Despite the fact that ecosystem and biogeocenosis are used as one and the same concept, ecosystems differ in their size and complexity. While biogeocenoses have definite clear boundaries, it is very difficult to delineate the boundaries of ecosystems. An example of small ecosystems is a drop of water with microbes, a rotting stump with its microorganisms, fungi and small vertebrates. An ecosystem can include several biogeo-cenoses.
Thus, an ecosystem is a broader concept than a biogeocenosis. Any biogeocenosis is an ecosystem, but not every ecosystem can be called a biogeocenosis.
Biosphere
The largest ecosystem is the biosphere.
Life on Earth has not been interrupted for over 3.5 billion years thanks to the circulation of substances in nature. Plants create organic matter from minerals, water, carbon dioxide, using streams of solar energy. Animals use ready-made organic substances in the process of feeding, and fungi and bacteria gradually destroy them to mineral ones. Mineral substances are used again by plants. This is how biological circulation.
In a natural community, living organisms are connected not only with each other, but also with inanimate nature. The close connection between living and nonliving components of nature forms an ecosystem.
The cycle of substances in the ecosystem can occur if there are reserves of nutrients necessary for life and three groups of organisms that form a natural community - producers (producers), consumers (consumers), destroyers (reducers) of organic substances.
There is not a single species on Earth that would not serve as food for others or itself would not feed on organisms of other species. A number of living organisms in the ecosystem, through which the transfer of energy contained in organic substances occurs, is called power circuit.
Herbivorous animals use the energy stored by plants in the form of organic substances. However, most of the energy of the plant is spent on vital processes. Predators feeding on plant-based animals receive less energy. The remains of animals and plants, containing even less energy, are gradually consumed by fungi and bacteria. Thus, due to the constant expenditure of energy on the processes of life-activity, food chains usually consist of a small number of links - usually 3-5.
The total number of species in an ecosystem can be hundreds or thousands. Almost always, organisms of different species feed on different objects. As a result, a complex food web is formed. Thanks to this, the disappearance of individuals of any species does not affect the ecosystem. It continues to exist steadily for a long time.
The flows of substances and energy passing through living organisms are very large. So, a person in his life consumes tens of tons of water and food, and many millions of liters of air pass through the lungs.
By origin
Ecosystems can be natural (forest, meadow, lake) and artificial (park, field, garden). Material from the site
To size
Ecosystems can be very large (tundra, taiga), middle sizes (reservoir, birch grove) and completely small (stream, bog hummock).
Ecosystem and its properties
Introduction
Word "ecology"formed from two Greek words: "oicos", which means home, dwelling, and "logos" - science and literally translated as the science of home, habitat. For the first time this term was used by the German zoologist Ernst Haeckel in 1886, defining ecology as a field of knowledge that studies the economics of nature - the study of the general relationship of animals with both living and inanimate nature, including all both friendly and unfriendly relations with which animals and plants come into direct or indirect contact. This understanding of ecology has become generally accepted and today classical ecology is the science of studying the relationship of living organisms with their environment. Living matter so diversethat it is studied at different levels of the organization and from different angles. The levels of organisms, populations and ecosystems are an area of \u200b\u200binterest for classical ecology. Depending on the object of research and the angle of view from which it is studied, independent scientific directions have formed in ecology. By the dimension of the objects of study, ecology is divided into autecology (an organism and its environment), population ecology (a population and its environment), synecology (communities and their environment), biogeocytology (the doctrine of ecosystems) and global ecology (the doctrine of the Earth's biosphere). Depending on the object of study, ecology is subdivided into ecology of microorganisms, fungi, plants, animals, humans, agroecology, industrial (engineering), human ecology, etc. By environments and components, the ecology of land, fresh water bodies, the sea, deserts, highlands and other environmental and geographical spaces is distinguished. Ecology is often referred to a large number of related branches of knowledge, mainly from the field of environmental protection. In this paper, first of all, the foundations of general ecology are considered, that is, the classical laws of the interaction of living organisms with the environment.
