
C) in the northern latitudes of North America, Eurasia and the southern latitudes of South America and Australia
D) in the northern latitudes of North America and Eurasia +
E) in the northern latitudes of Eurasia
208. The moisture balance (the ratio of precipitation and evaporation) in boreal coniferous forests over most of the territory is characterized by:
A) excess precipitation +
B) equilibrium
C) excess evaporation
D) long-term fluctuations
E) cyclical changes
209. The main edificators in phytocenoses of boreal coniferous forests are:
A) small-leaved species
C) lichens
D) conifers +
E) herbaceous layer
210. The monodominant structure of phytocenoses is characteristic of ecosystems:
A) coniferous boreal forests +
B) deciduous forests
C) subtropical forests
D) gallery scaffolding
211. For the vertical structure of phytocenoses of boreal coniferous forests, the most characteristic number of tiers is:
212. In the ecosystems of boreal coniferous forests, among vertebrate animals, edificatory species include:
A) hibernators
B) migrating
C) storing coniferous seeds +
E) ungulates
213. The animal population of boreal coniferous forests has a vertical structure, the number of tiers in which is equal to:
214. Features of a lotic ecosystem include:
A) Presence of flow, high oxygen content, active exchange between
water and land. +
B) Weak exchange between water and land, the presence of a current.
D) Predominance of detrital food chains.
E) No water flow, high oxygen content.
215. The presence of soil-litter, ground, shrub and tree layers of the animal population is typical for ecosystems:
A) subtropical forests
B) deciduous forests
C) subtropical forests
D) gallery scaffolding
E) coniferous boreal forests +
216. The least productive ecosystems are located:
A) in savannas
B) in the tundra;
C) in coniferous forests;
D) in deserts; +
E) in the steppes;
217. Consistent change of biocenoses with a gradual directed change in environmental conditions is called:
A) adaptation
B) evolution +
C) succession
D) dynamism
E) trend
218. Biome common in the Arctic zone of the Earth:
A) savanna;
D) forest-steppe;
E) tundra. +
219. Relationships between organisms through which the transformation of matter and energy occurs in ecosystems:
A) trophic web;
B) food web;
C) trophic chain; +
D) trophic level;
E) trophic branch.
220. Autotrophic organisms include:
A) consumers;
B) producers; +
C) decomposers;
E) predators.
221. Reservoirs with an average level of primary production:
A) oligotrophic;
B) dystrophic
C) polysaprobic;
D) eutrophic;
E) mesotrophic; +
222. Pedobionts that make up most of the biomass of soil fauna:
A) springtails;
B) nematodes;
D) earthworms; +
E) insect larvae
223. Biocenoses on agricultural lands:
A) agrocenosis; +
B) agrosten
C) agrophytocenosis;
D) agrobiogeocenosis
E) agroecosystem.
224. All relationships in the biocenosis are carried out at the level of:
B) communities
C) individuals;
D) families, packs, colonies
E) populations. +
225. The most important factor in the transition from tropical rainforests to semi-evergreen tropical forests is:
A) decrease in temperature
B) seasonal rhythm of precipitation +
C) decrease in precipitation amount
D) decrease in air humidity
E) decrease in solar radiation
226. The appearance of seasonal rhythms in life processes in all animal species during the transition from tropical rain forests to semi-evergreen tropical forests is due to:
A) decrease in temperature
B) decrease in solar radiation
C) a decrease in precipitation
D) decreasing air humidity
E) seasonal rhythm of precipitation +
227. Communities characterized by the presence of a closed grass cover with a varying proportion of shrubs and trees, the seasonality of which is associated with the frequency of precipitation:
A) prairies;
B) semi-evergreen forests;
C) mangroves;
D) savannas; +
E) forest-steppe
228. Large phytophages from the orders of artiodactyls, equids and proboscis are the most widespread and most characteristic group of mammals in ecosystems:
A) prairies;
B) semi-evergreen forests;
C) mangroves;
D) savannas; +
E) forest-steppe
229. The largest accumulations of large phytophages, the biomass of which reaches the maximum values for modern ecosystems of up to 50 kg per 1 ha, are found:
A) on the prairies;
B) in semi-evergreen forests;
C) in savannas; +
D) in the Asian steppes
E) in the forest-steppe
230. Forest communities of the littoral zone of the tropical zone, characterized among animal organisms by a mixture of terrestrial and marine forms, adapted to long-term or temporary life on land:
A) gallery forests;
B) semi-evergreen forests;
C) mangroves; +
D) floodplain forests;
E) tropical rainforests
231. Types of biogeocenoses localized in temperate, subtropical and tropical zones, the appearance, structure, dynamics and productivity of which are controlled by the sharp predominance of evaporation over precipitation:
A) prairies;
B) deserts; +
D) savannas;
E) forest-steppe
232. Life forms of plants in which the mass of roots significantly exceeds the mass of shoots are characteristic of ecosystems:
A) prairies;
B) tundra;
C) steppes;
D) savannas;
E) deserts. +
233. Adaptations, expressed in the presence of a period of rest (hibernation) in seasons unfavorable for active life, development of underground layers, migrations, specific physiological processes, are characteristic of animals living in ecosystems:
B) tundra;
C) deserts; +
D) savannas;
E) forest-steppe
234. The following ecosystems are characterized by the lowest primary production and biomass reserves:
B) tundra;
C) deserts; +
D) savannas;
E) forest-steppe
235. Hydrothermal regime with a discrepancy between warm and wet periods in time (wet, cool winter and dry, hot summer) is the most striking feature of ecosystems:
B) deciduous forests;
C) deserts;
D) savannas;
E) subtropical hard-leaved forests +
236. Forest communities in areas with large amounts of evenly distributed precipitation, moderate temperatures and pronounced seasonal changes:
A) boreal coniferous forests;
B) deciduous forests; +
C) semi-evergreen forests;;
E) forest-steppe
237. An ecosystem in which the seasonality of the development cycles of plants and animals is determined not by temperature, but by rain:
A) broad-leaved forests;
C) deserts;
D) savannas; +
C) subtropical hard-leaved forests
238. Forest communities with the most pronounced vertical structure, consisting of four tiers - tree, shrub, grass (or grass-shrub) and moss (moss-lichen):
A) boreal coniferous forests;
B) deciduous forests; +
C) semi-evergreen forests;;
D) subtropical hard-leaved forests;
E) gallery forests;
Abstract on the topic:
"Biological diversity"
INTRODUCTION
According to the definition given by the World Wildlife Fund (1989), biological diversity is “the entire diversity of life forms on earth, the millions of species of plants, animals, microorganisms with their sets of genes and the complex ecosystems that make up living nature.” Thus, biological diversity should be considered at three levels. Biological diversity at the species level covers the entire range of species on Earth from bacteria and protozoa to the kingdom of multicellular plants, animals and fungi. At a finer scale, biological diversity includes the genetic diversity of species generated both by geographically distant populations and by individuals within the same population. Biological diversity also includes the diversity of biological communities, species, ecosystems formed by communities and the interactions between these levels.
For the continued survival of species and natural communities, all levels of biological diversity are necessary, and all of them are important for humans. Species diversity demonstrates the richness of evolutionary and ecological adaptations of species to different environments. Species diversity serves as a source of diverse natural resources for humans. For example, tropical rainforests, with their rich array of species, produce a remarkable variety of plant and animal products that can be used for food, construction and medicine. Genetic diversity is necessary for any species to maintain reproductive viability, resistance to disease, and the ability to adapt to changing conditions. The genetic diversity of domesticated animals and cultivated plants is especially valuable to those working on breeding programs to maintain and improve modern agricultural species.
Community-level diversity represents the collective response of species to different environmental conditions. Biological communities found in deserts, steppes, forests, and floodplains maintain the continuity of normal ecosystem functioning by providing “maintenance,” such as flood control, soil erosion control, and air and water filtration.
The purpose of the course work is to identify the main biomes of the world and protect their biodiversity.
To achieve the goal, the following tasks were set:
1. Definition of the concept of tundra and forest-tundra;
2. Consideration of the concept of deciduous forests of the boreal zone;
3.Analysis of the steppe ecosystems of the world, deserts of the world;
4.Definition of subtropical deciduous forests;
5. Consideration of the principles of biodiversity protection.
TUNDRA AND FOREST-TUNDRA
The main feature of the tundra is the treelessness of monotonous swampy lowlands in a harsh climate, high relative humidity, strong winds and permafrost. Plants in the tundra are pressed to the surface of the soil, forming densely intertwined shoots in the form of a pillow. A wide variety of life forms can be seen in plant communities.
