Ecology__Questions and answers level “C”
Why can the number of commercial fish decline sharply when predatory fish are destroyed in a reservoir?
1) the destruction of predators leads to a sharp increase in the number of herbivorous fish and increased competition between them;
2) a large number of herbivorous fish contributes to a decrease in the food supply, the spread of various diseases among them, this will lead to mass death of fish.
What changes in the meadow ecosystem could a decrease in the number of pollinating insects lead to?
1) reduction in the number of insect-pollinated plants, changes in the species composition of plants;
2) reduction in the number and change in the species composition of herbivorous animals; 3) reduction in the number of insectivorous animals.
Based on the rule of the ecological pyramid, determine how much grain is needed for the forest to grow one eagle owl weighing 3.5 kg, if the food chain looks like:
cereal grain - mouse vole - ferret - eagle owl.
1) according to the rule of the ecological pyramid, the biomass of each subsequent trophic level decreases
approximately 10 times;
2) therefore, to feed an eagle owl you need 35 kg of ferret biomass (if the mass of one ferret is about 0.5 kg, then this is -
70 ferrets, 350 kg of vole mouse biomass is needed to feed the ferrets (if a vole mouse weighs about
100 g, then this is 35,000 voles), which need 3,500 kg of grain for nutrition.
Why is acid rain dangerous?
First of all, heavy metal oxides that fall into the soil with rain are toxic. Groundwater penetrates water bodies and poisons them. In turn, this threatens the death of the population of water bodies. Toxic substances also affect the composition of the soil and the root systems of plants, and this leads to inhibition of their vital activity and death.
How does the structure of a mixed forest biocenosis differ from the structure of a birch grove?
1) Number of species;
2) the number of tiers;
3) species composition, diversity of species.
How natural ecosystem different from an agroecosystem?
1. Greater biodiversity and diversity of food links and chains.
2. Balanced circulation of substances.
3. The participation of solar energy in the cycle of substances and long periods of existence.
What is the difference between biogeocenosis and ecosystem?
An ecosystem has arbitrary boundaries (from a drop of water with microorganisms to the biosphere), while the boundaries of a biogeocenosis are determined by the nature of the vegetation cover. The concept of ecosystem is used both to describe simple parts of a biogeocenosis (a rotting stump in a forest) and to describe artificial complexes (an aquarium). Biogeocenosis is a purely terrestrial formation that has clear boundaries.
Ecosystem and biogeocenosis are similar concepts, but not identical. Any biogeocenosis is an ecosystem. For example, a forest is an ecosystem, but when we specify the type of forest - spruce forest, blueberry forest - it is a biogeocenosis.
Why do populations sometimes experience an explosion in the number of individuals, and then a sharp drop?
This happens for a number of reasons. For example, when there is an excess of food and a small number of predators, the population size increases. And due to the increase in the number of individuals, the amount of food decreases, the number of predators increases + a lot of animals look for new habitats in search of food, while some individuals die. All of the above leads to a decrease in the number of individuals.
What is an obligatory link in the agrocenosis food chain?
Humans are an essential link in the agrocenosis food chain.
Ants live in the stems of some plants. What benefit does the plant have from the ants, and what does the ants benefit from the plant?
Based on the rule of the ecological pyramid, determine how much plankton is needed for one dolphin weighing 300 kg to grow in the sea, if the food chain looks like: plankton - non-predatory fish - predatory fish - dolphin.
Response elements:
1) according to the rule of the ecological pyramid, the biomass of each subsequent trophic level decreases approximately 10 times;
2) therefore, to feed a dolphin you need 3 tons of predatory fish, to feed it you need 30 tons of non-predatory fish, which need 300 tons of plankton to feed it.
In America, many birds build nests in thorny thickets of cacti. What is this interaction between living organisms called and what is its biological meaning?
Response elements:
1) such interaction is mutually beneficial and is called symbiosis;
2) thickets of thorny cacti protect bird nests from predators;
3) birds destroy insects, pests of cacti, and fertilize the soil with droppings.
Based on the rule of the ecological pyramid, determine how many cereals are needed for the development of one golden eagle weighing 7 kg, if the food chain looks like: cereals - grasshoppers - frogs - snakes - golden eagle.
Response elements:
2) according to the rule of the ecological pyramid, the biomass of each subsequent trophic level decreases
approximately 10 times;
2) therefore, to feed a golden eagle you need 70 kg of snakes (if the mass of one snake is 200 g, then this is 350 snakes), to feed these snakes you need 700 kg of frogs (if the mass of a frog is 100 g, then this is 7000 frogs), to feed these frogs you need 7 tons of grasshoppers, and to feed these grasshoppers you need 70 tons of cereal plants.
Fishermen know that rivers and streams developed by beavers contain more fish than reservoirs without beavers. Explain this fact?
Response elements:
1) beavers build dams that prevent small aquatic animals that serve as food from drifting downstream
2) standing and shallow water in ponds dammed by beavers warms up well, which contributes to the creation
conditions for spawning river fish and favorable development of fry.
What are the mechanisms of action of anthropogenic factors on biocenoses?
Response elements:
impact on biocenoses as a result of urban development, agriculture, deforestation, etc., which leads to changes in the ranges of species and disruption of their population structure;
environmental pollution, which can inhibit the vital activity of individual species and their communities, cause the death of organisms and stimulate the mutation process;
extermination of certain species (for example, valuable from a commercial or hunting point of view).
There are significantly fewer herbaceous plants in a spruce forest than in a birch grove. Explain this phenomenon.
Response elements:
1) in a grove, much more light passes through the tree crowns than in a spruce forest; light is a limiting factor for many plants;
2) only shade-tolerant herbaceous plants can exist in a spruce forest.
What are the properties of biogeocenosis?