Ecosystem - the basic concept of ecology
Ecology considersinteraction of living organisms and inanimate nature. This interaction, firstly, takes place within a certain system (ecological system, ecosystem) and, secondly, it is not chaotic, but organized in a certain way, subject to laws. An ecosystem is a set of producers, consumers and detritus feeders interacting with each other and with their environment through the exchange of matter, energy and information in such a way that this unified system remains stable for a long time. Thus, a natural ecosystem is characterized by three features:
1) an ecosystem is necessarily a collection of living and nonliving components
2) within the ecosystem, a full cycle is carried out, starting with the creation of organic matter and ending with its decomposition into inorganic components;
3) the ecosystem remains stable for some time, which is provided by a certain structure of biotic and abiotic components.
Examples of natural ecosystems are lake, forest, desert, tundra, land, ocean, biosphere. As you can see from the examples, simpler ecosystems are included in more complexly organized ones. At the same time, the hierarchy of the organization of systems is implemented, in this case ecological. Thus, the device of nature should be considered as a systemic whole, consisting of nested ecosystems, the highest of which is a unique global ecosystem - the biosphere. Within its framework, there is an exchange of energy and matter between all living and nonliving components on a planetary scale. The catastrophe that threatens all of humanity is that one of the signs that an ecosystem should have is violated: the biosphere as an ecosystem is brought out of the state of stability by human activity. Due to its scale and variety of interconnections, it should not die from this, it will pass into a new stable state, while changing its structure, first of all inanimate, and after it inevitably also living. Man as a biological species has the least chance of adapting to new rapidly changing external conditions and is likely to disappear first. The history of Easter Island is an instructive and illustrative example of this. On one of the Polynesian islands, which bears the name of Easter Island, as a result of complex migration processes in the 7th century, a closed civilization isolated from the whole world arose. In a favorable subtropical climate, over hundreds of years of existence, it has reached certain heights of development, creating a self-life culture and writing that has not been deciphered to this day. And in the 17th century, she died without a trace, destroying at first the plant and animal world islands, and then destroying themselves in progressive savagery and cannibalism. The last islanders no longer had the will and the material to build the saving "Noah's arks" - boats or rafts. In memory of itself, the disappeared community left a semi-desert island with giant stone figures - witnesses of its former power. So, the ecosystem is the most important structural unit of the structure of the surrounding world. As seen from Fig. 1 (see Appendix), ecosystems are based on living matter, characterized by a biotic structure, and a habitat determined by a combination of environmental factors. Let's consider them in more detail.
Biotic structure of ecosystems
The ecosystem is based on the unity of living and nonliving matter. The essence of this unity is manifested in the following. From the elements of inanimate nature, mainly CO2 and H2O molecules, under the influence of the sun's energy, organic substances are synthesized, which make up all life on the planet. The process of creating organic matter in nature occurs simultaneously with the opposite process - the consumption and decomposition of this substance again into the original non organic compounds... The totality of these processes takes place within ecosystems at various levels of the hierarchy. For these processes to be balanced, nature has worked out a certain structure of the living matter of the system over billions of years. Energy is the driving force in any material system. It comes to ecosystems mainly from the Sun... Plants, due to the chlorophyll pigment they contain, capture the energy of the sun's radiation and use it to synthesize the basis of any organic substance - glucose C6H12O6.
The kinetic energy of solar radiation is thus converted into potential energy stored by glucose. All tissues of the plant world - proteins, carbohydrates, fats, lipids, DNA, RNA, that is, the organic matter of the planet - are formed from glucose together with the mineral nutrients obtained from the soil - biogens.