There is a moss-lichen tundra, where green and other mosses alternate with lichens (the most important of them is moss, which reindeer feed on); shrub tundra, where thickets are widespread, especially dwarf birch (polar willow, bushy alder), and in the Far East - dwarf cedar. Tundra landscapes are not without diversity. Large spaces are occupied by hummocky and hilly tundra (where turf forms hummocks and mounds among swamps), as well as polygonal tundra (with special forms of microrelief in the form of large polygons broken by frost cracks).
In addition to sparse moss-lichen vegetation, perennial cold-resistant grasses (sedge, cotton grass, dryad, buttercups, dandelions, poppies, etc.) are widespread in the tundra. The sight of the tundra blooming in spring makes an indelible impression with its variety of colors and shades, caressing the eye to the very horizon.
Pretty poor animal world The tundra formed during the glaciation period, which determines its relative youth and the presence of endemics, as well as species associated with the sea (birds living in bird colonies; polar bears, pinniped rookeries). Tundra animals have adapted to harsh living conditions. Many of them leave the tundra for the winter; some (for example, lemmings) stay awake under the snow, others hibernate. Arctic fox, ermine, and weasel are widespread; there is a wolf and a fox; of rodents - voles. The endemics of the tundra include: among ungulates - the musk ox and the long-domesticated reindeer; among birds - the white goose, snow bunting, and peregrine falcon. The white and tundra partridges and the horned lark are numerous. The predominant fish species are salmon. Mosquitoes and other blood-sucking insects are abundant.
Tundra areas are found in forest-tundra.
The issue of the boundaries of tundra forests has long been debated. There is no consensus of opinion about either their northern or southern borders. It is not possible to clearly separate forests and tundra, forest-tundra and taiga due to the laws of vegetation continuity. On satellite images and topographic maps built on the basis of aerial photographs of different scales, these boundaries “float”. Forest areas in islands and islets, strips and ribbons of different widths along river valleys often extend far into the tundra. The situation is complicated by the high swampiness of the areas. Although swamps are objects of an azonal nature, when establishing the relationship between the main components of the landscape, they must also be taken into account along with forest and tundra ecosystems. It is quite obvious that the protective strip allocated by the Government Decree cannot reflect the natural boundaries of the tundra forest strip. It is known that this band was established by expert topographic maps and aerial photography materials. It represents only a special economic part of the general forest fund. In order to reduce the number of unproductive areas from a utilitarian point of view, but requiring protection, the forest fund included only territories with a clear predominance of forest formations - ecosystems of the forest type itself.
When identifying the boundaries of this strip, it is necessary, in my opinion, to use a landscape-biological approach. The main plant formations in the territories under consideration are forest, tundra and swamp. In the zone of contact between forest formations and tundra, each type of ecosystem accounts for a total of 33% of the area. But since swamp ecosystems are azonal formations, they can be considered in the landscape, although an integral, but still a secondary element. They can only complement the properties of the main components of ecosystems: either forest or tundra. That is, if one of these main types of vegetation is more than 33 (for the strength of positions - more than 35%), then the formation corresponding to it should be considered decisive. Based on this, from a biological and ecological point of view, the boundary between the tundra and the strip of near-tundra forests should be drawn along the boundaries separating territories covered by forest communities by 35 percent or more. In practice, the northern border of the tundra forest strip, formalized in this way, is proposed to be established using satellite images or topographic maps at a scale of 1:1000000. Of course, when carrying it out, simplifications and generalizations cannot be avoided. Apparently, in this case, the “tundra forest” zone will significantly expand to the north compared to the existing one. This will mean an expansion of the Federal Forest Service's holdings.
When discussing the issue of the northern border of tundra forests, one cannot fail to note the proposals of the famous specialist V.G. Chertovsky. include all spaces of the geobotanical forest-tundra zone, where forest groups are represented in any way today, to this territory. If we consider that the northern limits of forest distribution change over time, it is possible that someday we will return to this point of view.
No less debatable remains the question of the southern boundaries of the tundra forest subzone, i.e. about its border with the northern taiga subzone. This boundary is also very arbitrary, and does not coincide with the boundaries of temperate and cold climate zones, or the natural boundaries of landscapes. If we consider it as the boundary of natural complexes, then the indicators of productivity and sustainability of ecosystems should be put at the forefront. The main indicator, as we see it, should be the criterion of their guaranteed self-renewal. Given the complete uncertainty of this concept in silvicultural practice, we propose to operate with the concept of “sustainable frequency of seed production.” We are talking about edificatory breeds.
Thus, forest-tundra-closed boreal coniferous forests at the northern limit of their distribution usually gradually but steadily become more resistant to forests. Treeless areas appear; to the north there are more and more of them. Low, often ugly trees are separated from each other by 10 m or more.
Between them grow shrubs, dwarf birches, low willows and other plants. Finally, only isolated islands of forest remain, but even those are preserved mainly in places protected from the wind, mainly in river valleys. This border strip between forest and tundra is the forest-tundra, which in many places extends in the form of a relatively narrow zone, but often in some places its diameter (from north to south) reaches hundreds of kilometers. Forest-tundra is a typical transition zone between forest and tundra, and it is often very difficult, if not impossible, to draw a clear boundary between the two zones.
Dark coniferous forests
Dark coniferous forests - the tree stand of which is represented by species with dark evergreen needles - numerous species of spruce, fir and Siberian pine (cedar). Due to the great darkness, the undergrowth in dark coniferous forests is almost undeveloped; the ground cover is dominated by hard-leaved evergreen shrubs and ferns. The soils are usually podzolic. Dark coniferous forests are part of the taiga zone (taiga) of North America and Eurasia, and also form a high-altitude zone in many mountains of the temperate and subtropical geographical zones; they do not enter the Subarctic, just as they are almost absent in the extracontinental longitudinal zone.
Eurasian taiga
The natural taiga zone is located in the north of Eurasia and North America. On the North American continent it stretches from west to east for more than 5 thousand km, and in Eurasia, starting on the Scandinavian Peninsula, it spread to the shores of the Pacific Ocean. The Eurasian taiga is the largest continuous forest zone on Earth. It occupies more than 60% of the territory of the Russian Federation. The taiga contains huge reserves of wood and supplies large amounts of oxygen to the atmosphere. In the north, the taiga smoothly turns into forest-tundra, gradually taiga forests are replaced by open forests, and then by separate groups of trees. The furthest taiga forests enter the forest-tundra are along river valleys, which are most protected from strong northern winds. In the south, the taiga also smoothly transitions into coniferous-deciduous and broad-leaved forests. In these areas, humans have interfered with the natural landscapes for many centuries, so now they represent a complex natural-anthropogenic complex.
The climate of the taiga zone within the temperate climate zone varies from marine in the west of Eurasia to sharply continental in the east. In the west there are relatively warm summers (+10 °C) and mild winters (-10 °C), more precipitation falls than can evaporate. Under conditions of excessive moisture, decomposition products of organic and minerals are carried into the lower soil layers, forming a clarified podzolic horizon, from which the predominant soils of the taiga zone are called podzolic. Permafrost contributes to the stagnation of moisture, so significant areas within this natural zone are occupied by lakes, swamps and swampy woodlands. Dark coniferous forests growing on podzolic and frozen-taiga soils are dominated by spruce and pine and, as a rule, there is no undergrowth. Twilight reigns under the closing crowns; mosses, lichens, herbs, dense ferns and berry bushes- lingonberries, blueberries, blueberries. In the north-west of the European part of Russia, pine forests predominate, and on the western slope of the Urals, which is characterized by large clouds, sufficient precipitation and heavy snow cover, spruce-fir and spruce-fir-cedar forests.
On the eastern slope of the Urals, humidity is less than on the western slope, and therefore the composition of forest vegetation here is different: light coniferous forests predominate - mainly pine, in places with an admixture of larch and cedar (Siberian pine).