Biogeocenosis is an open, self-regulating system that is stable and capable of metabolism and energy. Biocenosis is part of the biosphere. Biogeocenosis consists of abiotic and biotic components. It is characterized by biomass, population density, its components, and diversity of species. The living components of biogeocenosis are producers (plants), consumers (animals), and decomposers (bacteria and fungi).
The food chains of natural biogeocenoses include different functional groups: producers, consumers, decomposers. Explain what role organisms of these groups play in the cycle of substances and energy conversion.
Response elements:
1) Producers - organisms that produce organic substances from inorganic ones, are the first link in the food chain and ecological pyramid. In organic substances resulting from the processes of photo- or chemosynthesis, energy accumulation occurs.
2) Consumers - organisms that consume ready-made organic substances created by producers, but do not decompose organic substances into mineral components. They use the energy of organic substances for their life processes.
3) Decomposers are organisms that, in the course of their life, convert organic residues into inorganic substances, which are included in the cycle of substances in nature. The decomposers use the energy released in this process for their vital processes.
What is the basis for the stability of ecosystems?
Response elements:
1) diversity of species of plants, animals and other organisms
2) branched food chains (networks), the presence of several trophic levels
3) balanced circulation of substances
What determines the sustainability of natural ecosystems?
Response elements:
1) species diversity
2) the number of links in the power chain
3) self-regulation and self-renewal
4) closed cycle of substances
What are called population waves?
Fluctuations in the number of individuals in a population
The population of perch in the river is declining as a result of water pollution from sewage, a decrease in the number of herbivorous fish, and a decrease in the oxygen content in the water in winter. What groups of environmental factors are presented in this list?
1) Anthropogenic.
2) Biotic.
3) Abiotic.
To combat insect pests, people use chemicals. Indicate at least 3 changes in the life of the oak forest if all herbivorous insects are destroyed by chemical means. Explain why these changes will occur.
Response elements:
1) the number of insect-pollinated plants will sharply decrease, since herbivorous insects are plant pollinators;
2) the number of insectivorous organisms (consumers of the second order) will sharply decrease or disappear due to a violation power circuits;
3) part chemical substances, which were used to destroy insects, will get into the soil, which will lead to disruption of plant life, death of soil flora and fauna, all violations can lead to the death of the oak forest.
In some forest biocenoses, to protect chicken birds, mass shooting of daytime birds was carried out. birds of prey. Explain how this event affected the number of chickens.
Elements of the answer: 1) at first the number of chickens increased, since their enemies were destroyed (naturally regulating the number); 2) then the number of chickens decreased due to lack of food; 3) the number of sick and weakened individuals increased due to the spread of diseases and the lack of predators, as a result of which their numbers decreased.
What is the ecological significance of nodule bacteria for plants?
Nodule bacteria form a symbiosis with leguminous plants and participate in the fixation of atmospheric nitrogen into mineral compounds available to plants.
What is the name of an environmental factor whose quantitative significance exceeds the endurance of a species, and thereby limits the spread of the species even if all other factors are favorable?
Limiting factor/limiting factor.
What are the connections between organisms called when one species uses excretory products, dead remains, or even living individuals of another species for its structures?
Factory connections.
What are the differences between land-air and aquatic habitats?
Response elements:
1) density;
3) amplitude of temperature fluctuations;
4) illumination.
What mechanisms exist to slow down the growth of populations as their density increases?
Response elements:
1) the frequency of contacts between individuals increases, which causes a stressful state in them, reducing the birth rate and increasing mortality;
2) emigration to new habitats, regional zones, where conditions are less favorable and mortality increases, is increasing;
3) changes occur in the genetic composition of the population, for example, rapidly reproducing individuals are replaced by slowly reproducing ones.
What are the main differences between agrocenoses and natural new biocenoses?
Response elements:
1) insignificant species diversity;
2) incomplete circulation of substances;
3) the source of energy is not only the Sun, but also human activity;
4) lack of self-regulation.
Explain how self-healing of a part of a spruce forest that has burned out as a result of a forest fire will occur.
Response elements:
1) herbaceous, light-loving plants develop first;
2) then birch, aspen, and pine shoots appear, the seeds of which fell with the help of the wind, and a small-leaved or pine forest is formed;
3) under the canopy of light-loving species, shade-tolerant spruce trees develop, which will subsequently completely displace other trees.
Explain the advantages of biological pest control methods over chemical ones.
Pollution of the environment is prevented, while fauna and flora are preserved.
What is the basis for the formation of diverse food chains in ecosystems?
Response elements:
1) diversity of species, the presence of producers, consumers, decomposers among them;
2) feeding species with a variety of foods (broad food specialization).
Why is the relationship between pike and perch considered competitive in a river ecosystem?
Response elements:
1) are predators, feed on similar food;
2) live in the same body of water, need similar living conditions, and mutually oppress each other.
Why can the number of commercial herbivorous fish sharply decrease when predatory fish are destroyed in a reservoir?
Response elements:
1) the destruction of predators leads to a sharp increase in the number of herbivorous fish and increased competition between them;
2) a large number of herbivorous fish contributes to a decrease in the food supply, the spread of various diseases among them, this will lead to mass death
Make a food chain and identify the second-order consumer using all the named representatives: hawk, apple flowers, great tit, apple flower beetle.
Response elements:
1) apple flowers - apple beetle - great tit - hawk
2) second-order consumer - great tit
Why is oxygen concentration currently decreasing in the lower atmosphere?
Response elements:
1) reduction of the Earth’s green cover as a result of deforestation and death of phytoplankton in the World Ocean due to its pollution;
2) oxygen consumption by vehicles and industry.
What are the features of the biosphere as the shell of the Earth?
Response elements:
1) biogeochemical processes take place in the biosphere, the geological activity of all organisms is manifested;
2) continuous biogenic cycle of substances, regulated by the activities of organisms;
3) the biosphere converts the energy of the Sun into the energy of organic substances.