In addition to plants, some bacteria can produce organic matter.... They create their tissues, storing in them, like plants, potential energy from carbon dioxide without the participation of solar energy. Instead, they use the energy that is formed during the oxidation of inorganic compounds, for example, ammonia, iron, and especially sulfur (unique ecosystems have been found in deep oceanic trenches, where sunlight does not penetrate, but where hydrogen sulfide accumulates in abundance). This is the so-called energy of chemical synthesis, which is why organisms are called chemosynthetics. Thus, plants and chemosynthetics create organic matter from inorganic constituents using the energy of the environment. They are called producers or autotrophs. The release of the potential energy stored by producers ensures the existence of all other living species on the planet. Species that consume organics created by producers as a source of matter and energy for their vital activity are called consumers or heterotrophs. Consumations - these are the most diverse organisms (from microorganisms to blue whales): protozoa, insects, reptiles, fish, birds and, finally, mammals, including humans. Consumables, in turn, are subdivided into a number of subgroups according to the differences in their food sources. Animals that feed directly on producers are called primary consumers or first-order consumers. They themselves are eaten by secondary consumers. For example, a rabbit eating a carrot is a first-order consumer, and a fox hunting a rabbit is a second-order consumer. Some types of living organisms correspond to several of these levels. For example, when a person eats vegetables, he is a first-order consumer, beef is a second-order consumer, and when he eats predatory fish, he acts as a third-order consumer.
Primary consumers eating only plants are called herbivorous or phytophages. Consumations second and higher orders - carnivores. The species that eat both plants and animals are omnivores, such as humans. Dead plant and animal debris, such as fallen leaves, animal carcasses, products of excretory systems, are called detritus. It's organic! There are many organisms that specialize in feeding on detritus. They are called detritus feeders. Examples include vultures, jackals, worms, crayfish, termites, ants, etc. As in the case of ordinary consumers, there are primary detritivores feeding directly on detritus, secondary ones, etc. Finally, a significant part of detritus in the ecosystem, in particular fallen leaves, dead wood, in its original form is not eaten by animals, but rot and decomposes into the process of feeding them to fungi and bacteria. Since the role of fungi and bacteria is so specific, they are usually isolated into a special group of detritivores and are called reducers. Reducers serve as orderlies on Earth and close the biogeochemical circulation of substances, decomposing organic matter into the original inorganic components - carbon dioxide and water. Thus, despite the diversity of ecosystems, they all have structural similarities. In each of them, photosynthetic plants - producers, various levels of consumers, detritivores and decomposers can be distinguished. They constitute the biotic structure of ecosystems.
Environmental factors
Unliving and live naturesurrounding plants, animals and humans is called the habitat. Many of the individual components of the environment that affect organisms are called environmental factors. By the nature of origin, abiotic, biotic and anthropogenic factors are distinguished. Abiotic factors are properties of inanimate nature that directly or indirectly affect living organisms. Biotic factors are all forms of influence of living organisms on each other. Previously, the impact of humans on living organisms was also referred to as biotic factors, but now a special category of factors generated by humans is distinguished. Anthropogenic factors are all forms of human society activity that lead to changes in nature as a habitat and other species and directly affect their lives. Thus, every living organism is influenced by inanimate nature, organisms of other species, including humans, and, in turn, affects each of these components.
The laws of the impact of environmental factors on living organisms
Despite the variety of environmental factors and the different nature of their origin, there are some general rules and the patterns of their impact on living organisms. A certain combination of conditions is necessary for the life of organisms. If all environmental conditions are favorable, with the exception of one, then it is this condition that becomes decisive for the life of the organism in question. It limits (limits) the development of the organism, therefore it is called a limiting factor. Initially it was found that the development of living organisms is limited by the lack of any component, for example, mineral salts, moisture, light, etc. In the middle of the 19th century, the German chemical organic Eustace Liebig was the first to experimentally prove that the growth of a plant depends on a nutrient that is present in a relatively minimal amount. He called this phenomenon the law of minimum; in honor of the author, it is also called Liebig's law. In the modern formulation, the law of minimum sounds like this: the endurance of an organism is determined by the weakest link in the chain of its ecological needs. However, as it turned out later, the limiting factor may be not only a deficiency, but also an excess of a factor, for example, crop loss due to rains, soil oversaturation with fertilizers, etc. The notion that, along with the minimum, the maximum can be a limiting factor was introduced 70 years after Liebig by the American zoologist W. Shelford, who formulated the law of tolerance. According to the law of tolerance, the limiting factor for the prosperity of a population (organism) can be at least and a maximum of environmental impact, and the range between them determines the value of endurance (tolerance limit) or the environmental valence of an organism to this factor. The favorable range of action of the environmental factor is called the zone of optimum (normal life activity). The more significant the deviation of the factor from the optimum, the more this factor inhibits the vital activity of the population. This range is called the zone of oppression. The maximum and minimum tolerable values \u200b\u200bof a factor are critical points beyond which the existence of an organism or a population is no longer possible. In accordance with the law of tolerance, any excess of matter or energy turns out to be a polluting principle. For example, excess water, even in arid regions, is harmful and water can be considered as a common pollutant, although in optimal quantities it is simply necessary. In particular, excess water prevents normal soil formation in the chernozem zone. Species, for the existence of which strictly defined ecological conditions are required, are called stenobiotic, and species that adapt to the ecological situation with a wide range of changes in parameters are called eurybiotic. Among the laws that determine the interaction of an individual or an individual with his environment, let us single out the rule of compliance of environmental conditions with the genetic predetermination of an organism. It argues that a species of organisms can exist as long and insofar as the natural environment surrounding it corresponds to the genetic ability of this species to adapt to its fluctuations and changes.