The Asian part of the taiga is characterized by light coniferous forests. In the Siberian taiga, summer temperatures in a continental climate rise to +20 °C, and in winter in northeastern Siberia they can drop to -50 °C. On the territory of the West Siberian Lowland, predominantly larch and spruce forests grow in the northern part, pine forests in the central part, and spruce, cedar and fir in the southern part. Light coniferous forests are less demanding on soil and climatic conditions and can grow even on infertile soils. The crowns of these forests are not closed, and through them the sun's rays freely penetrate into the lower tier. The shrub layer of the light-coniferous taiga consists of alder, dwarf birches and willows, and berry bushes.
In Central and North-Eastern Siberia, in conditions of harsh climate and permafrost, larch taiga dominates. Coniferous forests of North America grow in a temperate continental climate with cool summers and excess moisture. The species composition of plants here is richer than in the European and Asian taiga. For centuries, almost the entire taiga zone suffered from negative impact human economic activity: slash-and-burn agriculture, hunting, haymaking in floodplains, selective logging, air pollution, etc. Only in remote areas of Siberia today can one find corners of virgin nature. The balance between natural processes and traditional economic activities, which has developed over thousands of years, is now being destroyed, and the taiga as a natural complex is gradually disappearing.
Coniferous forests of America
There are different opinions about the natural presence of coniferous forests on the plains of temperate latitudes. Particularly in drier regions, the pine forest may present a normal vegetation pattern. This is observed in the warm and dry regions of the southwestern United States, the Iberian Peninsula and the karst areas of the Balkans. Less favorable places on the plain, for example, northern slopes or pits with cold air, can be overgrown exclusively with coniferous species.
Many coniferous forests in relatively densely populated parts of the planet are artificial, since deciduous or mixed forests would be natural there. In Europe and North America they were founded at the end of the 18th century. In Europe, forest restoration was carried out after it had been almost cut down in many areas, and due to the impoverishment of the soil, only persistent conifers were suitable for this. In North America, more valuable hardwood species were cut down at a much greater rate, resulting in coniferous trees becoming the dominant species in the forests. Later, such forests were abandoned, as coniferous trees grew faster and made it possible to make a profit faster. Nowadays, in many places there has been a rethinking of this traditional policy and many forests are gradually being converted into mixed forests.
In many densely populated areas, coniferous forests suffer from exhaust fumes.
The main territory of the remaining 49 states is divided into several regions according to the nature of vegetation. West: This includes the vast Cordillera mountain system. These are the slopes of the Coast Range, Cascade Mountains, Sierra Nevada and Rocky Mountains, covered with coniferous forests. East: the elevated plateaus around the Great Lakes region and the interior forest-steppe plains, as well as the mid-mountain uplands of the Appalachian Mountains, where the main tracts of broadleaf and partially coniferous-broadleaf temperate forests are located. South: subtropical and partly tropical (in southern Florida) forests are common here.
In the west of the country there are the most productive and valuable coniferous forests, which are part of the Pacific Northwest region. Its territory includes the western slopes of the Cascade Mountains in the states of Washington and Oregon and the Coast Range and Sierra Nevada, located in California. Ancient coniferous virgin forests of evergreen sequoia (Sequoia sempervirens), reaching a height of 80-100 m, have been preserved here. The most productive and complex sequoia forests are located in California on the oceanic slopes at an altitude of 900-1000 m above sea level. seas. Along with the sequoia grow no less large Douglas fir (Pseudotsuga manziesii), whose trunks reach 100-115 m in height, and large fir trees: great fir (Abies grandis) with trunks 50-75 m high, noble fir (A. nobilis) - 60-90 m; pretty (A. amabilis) - up to 80 m; Lowa fir (A. lowiana) - up to 80 m; single-color (A. concolor) - 50-60m; Californian, or lovely (A. venusta) - up to 60 m; magnificent (A. magnifica) - up to 70 m. Giant thuja trees (Thuja plicata) 60-75 m high are also found here; Sitka spruce - 80-90 m; Lawson's cypress (Chamaecyparis lawsoniana) - 50-60 m; Californian river cedar, or incense cedar (Calocedrus decurrens) - up to 50 m; western hemlock, etc. Sequoia forests stretch in a strip along the Pacific coast for 640 km and do not go further inland than 50-60 km.
In somewhat drier areas of Southern California and on the western slopes of the Sierra Nevada, areas of once majestic coniferous trees of Sequoiadendron giganteum remain. Most of these areas are included in nature reserves and national parks (Yosemite, Sequoia, Kings Canyon, General Grant, etc.). Companions of the giant sequoiadendron are Lambert pine, or sugar pine (Pinus lambertiana), yellow pine (P. ponderosa), monochromatic and magnificent fir, Californian river cedar, etc. To the south of areas of sequoia forests on the slopes of the Coast Range and Sierra Nevada at an altitude of 1000 to 2500 m in the state of California, pure pine forests of Sabina pine (P. sabiniana) and Lambert pine, reaching a height of 50-60 m, are widespread, to which in some places low (18-20 m) large-cone sugi trees. At an altitude of 2000-2100 m, this species often forms low-growing clear forests.
On the western slopes of the Sierra Nevada (1800-2700 m), Lambert pine forests give way to forests of P. jeffreyi and ponderosa pine. The latter breed is also widespread in areas bordering the Great Plains. There, along the slopes of the Rocky Mountains (1400-2600 m), it forms the famous western pine (ponderosa) forests, constituting 33% of all coniferous forests in the United States. Most of the ponderosa pine forests are part of the Intermountain (Idaho, Nevada, Arizona) and Rocky Mountain (Montana, Wyoming, Colorado, New Mexico) forest growing regions. The following types of pines grow in these areas: mountain pines (P. monticola), Murray pines (P. murrayana), whitestem pines (P. albicaulis), lodgepole pines (P. flexilis) and lodgepole pines (P. contorta). Together with them, at an altitude of 1500-3000 m, spruce (Picea pungens) and Engelmann (P. engelmannii) grow, fir - subalpine (Abies lasiocarpa) and Arizona (A. arizonica), larch - western (Larix occidentalis) and Lyell ( L. lyallii), Mertens hemlock (Tsuga mertensiana) and gray hemlock (Pseudotsuga glauca) and gray hemlock (P. caesia).
IN southern regions The Rocky Mountains, in the states of Arizona, New Mexico, as well as in southern California, are widespread communities of evergreen shrubs - chaparral, among which low pines - bristlecone (P. aristata), cedar (P. cembroides), edible - are found on sandy hillocks and along the slopes (P. edulis), Torrey (P. torreyana), four-cone (P. quadrifolia), etc., as well as evergreen oaks - grass-leaved (Quercus agrifolia), bush (Q. dumosa), etc., adenostoma (Adenostoma fasciculatum), buckthorn (Rhamnus crocea), cherry (Prunus ilicifolia), various heathers, sumac. In total, there are more than one hundred species of shrubs in the chaparral.
Northeast of Minnesota, through the northern Great Lakes states and into Maine, the Northern Hardwood Forest Region is defined. It also includes forests along the northern slopes of the Allegan Mountains, the Allegan Mountains and the Appalachian Mountains (the states of New York, Pennsylvania, West Virginia, Kentucky, North Carolina to Tennessee and northern Georgia). In the north of this area there is a boundary between the distribution of Canadian spruce (Picea canadensis) and black spruce (P. mariana), which is replaced along the slopes of the Appalachians by red spruce (P. rubens). Spruce forests occupy the shores of lakes, river valleys, and border swamps and lowlands. Along with the spruce trees grow lodgepole pine (Pinus rigida), thuja (Thuja occidentalis), American larch (Larix americana) and red maples (Acer rubrum) and black maples (A. nigrum). In drained and elevated areas, mixed forests are represented by Weymouth pine (Pinus strobus), balsam fir (Abies balsamea), Canadian hemlock (Tsuga canadensis), white oaks (Q. alba), mountain oaks (Q. montana), velvet oaks (Q. velutina ), northern (Q. borealis), large-fruited (Q. macrocarpa), etc.; maples - sugar (Acer saccharum), silver (A. saccharinum), Pennsylvania (A. pensylvanicum); jagged chestnut (Castanea dentata), large-leaved beech (Fagus grandifolia), American linden (Tilia americana), smooth hazel (Carya glabra), hop hornbeam (Ostrya virginiana), elm (Ulmus americana), yellow birch (Betula lutea), late bird cherry ( Padus serotina) and other deciduous species. On sandy and loamy dry soils there are pure pine forests formed by Banks pine (Pinus banksiana). They often grow together with the soybean (P. resinosa). The dry slopes of the Appalachian Mountains are inhabited by forests of lodgepole pine (P. pungens).