IN AND. Vernadsky wrote: "On earth's surface there is no chemical force more constantly active, and therefore more powerful in its final consequences, than living organisms taken as a whole." Explain what changes have occurred in the lithosphere due to the vital activity of living organisms.
Response elements:
1) soil formation;
2) the formation of a number of minerals: hard and brown coal, peat, limestone, etc.;
3) destruction of rocks.
Why does humid smog appear in urban environments?
The reasons for the appearance of humid smog in cities are the high content of pollutants, dust, smoke and humid, windless weather in the air.
Why is it necessary to maintain biodiversity to preserve the biosphere?
Response elements:
1)biodiversity is the basis of various chains and food networks in the ecosystems of the biosphere;
2) the diversity of food chains and networks is the basis for a balanced circulation of substances and the preservation of the integrity of the biosphere;
3) a balanced circulation of substances is the basis for stability, self-regulation and preservation of the biosphere.
What organisms make up plankton?
There are three accumulations of biomass in the World Ocean: mineral, benthos and plankton. Plankton is formed in upper layers water heated and illuminated by the sun. Plankton is very diverse. These are unicellular, as well as primitive multicellular plants and animals, united common property: Their body density is equal to the density of water. Thanks to this, planktonic organisms do not sink or float; they are suspended in the water, as if floating in it (the literal translation of this term is “floating”).
Let us formulate the answer: “Plankton inhabits the upper layer of water to a depth of 100 m and is represented by organisms suspended in water. There are phytoplankton (unicellular and filamentous algae) and zooplankton (protozoa, copepods).”
Why are power chains never long and usually consist of 4-5 links?
During the transfer of matter and energy, a significant portion of the energy is lost (see background material). Therefore, each new link in the food chain receives less and less energy. A complete loss of energy stops the food chain. The reason is the lack of energy, which is lost in every link of the food chain.
How are the concepts of biotope and biocenosis related?
Biocenosis is a set of populations of different species existing together in nature. Biotope (habitat) is a territory occupied in nature by a biocenosis. Uniting with the biotope, the biocenosis creates a unified system of living and non-living components - biogeocenosis. Any biocenosis is combined with its biotope into an integral system - biogeocenosis.
What is the significance for living organisms of changing daylight hours?
Changing the length of the day (photoperiod) for most plants and animals is the main factor in the regulation of seasonal cycles. The response of organisms to changes in day length is called photoperiodism. Thus, a decrease in the length of the day determines the onset of winter dormancy in plants and cold-blooded animals, the desire to migrate in birds, molting in mammals, etc. The lengthening spring day stimulates sap flow in trees and shrubs, the development of shoots from the buds, and the manifestation of nesting instincts in birds etc. Photoperiod serves as an accurate astronomical predictor of seasonal changes in temperature and other conditions.
What is the cause of the greenhouse effect?
The greenhouse effect is the process of gradual warming on our planet as a result of an increase in the concentration in the atmosphere of anthropogenic impurities (carbon dioxide, methane, nitrogen oxide, ozone, freons), which, while passing through Sun rays, prevent long-wave thermal radiation from the earth's surface. Some of this absorbed thermal radiation is reflected by the atmosphere, returns back to the earth's surface and heats the surface layer of air, creating the greenhouse effect. The main source of anthropogenic carbon dioxide is the combustion of coal, oil, gas and other fuels.
What consequences can result from adding excess mineral fertilizers to the soil?
To environmental pollution.
To combat insect pests, people use chemicals. Indicate at least 3 changes in the life of the oak grove if it chemically all herbivorous insects will be destroyed. Explain why they will happen.
Response elements:
1) the number of insect-pollinated plants will sharply decrease, since herbivorous insects are plant pollinators;
2) the number of insectivorous organisms (consumers of the second order) will sharply decrease or disappear due to disruption of food chains;
3) some of the chemicals used to kill insects will get into the soil, which will lead to disruption of plant life, death of soil flora and fauna, all violations can lead to the death of the oak forest.
What are the biochemical functions of living matter?
Biochemical functions of living matter:
1. Energy function - accumulation of solar energy by plants (or chemical energy by some bacteria) and its transmission through food chains. Green plants form 99% of the planet's primary production (about 150-200 billion tons of dry organic matter per year).
2. Gas - the release and absorption of oxygen, carbon dioxide, methane, hydrogen sulfide during photosynthesis, respiration, and vital processes.
3. Concentration function - the increase and accumulation of certain chemical elements (nitrogen, phosphorus, silicon, calcium, magnesium) by concentrating organisms in their veins. As a result of this activity, accumulations of limestone, peat, coal, etc. occurred.
4. The redox function is the oxidation of substances containing atoms with a variable oxidation state. For example, the oxidation of carbohydrates to carbon dioxide and its reduction to carbohydrates.
5. The destructive function is the mineralization of organic remains into mineral compounds, which are involved in the biological cycle.
What is the merit of the scientific ideas of V.I. Vernadsky?
The meaning of the teachings of V.I. Vernadsky's idea of the biosphere is that he showed the role of living organisms in the geochemical evolution of planet Earth. This idea made it possible to understand the role of the biosphere in the fate of each individual person and humanity as a whole. Since the biosphere is a global ecological system, and humans are part of this system, human activity in the biosphere can be both beneficial and detrimental to its existence.
What is the participation of functional groups of organisms in the biosphere cycle of substances?
Response elements:
1) producers synthesize organic substances from inorganic substances (carbon dioxide, water, nitrogen, phosphorus and other minerals), release oxygen;
2) all functional groups of organisms use and transform organic substances, oxidize them during respiration, absorbing oxygen and releasing
carbon dioxide and water;
3) decomposers decompose organic substances into inorganic compounds of nitrogen, phosphorus, etc., returning them to the environment.
What organisms in the ecosystem contribute to decomposition? organic waste management?