Abiotic factors of the environment
Abiotic factors - these are the properties of inanimate nature, which directly or indirectly affect living organisms. In fig. 5 (see Appendix) shows the classification of abiotic factors. Let's start with the climatic factors of the external environment. Temperature is the most important climatic factor. The intensity of metabolism of organisms and their geographical distribution depend on it. Any organism is capable of living within a certain temperature range. And although these intervals are different for different types of organisms (eurythermal and stenothermal), for most of them the zone of optimal temperatures, at which vital functions are carried out most actively and efficiently, is relatively small. The temperature range in which life can exist is approximately 300 ° C: from -200 to + 100 ° C. But most species and most of the activity are confined to an even narrower temperature range. Certain organisms, especially in the dormant stage, can exist for at least some time, at very low temperatures. Certain types of microorganisms, mainly bacteria and algae, are able to live and reproduce at temperatures close to the boiling point. The upper limit for hot spring bacteria is 88 C, for blue-green algae - 80 C, and for the most resistant fish and insects - about 50 C. As a rule, the upper limit values \u200b\u200bof the factor turn out to be more critical than the lower ones, although many organisms are near the upper limits of the tolerance range function more efficiently. In aquatic animals, the range of temperature tolerance is usually narrower than in land animals, since the range of temperature fluctuations in water is less than on land. Thus, temperature is an important and very often limiting factor. Temperature rhythms largely control the seasonal and daily activity of plants and animals.
Rainfall and humidity - the main quantities measured when studying this factor. The amount of precipitation depends mainly on the paths and the nature of large movements of air masses. For example, winds blowing from the ocean leave most of the moisture on the ocean-facing slopes, leaving a "rain shadow" behind the mountains, contributing to desert formation. Moving inland, the air accumulates some moisture, and the amount of precipitation increases again. Deserts tend to be located behind high mountain ranges or along coastlines where winds blow from vast inland dry areas rather than from the ocean, such as the Nami Desert in South West Africa. The distribution of precipitation across seasons is an extremely important limiting factor for organisms. Humidity is a parameter that characterizes the content of water vapor in the air. Absolute humidity is the amount of water vapor per unit volume of air. In connection with the dependence of the amount of steam held by the air on temperature and pressure, the concept of relative humidity has been introduced - this is the ratio of steam contained in the air to saturating steam at a given temperature and pressure. Since in nature there is a daily rhythm of humidity - an increase at night and a decrease during the day, and its fluctuations vertically and horizontally, this factor, along with light and temperature, plays an important role in regulating the activity of organisms. Surface water reserve available to living organisms depends on the amount of precipitationin this area, but these values \u200b\u200bdo not always coincide. So, using underground sources, where water comes from other areas, animals and plants can receive more water than from its input with precipitation. Conversely, rainwater sometimes becomes immediately inaccessible to organisms. Radiation from the Sun is electromagnetic waves of various lengths. It is absolutely necessary for living nature, as it is the main external source of energy. It should be borne in mind that the spectrum of the Sun's electromagnetic radiation is very wide and its frequency ranges affect living matter in different ways.