To the south of the Northern region of coniferous-deciduous forests extend the broad-leaved forests of the Central region. It includes forest areas in the south of the states of Minnesota, Wisconsin and Michigan, in the east of Iowa, Missouri, Illinois, Indiana, Ohio, Kentucky, Tennessee, Pennsylvania and Virginia, in the northeast of Oklahoma and Texas, in the north of Arkansas, Mississippi, Alabama, Georgia , and South Carolina. This area was once characterized by an abundance of forests and a variety of tree species, especially hardwoods. The bulk of the forests were destroyed during the period of settlement of the country and plowing of the lands. They are preserved in isolated areas along river valleys, on the Ozark plateau and in the hilly areas bordering the Appalachian Mountains to the south. Numerous types of oaks are found here: chestnut (Quercus prinus), pointed (Q. acuminata), swamp (Q. palustris), Michaux (Q. michauxii), large-fruited, velvety, white, laurel (Q. laurifolia), red (Q. rubra), Maryland (Q. marilandica), crescent (Q. falcata), black (Q. nigra), small (Q. minor), etc. Chestnuts grow: jagged (Castanea dentata), low-growing (C. pumila); several types of caria (hickory): white (Carya alba), smooth (C. glabra), oval (C. ovata), pecan (C. illinoensis), etc., numerous maples, including sugar, silver, red, ash-leaved (Acer negundo), etc.; horse chestnuts: bicolor (Aesculus discolor), small-flowered (A. parviflora), neglected (A. neglecta), eight-stamened (A. octandra). Along the Allegan Mountains in a narrow strip (through the states of Georgia, South and North Carolina, and Virginia) stretches forests of Carolina hemlock (Tsuga caroliniana), along with which there are elms, oaks, maples, and various willows.
In the eastern part of the region, along with beech (Fagus grandifolia), ash (Fraxinus americana), black walnut (Juglans nigra), such wonderful ancient, tertiary species grow as tulip tree (Liriodendron tulipifera), liquidambar styraciflua, magnolia (Magnolia acuminata, etc.), white acacia (Robonia pseudoacacia) and black locust (R. viscosa).
In the southeast of the country, the Southern Subtropical Pine Forest Region is distinguished, including eastern Texas, southern Oklahoma and Arkansas, Louisiana, Mississippi, Alabama, Georgia and Florida, eastern South and North Carolina, Virginia, Maryland, Delaware and New Jersey. Here, along the coasts of the Gulf of Mexico and the Atlantic, there are significant areas of pine forests (more than 50% of the area of all coniferous forests in the country). Particularly common are subtropical pine forests of incense pine (Pinus taeda), hedgehog pine, or short-coniferous pine (P. echinata), swamp, or long-coniferous pine (P. palustris), late, or lake pine (P. serotina). A smaller area is occupied by forests of Elliott pine, or swamp pine (P. elliottii), sandy pine (P. clausa), and western Indian pine (P. occidentalis). In addition to pines, this area is characterized by Florida yew (Taxus floridana), Virginia juniper (Juniperus virginiana), as well as broad-leaved species: white oak, chestnut oak, laurel oak, Maryland oak, crescent oak, black oak, swamp oak; Florida chestnut (Castanea floridana), large-leaved beech, red and silver maples, etc., black ash, tulip tree, liquidambrus, nyssa sylvestris, magnolias, hickories and other walnut trees.
A small area of tropical forest stands out in southeast Texas and southern Florida. Here among the lowlands and swamps grow swamp cypress (Taxodium distichum), royal (Roystonea regia) and reed (Thrinax spp.) palms, saw palmetto (Serenoa serrulata), Florida yew, cycad (Zamia floridiana), lagooncularia (Laguncularia racemosa), and In places flooded with sea water, mangrove thickets of rhizophora (Rhizophora mangle) are also common.
The Hawaiian Islands are dominated by tropical forests formed by a species of the myrtle family (Eugenia malaccensis), called the “Malayan apple,” white sandalwood (Santalum album), numerous tree ferns, and various vines; A coconut palm is grown on the coast.
Boreal broadleaf forests
Deciduous forests of Europe
Deciduous forests, groups of forest formations in which the tree layer is formed by trees with large or small leaf blades. K L. l. include rain and seasonal evergreen and seasonal deciduous forests of the tropical zone, hard-leaved forests of the subtropical zone and deciduous (summer green) forests of temperate latitudes.
Temperate deciduous forests of the Northern Hemisphere grow in a cool temperate climate, year-round precipitation and a growing season of 4-6 months. Still on Wed. centuries, deciduous forests were distributed in continuous massifs in Europe (from the Iberian Peninsula to Scandinavia); east of the Carpathians, their strip narrowed sharply, wedging out towards the Dnieper, and continued in a narrow intermittent strip beyond the Urals. In the east of North America and East Asia they formed a strip about 2500 km wide from north to south.
Deciduous forests of the temperate zone have long been subject to strong human influence (in their place are the main industrialized countries).
Deciduous forests of the temperate zone, depending on their constituent trees and undergrowth, are characterized by 1-3 tree layers, shrub and herbaceous layers; mosses are common. on stumps and rocks.
The composition of vegetation cover in temperate deciduous forests depends on local climatic conditions. So, in the West. and Center. Beech forests are developed in Europe, and oak and hornbeam forests are found in the east of the Carpathians. From the Urals to Altai L. l. represented by island birch forests - tulips. In the deciduous forests of East Asia, areas of Manchurian-type forests have been preserved, unusually rich in species composition, both in tree and shrub species, and in species of the herbaceous layer; only in the southern part of Kamchatka, on the island. Sakhalin and in some regions of Primorye they are formed by sparse park-type plantings of stone birch. In North America, deciduous forests are represented by formations of beech (in the mountains), beech-magnolia and oak-hickory forests; pl. oak forests are secondary.
Despite their small area, deciduous forests play an important role as regulators of the water regime of the area. They contain many valuable species that are of great practical importance.
Deciduous forests of North America
The soil and litter of deciduous forests are home to many insectivorous invertebrates (ground beetles, rove beetles, millipedes), as well as vertebrates (shrews, moles). In the forests of America, as in East Asia, moles are very diverse. The appearance is original, a star-nosed fish with soft outgrowths at the end of the muzzle in the form of a star made of numerous movable processes. In appearance and lifestyle, the shrew mole from the mountain forests of the Western United States is similar to shrews. Of the shrews, the most widespread, as in Eurasia, are shrews. The pygmy shrew, typical of Canadian maple and ash forests, is more original.
Of the snakes, especially numerous in the south, rattlers and copperheads predominate. Of the former, the most common is the striped, or terrible, rattlesnake, and of the latter, the moccassin snake. In the south, in Florida, the moist areas are dominated by cottonmouths.
The diverse species of American broadleaf forests produce rich crops of beech, linden, maple, ash, walnut, chestnut and acorn seeds. Therefore, among the animal population there are many consumers of these feeds. In our country, such consumers (and in the Old World in general) primarily include various mice and rats. In America, these rodents are absent, but their place is taken by species of the hamster-like group. Peromiscus are called deer mice, or white-footed mice, and Ochorotomis are called golden mice, although in reality they are not mice, but hamsters. Forest voles feed on both seeds and grass. Of the other rodents, gray voles are common in the zone of deciduous forests, as in the Old World, but they are more characteristic of meadow or field landscapes. The water vole - the muskrat - is now acclimatized in Eurasia because of its valuable skin.
As on other continents, deciduous forests are characterized by deer. In North America, races of the same red deer are common as in Eurasia. The American red deer is called wapiti. Wapiti is most similar to deer and wapiti. The most widespread species is a representative of a special subfamily (endemic to the New World), the white-tailed, or Virginia, deer. It penetrates as far south as Brazil. Deer feed on branches of trees and bushes in winter, and also on grass the rest of the time. Due to its high numbers, white-tailed deer are the most important sport hunting object in the United States. Black-tailed deer live in the mountains of the Pacific Coast. It lives not only in deciduous forests, but also in coniferous and xerophytic thickets of chaparral.