Organic waste refers to dead organic matter. Destructors (decomposers) mineralize (decompose) dead organic matter.
Answer: Decomposers are bacteria, lower fungi, and some worms.
Why the relationship between moose and bison in ecology Is the mixed forest system considered competition?
The key concept that determines the formulation of the answer is “competition.”
Competition is an antagonistic relationship between organisms (in this case, between different species) that use the same resources (food, territory, light, etc.)
Moose and bison are herbivores.
Answer: They eat the same plant foods.
What regulates seasonal phenomena in the life of an org nisms?
Plays an important role in regulating the activity of living organisms and their development. duration of light exposure- fotoperiod. A change in the length of daylight hours is, as it were, a trigger mechanism that sequentially includes physiological processes leading to growth and flowering of plants in the spring, fruiting in the summer and shedding of leaves in the fall, as well as molting and accumulation of fat, migration and reproduction in birds and mammals, and the onset of dormancy in insects
Answer: Changing the length of the day (photoperiodism).
Mass extermination of wolves in a number of regions during led to a decrease in the number of ungulates, for example measures of deer. How can this be explained?
Answer: Wolves play the role of orderlies, destroy sick and weak animals, carrying out the role of natural selection. The disappearance of wolves leads to the spread of diseases among ungulates and a decrease in their numbers.
Why in the terrestrial food chain from link to link, Does biomass usually decrease?
To answer, you must use the rule of the ecological pyramid and the definition of “biomass”.
Answer: Life processes in each link of the food chain consume energy contained in organic substances, part of it (80-90%) is dissipated in space in the form of heat.
What are the reasons for the change in biogeocenoses?
Answer:
reasons for changing biogeocenoses: changing of the climate, human activities, natural phenomena, as well as changes in the habitat of species living in them;
displacement of old species by more competitive species;
an increase in species diversity, food chains, and the establishment of a closed cycle of substances are the reasons for the emergence of a more stable biogeocenosis.
Explain how self-regulation occurs in reservoir using the example of population ratio pike and roach .
Self-regulation in ecosystems is based on food connections. In this example, the pike is a predator that consumes roach as food.
Answer:
1) with an increase in the number of roaches, the number of pikes increases;
2) an increase in the number of pikes leads to a decrease in the number of roaches;
3) in this way self-regulation of fish in the reservoir is carried out
What is the difference ground-air environment from the waters Noah?
In your answer it is necessary to highlight the properties characteristic roofing feltco For ground-air environment.
Answer:
differences in temperature fluctuations (wide amplitude of fluctuations in the ground-air environment);
degree of illumination (more than in water);
density (less dense than water).
Clover grows in meadows and is pollinated by bumblebees. What biotic factors can lead to reduction in the clover population?
Biotic factors are factors of living nature. Answer:
1) reduction in the number of bumblebees;
increase in the number of herbivores;
reproduction of competing plants (cereals, etc.).
Why are moose considered primary consumers?
Answer:
feed on plants, consuming their organic matter;
use the energy contained in organic substances;
serve as food for predatory animals.
Goals and objectives of the lesson:
Formation of knowledge among students:
- about biocenosis as a sustainable system;
- about natural and artificial biocenoses;
- about the obligatory components of the biocenosis:
- producers;
- consumers;
- decomposers.
- Introducing students to the reasons for the stability of natural biocenosis and the instability of artificial ones.
Lesson type. Discussion lecture using presentation.
Equipment. Computers, projector, CD "Biology", electronic tests.
During the classes:
I. Updating knowledge.
Individual survey:
1. What is the evidence that natural selection is the leading cause of animal evolution?
2. Why is the emergence of habitats in nature and their types the result of the adaptation of animals?
3. What are the patterns of distribution of animals in nature?
II. Learning new material.
Children, looking at the topic of the lesson, formulate the goals and objectives of the lesson.
! (suggested answer):
- find out what biocenosis is;
- What does artificial and natural biocenosis mean?
Word to the teacher:
We are all concerned about a serious question:
What is biocenosis?
I will solve this problem, friends, -
This is such a big family:
Animals and birds, beetles, spiders,
Forest, there are birches, aspens, oaks,
Worms and mice, air, earth,
Fallen leaves, maybe pine needles,
Even the path where you carried mushrooms,
This is what biocenosis is.
What do you think, based on the poem you read, what definition can be given to the concept of “biocenosis”?
Biocenosis is a community (totality) of plants, animals and other organisms.
There are 2 types (types) of biocenosis: natural and artificial (see slide 3). Try to determine what is the difference between these biocenoses. Give examples.
A natural biocenosis is one that nature created. For example, a lake, a forest.
An artificial biocenosis is one created by man. For example, a garden, a vegetable garden.
Natural biocenoses.
The composition of the inhabitants in each of them is not accidental; it depends on the conditions of the given territory and is adapted to them. Biocenoses can be rich in species and poor, for example: in the tundra, poor species composition, and in tropical forests – rich (see slides 4-7)
The higher the number of species, the more resistant the biocenosis is to various interventions.
The stability of biocenoses is also determined by their tiering - spatial and temporal (see slide 8).
What do you think these concepts mean?
Tiers - floors.
Spatial – located in space (triple dimension).
Temporal – located in time (changes over time)
Spatial layering (see slide 9) is characteristic of both animals and plants. Each tier is inhabited by individuals of its own species, but this does not prevent various animals from being in other tiers. However, the main stages of animal life take place in certain tiers. For example, bird nests are located in some tiers, and the search for food can occur in others.
If producers are organisms that produce a substance, then who are consumers?
! Consumers are those organisms that consume a substance.
Herbivorous animals that create organic substances, but of animal origin, are called consumers of the first order (see slide 13).
So, we found out who the producers and consumers are. Think and tell me, who are decomposers and what role should they play?
! Decomposers are organisms that process the remains of dead animals and plants.