For living matter, the qualitative characteristics of light are important - wavelength, intensity and duration of exposure. Ionizing radiation knocks electrons out of atoms and attaches them to other atoms to form pairs of positive and negative ions. Its source is radioactive substances contained in rocks, in addition, it comes from space. Different types of living organisms differ greatly in their ability to withstand large doses of radiation exposure. As the data of most of the studies show, rapidly dividing cells are most sensitive to radiation. In higher plants, sensitivity to ionizing radiation is directly proportional to the size of the cell nucleus, or rather to the volume of chromosomes or DNA content. The gas composition of the atmosphere is also an important climatic factor. About 3-3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases. Due to the lack of oxygen, there was no ozone screen that trapped the sun's ultraviolet radiation. Over time, due to abiotic processes, oxygen began to accumulate in the planet's atmosphere, and the formation of the ozone layer began. Wind can even change the appearance of plants, especially in those habitats, for example, in alpine zones, where other factors have a limiting effect. It has been shown experimentally that in open mountain habitats the wind limits the growth of plants: when a wall was built to protect plants from the wind, the height of the plants increased. Storms are of great importance, although their action is purely local. Hurricanes and ordinary winds can carry animals and plants over long distances and thus alter the composition of communities. Atmospheric pressure does not appear to be a direct limiting factor, but it is directly related to weather and climate, which have a direct limiting effect.
Water conditions create a kind of habitat for organisms, which differs from the ground primarily in density and viscosity. The density of water is about 800 times and the viscosity is about 55 times that of air. Together with the density and viscosity, the most important physicochemical properties of the aquatic environment are: temperature stratification, that is, the change in temperature along the depth of the water body and periodic changes in temperature over time, as well as the transparency of water, which determines the light regime under its surface: the photosynthesis of green and purple algae, phytoplankton, higher plants. As in the atmosphere, the gas composition of the aquatic environment plays an important role. In aquatic habitats, the amount of oxygen, carbon dioxide and other gases dissolved in water and therefore available to organisms varies greatly over time. In reservoirs with a high organic content, oxygen is the limiting factor of paramount importance. Acidity - the concentration of hydrogen ions (pH) - is closely related to the carbonate system. The pH value ranges from 0 pH to 14: at pH \u003d 7 the medium is neutral, at pH<7 - кислая, при рН>7 - alkaline. If the acidity does not approach extreme values, then the communities are able to compensate for changes in this factor - the community's tolerance to the pH range is very significant. The waters with low pH contain few nutrients, so the productivity is extremely low. Salinity - the content of carbonates, sulfates, chlorides, etc. - is another significant abiotic factor in water bodies. There are few salts in fresh waters, of which about 80% are carbonates. The content of minerals in the oceans averages 35 g / l. The organisms of the open ocean are usually stenohaline, while the organisms of coastal brackish waters are generally euryhaline. The concentration of salts in body fluids and tissues of most marine organisms is isotonic to the concentration of salts in sea \u200b\u200bwater, so there are no problems with osmoregulation. The flow not only strongly affects the concentration of gases and nutrientsbut also directly acts as a limiting factor. Many river plants and animals are morphologically and physiologically adapted in a special way to maintain their position in the flow: they have quite definite limits of tolerance to the flow factor. The hydrostatic pressure in the ocean is of great importance. When immersed in water for 10 m, the pressure increases by 1 atm (105 Pa). In the deepest part of the ocean, the pressure reaches 1000 atm (108 Pa). Many animals are able to withstand sudden pressure fluctuations, especially if they have no free air in their body. Otherwise, gas embolism may develop. High pressures characteristic of great depths, as a rule, inhibit vital processes.