Among the birds of broad-leaved forests, insectivores predominate; during the nesting period, small passerines. The species of oatmeal are diverse; for this reason, American forests are closer to the regions of East Asia. Thrush species are also characteristic. Families typical for Eurasia, such as flycatchers and warblers, are absent. They are replaced, respectively, by Tyranaceae and Arboreal species. Both of these families are widespread throughout both Americas, and are most characteristic of forest habitats. Mockingbirds should also be included here.
Most predators (both animals and birds) that feed on vertebrates are widely distributed across the continent. For deciduous forests, predatory mammals are characterized by such species as the large pecan marten - an enemy of squirrels and porcupines, skunk, and striped raccoon from the raccoon family. Nose beetles also penetrate into the subtropical deciduous forests of the south. The striped raccoon is the only species of the family (and the northernmost) that hibernates during the winter. Ecologically similar to the black bear of Southern and Eastern Eurasia, the American baribal. In addition to the ubiquitous common fox, the gray fox is very typical for the zone. This is an animal that has a somewhat extravagant habit for foxes and the entire canine family of climbing trees and even hunting in the treetops. Externally, the gray fox is similar to the ordinary one, differing in color, short ears and muzzle.
In conclusion of the review of the animal world, one animal should be mentioned, which can hardly be compared with any species of Eurasia. This leading climbing lifestyle (with the help of paws and a prehensile tail) opossum is the only representative of the marsupials that penetrates so far north from South America. The distribution of the opossum generally corresponds to the distribution of deciduous forests of the subtropical and temperate latitudes of the continent. The animal is the size of a rabbit and is active at night. It feeds on a variety of small animals, fruits, mushrooms, and can harm fields and gardens. Opossums are hunted for their meat and pelts. The spiny porcupine from a special, also predominantly South American family of arboreal porcupines also leads an arboreal lifestyle.
In terms of reserves of organic matter, deciduous and coniferous-deciduous forests of temperate and subtropical latitudes correspond to similar groups of other continents. It ranges from 400-500 t/ha. In temperate latitudes, productivity is 100-200 c/ha per year, and in subtropical latitudes - up to 300 c/ha. In valleys and wet deltaic areas, productivity can be even higher (Mississippi Delta and some areas of Florida - 500 c/ha or more dry organic matter per year). In this regard, broad-leaved forests are second only to tropical and equatorial forests. The phytomass of chaparral is much less - about 50 t/ha; productivity - about 100 c/ha per year. This is close to the corresponding figures for other Mediterranean types of biocenoses.
Steppe ecosystems of the world
An ecosystem can be defined as a collection of different species of plants, animals and microbes that interact with each other and with their environment in such a way that the entire collection can persist indefinitely for a long time. This definition is a very condensed description of facts observed in nature
Eurasian steppes
The Eurasian steppe is a term often used to describe the vast steppe ecoregion of Eurasia extending from the western borders of the steppes of Hungary to the eastern borders of the steppes of Mongolia. Most of the Euro-Asian steppes are included in the Central Asia region, and only a small part of it is included in Eastern Europe. The term Asian steppe usually describes the Euro-Asian steppe, excluding the westernmost part, i.e. steppes of western Russia, Ukraine and Hungary.
The steppe zone is one of the main land biomes. Under the influence, first of all, of climatic factors, the zonal features of biomes developed. The steppe zone is characterized by a hot and dry climate for most of the year, and in the spring there is a sufficient amount of moisture, so the steppes are characterized by the presence of a large number of ephemerals and ephemeroids among plant species, and many animals are also confined to a seasonal lifestyle, hibernating in dry conditions. and cold season.
3 steppes are represented in Eurasia by steppes, in North America - by prairies, in South America- the pampas, in New Zealand - the Tussoq communities. These are temperate zone spaces occupied by more or less xerophilic vegetation. From the point of view of the living conditions of the animal population of the steppe, they are characterized by the following features: good review, abundance of plant food, relatively dry summer period, existence summer period rest or, as it is now called, semi-rest. In this respect, steppe communities differ sharply from forest communities. Among the predominant life forms of steppe plants, grasses are distinguished, the stems of which are crowded into turf - turf grasses. In the Southern Hemisphere, such turfs are called tussocks. Tussoks can be very tall and their leaves are less rigid than those of the tufted steppe grasses of the Northern Hemisphere, since the climate of communities close to the steppes of the Southern Hemisphere is milder.
Rhizome grasses that do not form turf, with single stems on creeping underground rhizomes, are more widespread in the northern steppes, in contrast to turf grasses, the role of which in the Northern Hemisphere increases to the south.
Thus, the steppe biogeographic zone is characterized by the originality of representatives of the flora and fauna adapted for life in this zone.
Prairies
Prairie (French prairie) is a North American form of steppe, a growing season in the Midwest of the USA and Canada. Makes up the eastern edge of the Great Plains. Limited vegetation, expressed in the rarity of trees and bushes, is due to the inland location and the Rocky Mountains, which shield the prairie from precipitation from the west. Dry climatic conditions are associated with this circumstance.
There are significant areas of steppes in America. They are especially widespread in North America, where they occupy the entire central region of the continent. Here they are called prairies. The vegetation of individual areas of the prairie varies. The American true prairies are most similar to our steppes; their vegetation consists of feather grass, bearded vulture, and keleria, but these plants, close to ours, are represented there by other species. When the cereal and dicotyledonous plants of true prairies reach full development, the height of the grass stand exceeds half a meter. There is no summer break in plant life here.
Grassland prairie occurs in wetter areas where forest can grow along with grassy vegetation. Oak forests occupy the slopes of shallow valleys; flat and elevated areas of meadow prairie are covered with grass consisting of tall grasses. The height of the grass here is about a meter. In the last century, the height of the grass in some places reached the back of a horse.
Most of the North American steppes are occupied by low-grass prairies. This type of herbaceous vegetation is characteristic of the driest areas of the steppes. The grassland of the low-grass prairie is dominated by two grasses - buffalo grass and Gram grass. Their leaves and stems form a thick brush on the soil surface, and their roots form an equally dense plexus in the soil. It is almost impossible for any other plant to penetrate into these dense thickets, so the low-grass steppes are monotonous. The grass in the low-grass steppe reaches a height of 5-7 cm and forms very little plant mass.
American researchers have proven last years that the low-grass steppes originated from true and even grassland prairies.
At the end of the last and beginning of the 20th century, industrial pastoralists kept so many cattle on the prairies that all the natural grasses that were well eaten by animals were completely destroyed and could not be restored. Low-growing grasses and rough dicotyledonous plants survived and spread in the steppe. They formed the low-grain prairies.
Most of the North American prairies are plowed and used for planting a variety of crops.
In South America, an area covered with grassy vegetation is called a pampa. The Pampa is an immense, gently hilly expanse that occupies most of Argentina and Uruguay and reaches in the west to the foot of the Cordillera. In the pampa, several plant groups change over the summer: early grasses give way to late ones, early-flowering dicotyledons give way to late-flowering ones. There are many grasses in the pampa grass, and among the dicotyledons there are especially many species of Compositae. The development of vegetation in the pampa begins in October and ends in March - after all, the pampa is located in the southern hemisphere.
Pampas
Pampa (Pampas) (Spanish: Pampa) is a steppe in the southeast of South America, mainly in the subtropical zone, near the mouth of the Rio Plata. In the west, the pampas are limited by the Andes, in the east by the Atlantic Ocean. To the north lies the Gran Chaco savanna.
Pampa is a herbaceous grassy vegetation on fertile reddish-black soils formed on volcanic rocks. It consists of South American species of those genera of cereals that are widespread in Europe in the temperate steppes (feather grass, bearded grass, fescue). The pampa is connected with the forests of the Brazilian Highlands by a transitional type of vegetation, close to the forest-steppe, where grasses are combined with thickets of evergreen shrubs. The vegetation of the pampa has undergone the most severe destruction and is now almost completely replaced by crops of wheat and other cultivated plants. When the grass cover dies, fertile gray-brown soils are formed. In the open expanses of the steppe, fast-running animals predominate - Pampas deer, Pampas cat, and among birds - the rhea ostrich. Lots of rodents (nutria, viscacha), as well as armadillos.