Decomposers are organisms that feed on the remains of dead plants and animals (see slide 14). These include bacteria, fungi and some animals, such as worms.
In a natural biocenosis, self-regulation of the number of individuals of each group occurs.
What features do you think the artificial biocenosis will have?
! Only what man has planted will grow there, and only a few species of animals will live.
Agriculture led to the destruction of natural and creation of artificial biocenoses (agrobiocenoses). Growing large areas of plants of the same species, for example, potatoes, wheat, led to a sharp reduction in connections between species. The agrobiocenosis is characterized by insignificant stability, because there is no tiering (both temporal and spatial).
Cultivated plants form a specific composition of the inhabitants of the animal world with a predominance of herbivorous species, mainly insect pests. All individuals are characterized by good adaptability to rapid changes in vegetation cover and omnivory.
To combat them, people use various methods, use pesticides, polluting the environment, destroying both harmful and beneficial animals. To maintain the sustainability of artificial biocenoses, large financial costs are required.
For example, consider the biocenosis of a reservoir (see slide 16) .
Producers here are all types of plants, which in most cases are located in the upper layers. Microscopic algae form phytoplankton.
First order consumers are microscopic animals that form zooplankton, which feed on phytoplankton and directly depend on its development.
Second order consumers are fish that feed on crustaceans and insects.
Second order consumers are predatory fish.
Consumers can live at various depths, including at the bottom.
The remains of the vital activity of all organisms sink to the bottom and become food for decomposers, which decompose them into inorganic substances.
III. Physical exercise.
One two three four.
Biofamilies were studied
Learned a lot of new things
And a little tired.
We turn our eyes
Let's shake our heads.
Hands, legs pulled,
Take a good breath,
They leaned over once and twice.
Are you feeling dizzy?
Well, if everything is okay with you,
Let's work in a notebook.
IV. Consolidation of new material.
1. Work in a notebook (consolidating the concepts of “biocenosis”, “natural biocenosis”, “artificial biocenosis”).
RT. Page 132, no. 1, no. 2.
2. Independent work (working on concepts).
Strong students consider the biocenosis of a reservoir (work on sheets - templates).
Weak students watch the film “Ants” and answer questions (work on sheets - templates).
A certain time is given for work. After time has passed, students answer the questions posed (comment on the display of their material).
3. This is interesting.
Sheets (with different information) are distributed to students. After 2–3 minutes, you are asked to read out your 2 favorite facts.
Performing test tasks in the “Knowing” program. Students open the “Knowing” folder on the Desktop, select the “Biocenosis” test and begin testing.
IV. Lesson summary. Reflection. D/z.
Question 1. Prove that spatial and temporal tiers increase the stability of the biocenosis.
Spatial and temporal tiering allows a large number species coexist in the same territory, as it ensures a wider use of light, heat, moisture and thereby reduces competition. And a community with greater species diversity has a greater ability to adapt to the changing conditions of living and inanimate nature, i.e., higher stability.
Question 2. Give examples known to you that confirm the presence of temporal or spatial tiers in animals.
An example of spatial tiering in animals is the distribution of nesting sites in birds. There are species of birds that nest on the ground (chickens, grouse, buntings, pipits, etc.), in the bush layer (bullfinches, warblers, nightingales, song thrushes, etc.), in the crowns of trees (crests, goldfinches, finches, etc.) .
Temporal layering is illustrated by different calendar dates of nesting. For example, finches hatch chicks in the spring, and crossbills hatch in winter.
Question 3. Why are there consumers of the second and more orders, but no producers of the second order?
Producers are organisms that produce primary organic substances from inorganic ones. For example, plants use the energy of the sun to produce them from carbon dioxide and water. Therefore, there cannot be second order producers. All of them belong to the first trophic level.
Consumers are consumers of organic substances. They can be divided into herbivores and carnivores, i.e., classified as order I and II.
Question 4. Why are cases of mass reproduction of pests observed in natural biocenoses much less often than in artificial ones?
This is explained by the fact that in natural biocenoses the species composition and relationships between species are balanced. The introduction of a foreign species into a stable system of natural biocenosis and its mass reproduction is difficult. In an artificial biocenosis, the laws of interaction between species are directionally violated (to obtain high productivity of one species) and there are no natural barriers to the mass reproduction of pests.
53. Natural and artificial biocenoses
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>> Biocenosis and its stability
§ 15. Biocenosis and its stability
Remember
Communities
tiers
vegetation
Biocenosis is a complex natural system. The entire complex of species living together and connected with each other is called a biocenosis (“bios” - life, “cenos” - community).
Rice. 64. Pond biocinosis
In nature, biocenoses come in different sizes. This is, for example, the biocenosis of a moss hummock, a decaying stump, a meadow, a pond, a swamp, a forest (Fig. 64, 65). There are man-made biocenoses - an aquarium, a terrarium, a greenhouse, a greenhouse. In all cases, we identify a community of organisms in which species living together are adapted to a certain set of abiotic conditions and maintain their existence through connections with each other. Smaller biocenoses in nature are parts of larger ones, as, for example, all the inhabitants of a forest clearing or the trunk of a fallen tree are part of the general forest biocenosis, and coastal and bottom biocenoses are parts of the general river or lake community.
Biocenoses are not random collections of different organisms. In similar natural conditions and with a similar composition of fauna and flora, similar, naturally repeating biocenoses arise. We can confidently assume that in different oak groves in the belt of broad-leaved forests we can also find linden, maple, hazel, among the grasses - pine, wood anemone and other very specific plant species, among animals - squirrel, wild boar, yellow-throated mouse, tit - blue tit, pied flycatcher, jay, acorn weevil. In spruce forests there is a different set of species, and some of them may be common with others communities, and some are found only in spruce forests.
Rice. 65. Biocinosis of oak forest
Thus, all Live nature consists not only of individual organisms and species, but also of various biocenoses into which representatives are grouped various types. Biocenoses, like populations, is the supraorganismal level of life organization.