The Pampa becomes increasingly arid as it moves away from the Atlantic Ocean. The climate of Pampa is moderate. In the east, temperature differences between summer and winter are less significant; in the west, the climate is more continental.
The countries whose territory the pampa affects are Argentina, Uruguay and Brazil. The Pampa is Argentina's main agricultural region and is used primarily for cattle ranching.
Savannah
Savannas (otherwise known as campos or llanos) are steppe-like places characteristic of more elevated tropical countries with a dry continental climate. Unlike true steppes (as well as North American prairies), savannas, in addition to grasses, also contain shrubs and trees, sometimes growing as a whole forest, as, for example, in the so-called “campos cerrados” of Brazil. The herbaceous vegetation of savannas consists mainly of tall (up to ⅓-1 meter) dry and tough-skinned grasses, usually growing in turf; mixed with the cereals are turfs of other perennial grasses and subshrubs, and in damp places flooded in spring, also various representatives of the sedge family (Cyperaceae). Shrubs grow in savannas, sometimes in large thickets, occupying an area of many square meters. Savannah trees are usually short-growing; the tallest of them are no taller than ours fruit trees, which they are very similar to with their crooked stems and branches. Trees and shrubs are sometimes entwined with vines and overgrown with epiphytes. There are few bulbous, tuberous and fleshy plants in savannas, especially in South America. Lichens, mosses and algae are found extremely rarely in savannas, only on stones and trees.
The general appearance of savannas is different, which depends, on the one hand, on the height of the vegetation cover, and on the other hand, on the relative amount of grasses, other perennial grasses, subshrubs, shrubs and trees; for example, the Brazilian savanas (“campos cerrados”) represent actually light, sparse forests, where you can freely walk and drive in any direction; the soil in such forests is covered with herbaceous (and semi-shrub) plant cover of ½ and even 1 meter in height. In savannas of other countries, trees do not grow at all or are extremely rare and are very stunted. The grass cover is also sometimes very low, even pressed to the ground. A special form of savannah is made up of the so-called llanos of Venezuela, where trees are either completely absent or found in limited numbers, with the exception of damp places where palm trees (Mauritia flexuosa, Corypha inermis) and other plants form entire forests (however, these forests do not belong to savannas); in the llanos there are sometimes single specimens of Rhopala (trees from the family Proteaceae) and other trees; sometimes the grains in them form a cover as tall as a person; Between the cereals grow Compositae, legumes, Lamiaceae, etc. During the rainy season, many llanos are flooded by floods of the Orinoco River.
Living conditions in the savannah are very harsh. The soil contains few nutrients; during dry seasons it dries out, and during wet seasons it becomes swampy. In addition, fires often occur there at the end of dry seasons. Plants that have adapted to savannah conditions are very cruel. Thousands of different herbs grow there. But trees, in order to survive, need some specific qualities to protect them from drought and fire. For example, the baobab tree is distinguished by a thick, fire-protected trunk that, like a sponge, can store water reserves. Its long roots absorb moisture deep underground. Acacia has a wide, flat crown that creates shade for the leaves growing below, thereby protecting them from drying out. Many areas of the savannah are now used for ranching and wild life there has completely disappeared. However, in the African savannah there are huge national parks where wild animals still live.
Savannas are characteristic of South America itself, but in other countries one can point out many places that are very similar in the nature of their vegetation to savannas. Such, for example, are the so-called Campine in the Congo (in Africa); in South Africa, some places are covered with vegetation consisting mainly of grasses (Danthonia, Panicum, Eragrostis), other perennial grasses, shrubs and trees (Acacia horrida), so that such places resemble both the prairies of North America and the savannas of South America; similar places are found in Angola. ("Campos Cerrado")
In areas located a few degrees north and south of the equator, the climate is usually very dry. However, during certain months it gets very hot and rainy. Such places, located throughout the world, are called savannah zones. This name comes from the African savanna, which is the largest region with this type of climate. The savannah zones are located between the two tropics - lines where twice a year the sun at noon is exactly at its zenith. At such times, it becomes much hotter there and this causes much more sea water to evaporate, which leads to heavy rains. In the savannah regions closest to the equator, the sun is exactly at its zenith at intermediate times of the year (March and September), so that one rainy season is separated by several months. In the savannah areas furthest from the equator, both rainy seasons are so close in time to each other that they practically merge into one. The duration of the rainy period is from eight to nine months, and at the equatorial borders - from two to three.
The vegetation of savannas is adapted to the dry continental climate and to periodic droughts, which occur in many savannas for entire months. Cereals and other herbs rarely form creeping shoots, but usually grow in tussocks. The leaves of cereals are narrow, dry, hard, hairy or covered with a waxy coating. In cereals and sedges, young leaves remain rolled into a tube. Tree leaves are small, hairy, shiny (“varnished”) or covered with a waxy coating. The vegetation of savannas has a pronounced xerophytic character. Many species contain large amounts of essential oils, especially species from the Verbenaceae, Lamiaceae and Myrtle families of South America. The growth of some perennial herbs, semi-shrubs (and shrubs) is especially peculiar, namely in that the main part of them, located in the ground (probably the stem and roots), grows strongly into an irregular tuberous woody body, from which then numerous, mostly unbranched or weakly branched, offspring. During the dry season, savannah vegetation freezes; savannas turn yellow, and dried out plants are often exposed to fires, due to which the tree bark is usually scorched. With the onset of rains, the savannas come to life, becoming covered with fresh greenery and speckled with numerous different flowers. The eucalyptus forests of Australia are quite similar to the "campos cerratos" of the Brazilians; they are also light and so sparse (the trees are far apart from one another and their crowns do not meet) that it is easy to walk in them and even drive in any direction; the soil in such forests in the rainy season is covered with green thickets, consisting mainly of cereals; During the dry season, the soil is exposed.
Savannah animals were forced to adapt to survive in drought conditions. Large herbivores such as giraffes, zebras, wildebeest, elephants and rhinoceroses are able to travel great distances and, if a place becomes too dry, they go to where it rains and where there is plenty of vegetation. Predators such as lions, cheetahs and hyenas prey on wandering herds of animals. It is difficult for small animals to go in search of water, so they prefer to hibernate throughout the dry season.
Deserts of the world
Sandy deserts
Depending on the rocks that make up the territory, there are: clayey, rocky and sandy deserts. Contrary to the popular idea of deserts as vast expanses of endless undulating rows of sand dunes, only one-fifth of the world's desert area is covered with sand. However, there are also many impressive sand seas there. In the Sahara, sandy deserts, ergs, cover many tens of thousands of square kilometers. The sand that washes there from neighboring highlands is formed as a result of weathering of desert rocks. It is constantly carried by the wind from place to place and eventually accumulates in lowlands and depressions.
Transverse dunes are long ridges of sand located at right angles to the direction of the prevailing wind in the area. The dunes have a horseshoe shape, with their “horns” directed towards the wind. Star dunes often reach enormous sizes. They are formed under the influence of winds blowing from different directions. Created by very strong winds, they often stretch for many kilometers and reach 100 m in height. The windswept hollows between rows of spear-shaped dunes with exposed bedrock have traditionally served as major trade routes for nomadic desert peoples.
The dunes have an almost regular crescent shape, and their pointed tails - horns - are extended in the direction of the wind. They are found mainly in deserts where there is relatively little sand, so the dunes move along gravel-strewn surfaces or even exposed bedrock. Of all the dunes, dunes are the most mobile.
There are also star-shaped dunes that resemble entire mountains of sand. Sometimes their height reaches 300 m, and from above such dunes look like a starfish with curved tentacle rays. They form where winds alternately blow from different directions, and, as a rule, do not move anywhere.
The climate and topography of sandy deserts significantly complicate the conditions for road construction and operation. The relief of sandy deserts is unstable. The higher the wind speed at the earth's surface, the larger particles it moves.
The flow of wind-sandy flow around uneven sandy relief is accompanied by the formation of areas of local increase in flow speeds, eddies, and calm zones. In the turbulence zone, sand is dispersed, and in the calm zone it is deposited.
The movement of sand grains in the direction of the wind causes a general movement of the surface layers of sand in the form of ripples. I gradually climb the slopes of sandy hills; grains of sand, after being transported over the top, roll down and are deposited in a calm zone on the leeward side. As a result, the sand hills gradually move in the direction of the wind. Such sands are called mobile sands. The speed of movement of sand mounds decreases with increasing their height.