The total number of species that can coexist in one biocenosis in nature is very large. The richest species are tropical forests. Their diversity has not yet been described sufficiently fully. It is estimated that on an area of one square kilometer in tropical forest There are several hundred thousand species of plants and animals, not counting microorganisms and fungi. But even in those natural communities that form in fairly harsh conditions, for example in the tundra or highlands, thousands of species of organisms live together.
Members of the biocenosis are connected by direct or indirect food relationships, creating Wednesday habitats for each other and mutually limit number. Species have adapted to living together over a long period of evolution. In biocenoses there are processes of struggle for existence and natural selection.
Any biocenosis is a complex natural system that is maintained through connections between species and has a complex internal structure.
Species structure of biocenosis. The species included in the biocenosis are very unequal in number. Some of them are widespread, others are few in number, and others are very rare. The most widespread species of biocenosis are called dominants or dominant species. For example, in a spruce-blueberry forest, spruce constantly dominates among the trees, among terrestrial plants - blueberries, green mosses, among birds - the chiffchaff, titmouse, among chicken birds - hazel grouse, and among mouse-like rodents the bank vole predominates.
Mass species form the main core of the biocenosis. A number of species reach high numbers only periodically, sometimes becoming part of the mass species. In spruce forests these are finches, crossbills, and wood mice. The most diverse species in biocenoses are rare and small in number.
If you construct a graph reflecting the proportion of species with different numbers, then for most biocenoses in the part of the scale where rare species are represented, the curve rises sharply (Fig. 66). This means that in a stable biocenosis rare species many, but very numerous - few.
In a tropical forest, for example, the diversity of trees is so great that in an area of 1 km2 it is sometimes difficult to find several trees of the same species.
What role do mass species play in biocenoses? Dominant species determine the main connections in the community. They create its basic structure and appearance.
Part mass species- important environment-formers that greatly influence the living conditions for others. In spruce forests, the distribution of light and precipitation, the microclimate, the mosaic of soil and biocenose conditions - everything is determined by the spruce. The life of many terrestrial plants and thousands of animal species, from squirrels and tits to numerous small arthropods in the forest floor, depends on the condition of the spruce stand.
Small-numbered species constitute, as it were, a reserve of the community. In the current situation, they cannot realize their reproductive potential, but in changed conditions they are able to join the dominants or even take their place. Among the many small species there will always be those for which deviation of conditions from the average norm will be favorable.
Thus, the biocenosis remains stable and is not destroyed by various weather fluctuations and other external influences, including moderate anthropogenic ones.
The ratio of species by abundance creates species structure biocenosis. For each type of biocenosis it is quite natural.
Distribution of species in space. Biocenoses are also characterized by a regular distribution of species in space. The basis of this distribution is formed by vegetation. Plants create tiers in biocenoses, placing foliage under each other in accordance with their shape growth and love of light. In forests temperate climate there can be up to 5-6 tiers of plants.
Animals also live in separate layers of vegetation, but due to their mobility different types animals can master several tiers at once. Squirrels, for example, build nests and breed squirrels in trees, and can collect nuts, mushrooms, and berries on the ground.
For the species diversity of biocenoses, it is also important whether the vegetation in the territory is uniformly or mosaically distributed. In forests, where there are many clearings and edges, the species composition of plants, birds, and insects is much richer than in vast monochromatic plantings. This phenomenon is called the edge effect and is often used in the creation of parks and other artificial forest plantations where they want to restore species diversity.
Ecological niche of the species. As already discussed, species coexist in the same biocenosis in cases where they diverge in environmental requirements and thereby weaken competition with each other. Thus, each species uses resources in its own way and has its own characteristics of connections with other species.
The position that a species occupies within a biocenosis is called its ecological niche. The ecological niche of a species is characterized by the limits of its endurance in relation to various factors, the nature of its connection with other species, its way of life, and its distribution in space.
The ecological niches of co-living species may partially overlap, but never completely coincide, since in this case the law of competitive exclusion comes into play and one species displaces another from a given biocenosis.
Stability of biocenoses. Changes that occur in biocenoses are related to their stability in different ways. If, for example, one competing species displaces another, significant changes in the biocenosis will not occur, especially if this species is not widespread. The corresponding ecological niche will simply be occupied by another species. For example, the sable, living in the coniferous forests of Siberia, is a polyphagous predator that feeds on small rodents, birds, pine nuts, berries and insects, obtaining its food both on the ground and in trees. The pine marten plays the same role in northern European forests. Therefore, if sables live in the forest instead of martens, the forest biocenosis will retain all its main features.
Small species are the most vulnerable part of the biocenosis. Their populations are often at the limit of survival. Therefore, they are the first to disappear from communities due to anthropogenic influences that worsen the conditions of existence of the biocenosis.
Losses of rare and small species also do not significantly change the basic biocenotic connections until a certain time. So, a spruce forest or oak grove near big city can persist for a long time and even be renewed despite the fact that due to constant visits by people, trampling, collecting fruits and flowers, etc., many species of plants, birds, and insects disappear from them. The composition of such forests becomes poorer, and their stability weakens gradually and imperceptibly. A weakened, depleted forest biocenosis can collapse suddenly, within short term for seemingly insignificant reasons. For example, litter begins to accumulate due to lack or low activity soil inhabitants, trees exhaust reserves of mineral nutrition, weaken, are attacked by massive pests and die.
The loss of the main environment-forming species from the biocenosis leads to the destruction of the entire system and a change in communities. Such changes in nature are often made by humans by cutting down forests, creating overgrazing of livestock in the steppes and meadows, or overfishing in reservoirs.
Sudden destruction of previously stable communities is a feature of all complex systems, whose internal connections are gradually weakening. Knowledge of these patterns is important for creating artificial communities and maintaining natural biocenoses. When restoring steppes, forests, and planting forest parks, they strive to create a complex species and spatial structure of communities, selecting species that complement each other and get along together, and achieve the appearance of a diverse range of small forms to stabilize the emerging community.
Examples and additional information
1. The name “biocenosis” was introduced into science by the German scientist Karl Moebius in 1877. While studying how to increase the productivity of oyster farming on the shallows of the North Sea, he discovered that oysters, together with other species of marine animals, form close communities that are confined to a specific soil, salinity and water temperature. In these communities there is a struggle for existence and regulation of the number of species, so their productivity has limits. This led to a practical conclusion: “If it is desirable to increase the number of animals and plants compared to what is available in natural communities, then eggs and young should be protected from enemies, given the necessary food and sufficient space. This occurs in the artificial cultivation of oysters, in fishing, in forestry, field and garden farming. In them we are dealing with artificial living communities in which the important factor is the work of human thought and the work of hands.”
2. Tiering exists not only in the above-ground, but also in the underground part of the biocenosis. The roots of different plants penetrate to different depths. In this way, plants partially avoid competition by sharing resources. Soil animals also master different underground “floors”. Among earthworms, for example, some dig vertical holes up to a meter deep and drag rotted leaves into them. Others do not penetrate deeper than 20-30 cm, feeding on soil humus. Still others are not found in mineral layers at all, but spend their entire lives in the layer of forest litter, processing it on site.
3. The composition and structure of biocenoses undergo regular cyclical changes associated with the change of seasons. In winter, perennial plants go into a state of deep dormancy, and annuals die, leaving seeds. Cold-blooded animals fall into torpor. Only warm-blooded animals are active - birds and mammals, but some of them also hibernate or migrate south. From spring to autumn, the vegetation cover also changes naturally, showing consistency in the flowering and fruiting of different species, and the activity of animals, and the activity of microorganisms. Superimposed on this regular cyclicity is variability weather conditions in different years. Cold or hot, dry or rainy periods deflect the population dynamics of individual species, disrupting the correct cyclicity. Biocenoses are thus in a state of constant variability. Their stability is based on regulatory relationships that maintain the approximate ratios of the numbers of the main species.
4. In the steppes and deserts among mammals, the following groups of species with a similar lifestyle are possible: 1) permanent underground inhabitants, 2) burrowing species feeding on the surface, 3) jumping herbivores, 4) fast running herbivores, 5) fast running predators. These ecological niches of mammals in the open landscapes of different continents are occupied by different species that have similar life forms. Thus, similar types of biocenoses can arise on a different species basis.
5. To compare biocenoses, different methods are used, for example, calculations using the Jaccard formula:
where A is the number of species of a given group in the first community, B - in the second, and C is the number of species common to both communities.
Biocenoses are compared in pairs, comparing the species composition according to systematic groups, for example, lists of flowering plants, mosses, lichens, birds, mammals, insects, etc. The similarity is expressed as a percentage. So, if in each biocenosis there are 10 species of a given group and 5 of them are found in both one and another community, then the species similarity will be 33%, and if common types 8 is 66%.
Questions.
1. Name the dominant and small species in the bird population: 1) urban areas, 2) rural villages.
2. How do the biocenoses of a natural oak forest and a city park differ in the set of species of plants, birds and mammals?
3. List the groups of organisms from which a stable aquarium biocenosis can be formed.
Tasks.
1. Compare the species composition of nesting birds in three areas of the Volga steppe. Use Jaccard's formula.
Feather grass steppe: steppe lark, skylark, little lark, dancing wheatear, common wheatear, steppe harrier, steppe eagle. Crops with shelterbelts: steppe lark, skylark, little lark, yellow wagtail, pink starling, quail, field harrier. Crops without shelterbelts: steppe lark, skylark, little lark, dancing wheatear, lapwing, field harrier.
In which areas are communities more similar to each other in the composition of breeding birds?
2. Select from the list of mammals below the species that occupy similar ecological niches in the Eurasian and Australian steppes: kangaroo, mole rat, jerboa, marsupial wolf, saiga, marsupial mole, wolf, ground squirrel, hamster, zokor, wombat Which mammals are absent in their lifestyle Australian steppes?
Topics for discussion.
1. Constructing forest belts, parks, gardens, etc. , a person selects only a small number of basic species. In natural biocenoses there are many times more species. Does this mean we can't create sustainable communities?
3. How can the edge effect be used when planning agricultural land?
4. When a species is removed from the biocenosis, the rest take its place, increase its numbers and fulfill its role. Why then care about preserving the species diversity of communities?
5. Are there unstable communities in nature?
All living nature that surrounds us - animals, plants, mushrooms and other living organisms - is a whole biocenosis or part, for example, of a regional biocenosis or the biocenosis of a separate part. All biocenoses have different conditions and may differ in the types of organisms and plants.
In contact with
Biocenosis is community, a set of living organisms in the nature of a certain territorial area. The concept also implies environmental conditions. If a separate territory is taken, then within its boundaries there should be approximately the same climate. The biocenosis can extend to the inhabitants of land, water and.
All organisms in the biocenosis are closely related to each other. There are food connections, or with the habitat and distribution. Some populations use others to build their own shelters.
There is also a vertical and horizontal structure of the biocenosis.
Attention! The biocenosis can be natural or artificial, that is, man-made.
In the 19th century, biology was actively developing, like other branches of science. Scientists continued to describe living organisms. In order to simplify the task of describing groups of organisms that inhabit any certain territory, Karl August Moebius was the first to coin the term "biocenosis". This happened in 1877.
Signs of biocenosis
There are the following signs of biocenosis:
- There is a close relationship between the populations.
- The biotic connection between all components is stable.
- Organisms adapt to each other and in groups.
- A biological cycle is observed in this area.
- Organisms interact with each other, so they are mutually necessary.