The following characteristic forms of relief of sandy deserts formed under the influence of wind are distinguished: barchans, dune chains, sand ridges, hilly sands. The formation of each relief form is associated with certain conditions for the movement of sands, with the strength and direction of the prevailing winds.
Dunes are sand hills that are single or located in groups, up to 3-5 m high or more, up to 100 m wide, having a lunar crescent shape in plan with horns oriented in the direction of the wind. The windward gentle slope, depending on the sand size, has a steepness of 1:3-1:5, the leeward slope is 1:1.5-1:2. This form of relief is the most unstable and easily susceptible to wind. Single dunes are formed on the outskirts of loose sands, on smooth, bare and flat takyr and solonchaks
Takyrs are flat surfaces covered with hard clay soil. Takyrs are located mainly along the edge of the sands and represent the dry bottom of temporary lakes formed during the rapid melting of snow or after heavy rains. Clay and silt particles settling from water over time form a dense waterproof layer. After rains, the takyrs are covered with water for several days, and then, when the water evaporates, the clay cracks into individual tiles.
Rocky deserts
Rocky deserts come in several types, depending on the type of surface. It can be formed by stone, crushed stone, pebbles, and gypsum. The surface of some deserts is highly permeable to water, while others create a dense, waterproof crust. In the first case, the water goes to a depth inaccessible to plant roots. In the second, it evaporates from the surface, further cementing the desert crust.
Where there used to be water, salts form. In some places their concentration is so high that they create a crust on the surface. There are places whose thickness is 15 cm with hummocks up to a meter high. If the moisture has not completely evaporated, salt marshes have the appearance of a marshy swamp.
Some of the most common types of deserts are stony, gravelly, rubble-pebble and gypsum deserts. They are united by roughness, hardness and surface density. The water permeability of rocky soils varies. The largest pebbly and crushed stone fragments, lying quite loosely, easily allow water to pass through, and precipitation quickly seeps to great depths inaccessible to plants. More often, however, surfaces are common where pebbles or crushed stone are cemented with sand or clay particles. In such deserts, rocky debris lies densely, forming the so-called desert pavement.
The relief of rocky deserts varies. Among them there are areas of smooth and flat plateaus, slightly sloping or flat plains, slopes, gentle hills and ridges. Gullies and gullies form on the slopes. There are frequent temperature changes and moisture condensation at night.
Life in rocky deserts is particularly dependent on rainfall and evaporation. In the most severe conditions it is simply impossible. The rocky deserts of the Sahara (hamads), occupying up to 70% of its area, are often devoid of higher vegetation. Cushion-shaped freodolia and limonastrum bushes are established only on isolated rocky screes. In wetter deserts Central Asia although sparsely, but evenly covered with wormwood and solyanka. Low-growing saxaul thickets are common on the sandy-pebble plains of Central Asia.
In tropical deserts, succulents settle on rocky surfaces. In South Africa these are cissus with thick barrel-shaped trunks, milkweed, “tree lily”; in the tropical part of America - a variety of cacti, yuccas and agaves. In rocky deserts there are many different lichens that cover stones and color them white, black, blood red or lemon yellow.
Scorpions, phalanges, and geckos live under the stones. The copperhead is found here more often than in other places.
Subtropical deciduous forests
Tropical and subtropical deciduous biomes do not respond to seasonal changes temperatures, but on the amount of precipitation that falls during the season. During the dry season, plants shed their leaves to conserve moisture and avoid death from desiccation. Leaf fall in such forests does not depend on the season, at different latitudes of different hemispheres, even within a small region, forests can differ in the time and duration of leaf fall, different slopes of the same mountain or vegetation on river banks and watersheds can be like a patchwork quilt of bare and leafy trees.
Subtropical evergreen forests
Subtropical evergreen forest - a forest common in subtropical zones.
Dense broad-leaved forest with evergreen tree and shrub species.
The subtropical climate of the Mediterranean is dry, precipitation in the form of rain falls in winter, even mild frosts are extremely rare, summers are dry and hot. The subtropical forests of the Mediterranean are dominated by thickets of evergreen shrubs and low trees. Trees stand sparsely, and various herbs and shrubs grow wildly between them. Junipers grow here, noble laurel, strawberry tree, which annually sheds its bark, wild olives, delicate myrtle, roses. These types of forests are characteristic mainly in the Mediterranean, and in the mountains of the tropics and subtropics.
The subtropics on the eastern edges of the continents are characterized by a more humid climate. Atmospheric precipitation falls unevenly, but there is more rain in the summer, that is, at a time when vegetation especially needs moisture. Dense humid forests of evergreen oaks, magnolias, and camphor laurel predominate here. Numerous lianas, thickets of tall bamboos and various shrubs enhance the uniqueness of the humid subtropical forest.
Subtropical forest differs from humid tropical forests in lower species diversity, a decrease in the number of epiphytes and lianas, as well as the appearance of coniferous and tree ferns in the forest stand.
The subtropical zone is characterized by a wide variety of climatic conditions, expressed in the peculiarities of moisture in the western, inland and eastern sectors. The western sector of the continent has a Mediterranean type of climate, the uniqueness of which lies in the discrepancy between the wet and warm periods. The average annual precipitation on the plains is 300-400 mm (in the mountains up to 3000 mm), the majority of which falls in winter. Winter is warm, the average temperature in January is not lower than 4 C. Summer is hot and dry, the average temperature in July is above 19 C. Under these conditions, Mediterranean hard-leaved plant communities have formed on brown soils. In the mountains, brown soils give way to brown forest soils.
The main area of distribution of hard-leaved forests and shrubs in the subtropical zone of Eurasia is the Mediterranean territory, developed by ancient civilizations. Grazing by goats and sheep, fires and land exploitation have led to the almost complete destruction of natural vegetation cover and soil erosion. Climax communities here were represented by evergreen hard-leaved forests dominated by the oak genus. In the western part of the Mediterranean, with sufficient rainfall on various parent rocks, a common species was sclerophyte holm oak up to 20 m high. The shrub layer included low-growing trees and shrubs: boxwood, strawberry tree, phyllyria, evergreen viburnum, pistachio and many others. The grass and moss cover was sparse. Cork oak forests grew on very poor acidic soils. In eastern Greece and on the Anatolian coast of the Mediterranean Sea, holm oak forests were replaced by kermes oak forests. In warmer parts of the Mediterranean, oak stands were replaced by stands of wild olive (wild olive tree), pistachio lentiscus and ceratonia. The mountainous regions were characterized by forests of European fir, cedar (Lebanon), and black pine. Pines (Italian, Aleppo and maritime) grew on the sandy soils of the plains. As a result of deforestation, various shrub communities have long arisen in the Mediterranean. The first stage of forest degradation is apparently represented by a maquis shrub community with isolated trees resistant to fires and deforestation. Its species composition is formed by a variety of shrubby plants of the undergrowth of degraded oak forests: different kinds Erica, cistus, strawberry tree, myrtle, pistachio, wild olive, carob, etc. Shrubs are often intertwined with climbing, often thorny plants, sarsaparilla, multi-colored blackberry, evergreen rose, etc. An abundance of thorny and climbing plants makes maquis difficult to pass. In place of the reduced maquis, the formation of a garigue community of low-growing shrubs, subshrubs and xerophilic herbaceous plants develops. Low-growing (up to 1.5 m) thickets of kermes oak dominate, which are not eaten by livestock and quickly occupy new territories after fires and logging. The families of Lamiaceae, legumes and Rosaceae, which produce essential oils, are abundantly represented in garigi. Typical plants include pistachio, juniper, lavender, sage, thyme, rosemary, cistus, etc. Gariga has various local names, for example, in Spain, tomillaria. The next formation formed on the site of the degraded maquis is freegan, the vegetation cover of which is extremely sparse. Often these are rocky wastelands. Gradually, all plants eaten by livestock disappear from the vegetation cover; for this reason, geophytes (asphodelus), poisonous (euphorbia) and prickly (astragalus, Asteraceae) plants predominate in the composition of freegana. In the lower zone of the Mediterranean mountains, including western Transcaucasia, subtropical evergreen laurel, or laurel-leaved, forests, named after the predominant species of various types of laurel, are common.
Tropical rain forests
Evergreen tropical rain forests are located along the equator, in an area where precipitation is 2000-2500 mm/g with a fairly even distribution between months. Rainforests are located in three main areas: 1) the largest continuous tract in the Amazon and Orinoco basins in South America; 2) in the basins of the Congo, Niger and Zambezi rivers in Africa and on the island of Madagascar; 3) Indo-Malayan and Borneo islands - New Guinea(Fig. 7.3). The annual variation of temperatures in these areas is quite even and in some cases reduces seasonal rhythms in general or smoothes them out.
In tropical rainforests, trees form three layers: 1) rare tall trees create an upper layer above the general canopy level; 2) a canopy forming a continuous evergreen cover at a height of 25-35 m; 3) the lower tier, which clearly appears as a dense forest only in places where there is a gap in the canopy. Herbaceous vegetation and shrubs are practically absent. But there are a large number of vines and epiphytes. The species diversity of plants is very high - on several hectares you can find as many species as are not found in the flora of all of Europe (Yu. Odum, 1986). The number of tree species varies according to different accounts, but apparently reaches 170 or more, although there are no more than 20 species of grass. The number of species of interlayer plants (vines, epiphytes, etc.) together with herbs number 200-300 or more.
Tropical rainforests are quite ancient climax ecosystems in which the cycle of nutrients is brought to perfection - they are little lost and immediately enter the biological cycle carried out by mutualistic organisms and shallow, mostly aerial, with powerful mycorrhiza, tree roots. It is thanks to this that forests grow so luxuriantly on poor soils.
No less diverse than the flora and fauna of these forests. Most animals, including mammals, exist in the upper layers of vegetation. The diversity of animal species can be illustrated by the following figures: in 15 km2 of rain forest in Panama there are 20,000 species of insects, while in the same area in western Europe there are only a few hundred.
Of the large animals of the tropical forests, we will name only a few of the most famous: monkeys, jaguars, anteaters, sloths, pumas, apes, buffalo, Indian elephant, peacock, parrots, condor, king vulture and many others.
Typical for tropical forests high speed evolution and speciation. Many species became part of more northern communities. Therefore, it is very important to preserve these forests as a “gene resource”.
Tropical rainforests have large biomass and the highest productivity of terrestrial biocenoses.
For a forest to recover to its climax state, a long successional cycle is required. To speed up the process, it is proposed, for example, to cut it down in narrow clearings, leaving plants that are of no value to industry, without disturbing the supply of nutrients in the root cushions, and then seeding from unaffected areas will help quickly restore the forest to its original appearance.
BIODIVERSITY LEVELS
Biodiversity levels
Diversity can be considered as the most important parameter of biosystems, associated with their vital characteristics, which are criteria for efficiency and are extremized during their development (stability, entropy production, etc.). The extreme (maximum or minimum) value of the efficiency criterion of the biosystem G* (Fig. 1) is achieved at the optimal level of diversity D*. In other words, the biosystem achieves its goal at an optimal level of diversity. A decrease or increase in diversity compared to its optimal value leads to a decrease in the efficiency, stability or other vital characteristics of the biosystem.
Critical or permissible levels diversity is determined by the same relationship between the criterion of system efficiency and its diversity. Obviously, there are values of the efficiency criterion at which the system ceases to exist, for example, the minimum values of stability or energy efficiency of the Go system. These critical values correspond to the levels of system diversity (Do), which are the maximum permissible, or critical, levels.
The possibility of the existence of optimal diversity values in biosystems at the population and biocenotic levels is shown on empirical data and the results of biodiversity modeling. The idea of critical levels of diversity is today one of the theoretical principles of wildlife conservation (the concept of minimum population size, critical levels of genetic diversity in populations, minimum area of ecosystems, etc.).
Passive and active methods of protecting biodiversity
To regulate the impact of any type of anthropogenic activity on biodiversity, only a few methods are used:
Impact assessment on environment(EIA) is a method of identifying serious problems before they manifest themselves. The most important step in such an assessment is the area survey. For example, in easily vulnerable island ecosystems, all tourist accommodation and services facilities should be located at a sufficient distance from the most vulnerable areas and well above the level of maximum tide, since many beaches are characterized by natural processes of erosion and sediment deposition.
A proposed strategy analysis (SEA) is designed to examine a proposed strategy, plan, or program and evaluate its impact and the environmental consequences of implementation.
Carrying Capacity Assessment (CCA) is the determination of the maximum load from human activities or the maximum number of environmental users that a natural or man-made resource or system can support without seriously threatening it.
Environmental impact assessment is a strategically important legal tool for the protection of biodiversity, as it aims to eliminate problems before the implementation of projects. Such an assessment should be carried out within the framework of individual industries, types of land use, programs and plans: in particular, when planning the construction of highways, changes in the water regime of a river basin, forest management, etc. If the project has already become part of an approved plan or program, it is often too late or impossible to make such an assessment at the implementation stage to prevent major damage.
As a result of the transformation of nature by man, many species of animals and plants have been brought to the brink of destruction. Measures to protect such species have become an urgent need. Red Books are compiled, the extraction of rare species is prohibited, international trade is strictly limited, nature reserves, national parks, and other specially protected natural areas are created. Unfortunately, some species of animals are pushed to such a brink that these generally accepted, traditional conservation measures are no longer enough for them. To save them, it is necessary to take more active actions, as they say - to use intensive methods of protection. Quite a lot of such methods are known. They can be aimed both at creating optimal conditions for reproduction, and at optimizing the food supply or protective conditions of the habitat. The creation of devices to prevent the death of animals on power lines or during agricultural work, captive breeding and the resettlement of rare species are all various methods of intensive wildlife conservation, which foreign literature received such a name as managing wild animal populations. In our country, the term “biotechnical measures” is more often used. For quite a long time, biotechnical measures were mainly widespread that had purely utilitarian goals - increasing the number of valuable commercial species. At the same time, feeding, constructing artificial nests, and other assistance to animals were undertaken by humans for other, disinterested reasons, including for environmental purposes. The most ancient traditions have various types of biotechnical work aimed at protecting birds
CONCLUSION
Biodiversity has been defined as “the variability of living organisms from all sources, including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within a species, diversity of species and diversity of ecosystems." This definition became the official definition from the point of view of the letter of the law, since it was included in the UN Convention on Biodiversity, which was adopted by all countries of the Earth, with the exception of Andorra, Brunei, the Vatican, Iraq, Somalia and the USA. The UN established the International Day for Biological Diversity. It is quite difficult to determine the need for the conservation and maintenance of biodiversity in any objective way, since it depends on the point of view of the person assessing this need. However, there are three main reasons to conserve biodiversity: From a utilitarian point of view, the elements of biodiversity are resources that are of real benefit to humans today or may be useful in the future. Biodiversity itself provides both economic and scientific benefits (for example, in the search for new drugs or treatments). Choosing to conserve biodiversity is an ethical choice. Humanity as a whole is part of the planet’s ecological system, and therefore it must take care of the biosphere (in essence, we all depend on its well-being). The significance of biodiversity can also be characterized in aesthetic, essential and ethical terms. Nature is celebrated and celebrated by artists, poets and musicians all over the world; For humans, nature is an eternal and enduring value.
Tundra (from Finnish tunturi - treeless bare hill), a type of biome with characteristic treelessness in the subarctic zone of the Northern Hemisphere. It occupies an area of about 3 million km2, stretching along the northern coast of North America and Eurasia in a continuous strip up to 500 km wide. Tundra is also found on some islands near Antarctica. In the mountains it forms a high-altitude landscape belt (mountain tundra).
Forest-tundra - closed boreal coniferous forests at the northern limit of their distribution usually gradually but steadily become more resistant to forests. Treeless areas appear; to the north there are more and more of them. Low, often ugly trees are separated from each other by 10 m or more.
Dark coniferous forests - the tree stand of which is represented by species with dark evergreen needles - numerous species of spruce, fir and Siberian pine (cedar).
Coniferous forest is a forest consisting almost exclusively of coniferous trees. A significant part of coniferous forests is located in the cold climate of northern latitudes as taiga, but coniferous forests are also found in other parts of the planet. In Central Europe, many mountain ranges are covered with them.
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