Components
The components of a biocenosis are all living organisms. They are divided into three large groups:
- consumers - consumers of finished substances (for example, predators);
- producers - can produce nutrients independently (for example, green plants);
- decomposers are those organisms that are the final link in the food chain, that is, they decompose dead organisms (for example, fungi and bacteria).
Components of biocenosis
Abiotic part of the biocenosis
Abiotic environment- this is climate, weather, relief, landscape, etc., that is, this is the inanimate part. Conditions will differ on different parts of the continents. The harsher the conditions, the fewer species will be present in the area. IN equatorial belt The most favorable climate is warm and humid, so endemic species are most often found in such areas (many of which can be found on the Australian mainland).
A separate area of the abiotic environment called a biotope.
Attention! The richness of species within the biocenosis depends on the conditions and nature of the abiotic environment.
Types of biocenosis
In biology, types of biocenosis are classified according to the following characteristics.
By spatial location:
- Vertical (tiered);
- Horizontal (mosaic).
By origin:
- Natural (natural);
- Artificial (man-made).
By connection type species within the biocenosis:
- Trophic (food chains);
- Factory (arrangement of habitats of an organism with the help of dead organisms);
- Topical (individuals of one species serve as habitats or influence the lives of other species);
- Phoric (participation of some species in the distribution of the habitat of others).
Spatial structure of the biocenosis
Natural biocenosis
Natural biocenosis is characterized by the fact that it has a natural origin. A person does not interfere with the processes occurring in it. For example: Volga River, forest, steppe, meadow, mountains. Unlike artificial ones, natural ones have a larger scale.
If a person interferes with natural environment, then the balance between species is disrupted. Irreversible processes are taking place - the extinction and disappearance of some species of plants and animals, they are indicated in "". Those species that are on the verge of extinction are listed in the Red Book.
Let's look at examples of natural biocenosis.
River
The river is natural biocenosis. It is home to various animals, plants and bacteria. The views will vary depending on the location of the river. If the river is located in the north, then the diversity of the living world will be poor, but if it is closer to the equator, then the abundance and diversity of species living there will be rich.
Inhabitants of river biocenoses: beluga, perch, crucian carp, pike, sterlet, herring, ide, bream, pike perch, ruffe, smelt, burbot, crayfish, asp, carp, carp, catfish, roach, track, silver carp, sabrefish, various freshwater algae and many other living organisms.
Forest
Forest is example of a natural look. The forest biocenosis is rich in trees, shrubs, grass, animals that live in the air, on the ground and in the soil. Here you can find mushrooms. Various bacteria also live in the forest.
Representatives of the forest biocenosis ( animal world): wolf, fox, elk, wild boar, squirrel, hedgehog, hare, bear, elk, tit, woodpecker, chaffinch, cuckoo, oriole, black grouse, wood grouse, thrush, owl, ant, ladybug, pine silkworm, grasshopper, tick and many other animals.
Representatives of the forest biocenosis ( vegetable world): birch, linden, maple, elderberry, corydalis, oak, pine, spruce, aspen, lily of the valley, kupir, strawberry, blackberry, dandelion, snowdrop, violet, forget-me-not, lungwort, hazel and many other plants.
The forest biocenosis is represented by the following mushrooms: boletus, boletus, White mushroom, toadstool, fly agaric, oyster mushroom, puffball, chanterelle, oiler, honey fungus, morel, russula, champignon, saffron milk cap, etc.
Natural and artificial biocenosis
Artificial biocenosis
An artificial biocenosis differs from a natural one in that it created by human hands to satisfy their needs or the needs of the whole society. In such systems, a person himself designs the required conditions. Examples of such systems are: garden, vegetable garden, field, forest plantation, apiary, aquarium, canal, pond, etc.
The emergence of artificial environments led to the destruction of natural biocenoses, the development Agriculture and the agricultural sector of the economy.
Examples of artificial classification
For example, in a field, greenhouse, garden or vegetable garden, a person breeds cultivated plants(vegetables, grain crops, fruit-bearing plants, etc.). So that they don't die, certain conditions are created: Irrigation systems for watering, lighting. The soil is saturated with the missing elements with the help of fertilizers. Plants are treated with chemicals to protect them from being eaten by pests, etc.
Forest belts are planted near fields, on the slopes of ravines, near railways and roads. Near the fields they are needed in order to reduce evaporation and retain snow in the spring, i.e. for control water regime land. Trees also protect seeds from being blown away by the wind and protect the soil from erosion.
Trees are planted on the slopes of ravines in order to prevent and slow down their growth, since the roots will hold the soil.
Trees along roads are necessary to prevent snow, dust, and sand from driving transport routes.
Attention! Man creates artificial biocenoses in order to improve the life of society. But excessive interference with nature is fraught with consequences.
Horizontal structure of biocenosis
The horizontal structure of a biocenosis differs from the tiered one in that the abundance of species living on its territory changes not vertically, but horizontally.
For example, we can consider the most global example. The diversity, abundance and richness of the living world varies by zone. In the Arctic desert zone, in the Arctic climatic zone, the flora and fauna are sparse and poor. As you approach the zone tropical forests, in the tropical climate zone, the number and diversity of species will increase. So we were able to trace changes in the number of species within the biocenosis, and even changes in their structure (since they have to adapt to different climate conditions). This is a natural mosaic.
And artificial mosaicism arises under the influence of man on environment. For example, deforestation, sowing meadows, draining swamps, etc. In a place where people have not changed the conditions, the organisms will remain. And those places where conditions have changed will be inhabited by new populations. The components of the biocenosis will also differ.
Biocenosis
The concept of biogeocenosis and ecosystem
Conclusion
Let's summarize: biocenosis has different classifications depending on its origin, relationships between organisms and location in space. They differ in territorial scale and the species that live within their boundaries. Signs of biocenosis can be classified separately for each area.