The soil
Soil is the layer of matter lying on top of rocks. crust
... Russian scientist - naturalist Vasily Vasilievich Dokuchaev in 1870, he was the first to consider soil as a dynamic rather than inert medium. He proved that the soil is constantly changing and developing, and chemical, physical and biological processes take place in its active zone. Soil is formed as a result of a complex interaction of climate, plants, animals and microorganisms. The composition of the soil consists of four main structural components: mineral base (usually 50-60% of the total soil composition), organic matter (up to 10%), air (15-25%) and water (25-30%). The mineral skeleton of the soil is an inorganic component that was formed from the parent rock as a result of its weathering. Soil organic matter is formed by the decomposition of dead organisms, their parts and excrement. Incompletely decomposed organic residues are called bedding, and the end product of decomposition - an amorphous substance in which it is no longer possible to recognize the original material - is called humus.Due to its physical and chemical properties, humus improves soil structure and aeration, as well as increases the ability to retain water and nutrients. The soil is inhabited by many species of plant and animal organisms that affect its physical and chemical characteristics: bacteria, algae, fungi or protozoa, worms and arthropods. Their biomass in different soils is (kg / ha): bacteria 1000-7000, microscopic fungi - 100-1000, algae 100-300, arthropods - 1000, worms 350-1000. The main topographic factor is altitude. Average temperatures decrease with height, daily temperature drop increases, precipitation, wind speed and radiation intensity increase, atmosphere pressure and gas concentration. All of these factors affect plants and animals, causing vertical zoning. Mountain ranges can serve as climatic barriers. Mountains also serve as barriers to the spread and migration of organisms and can play the role of a limiting factor in the processes of speciation.
Another topographic factor is slope exposure. In the northern hemisphere, south-facing slopes receive more sunlight, so the light intensity and temperature are higher here than at the bottom of the valleys and on the north-facing slopes. The opposite is true in the southern hemisphere. The steepness of the slope is also an important relief factor. The steep slopes are characterized by rapid drainage and soil washout, so the soils are thinner and drier. For abiotic conditions, all the considered laws of the impact of environmental factors on living organisms are valid. Knowledge of these laws allows us to answer the question: why did different ecosystems form in different regions of the planet? The main reason is the uniqueness of the abiotic conditions of each region.
Biotic relationships and the role of species in the ecosystem
Distribution areas and number of organisms of each speciesare limited not only by the conditions of the external inanimate environment, but also by their relationship with organisms of other species. The immediate living environment of an organism constitutes its biotic environment, and the factors of this environment are called biotic. Representatives of each species are able to exist in such an environment where connections with other organisms provide them with normal living conditions. Consider the characteristic features of relationships of various types. Competition is in nature the most all-encompassing type of relationship, in which two populations or two individuals, in the struggle for the conditions necessary for life, affect each other negatively. Competition can be intraspecific and interspecific. Intraspecific struggle occurs between individuals of the same species, interspecies competition takes place between individuals of different species. Competitive interaction can relate to living space, food or nutrients, light, shelter and many other vital factors. Interspecific competition, regardless of what underlies it, can lead either to the establishment of an equilibrium between two species, or to the replacement of the population of one species with a population of another, or to the fact that one species will displace the other to another place or force it to switch to use of other resources. It has been established that two species that are ecologically identical and in needs cannot coexist in one place and sooner or later one competitor displaces the other. This is the so-called exclusion principle or Gause principle.
1) the relationship between living organisms is one of the main regulators of the number and spatial distribution of organisms in nature;
2) negative interactions between organisms are manifested at the initial stages of community development or in disturbed natural conditions; in newly formed or new associations, the likelihood of strong negative interactions is greater than in old associations;
3) in the process of evolution and development of ecosystems, there is a tendency towards a decrease in the role of negative interactions due to positive ones that increase the survival of interacting species.
All these circumstances, a person must take into account when carrying out measures for the management of ecological systems and individual populations in order to use them in their own interests, as well as foresee the indirect consequences that may occur in this case.
Ecosystem functioning
Energy in ecosystems.
Recall that an ecosystem is a collection of living organisms, exchanging energy, substance and information with each other and with the environment. Let us first consider the process of energy exchange. Energy is defined as the ability to do work. Energy properties are described by the laws of thermodynamics.
The first law (beginning) of thermodynamics or the law of conservation of energy states that energy can pass from one form to another, but it does not disappear and is not created anew. The second law (beginning) of thermodynamics or the law of entropy states that in a closed system, entropy can only increase. With regard to energy in ecosystems, the following formulation is convenient: the processes associated with energy transformations can occur spontaneously only if the energy passes from a concentrated form to a scattered one, that is, degrades. The measure of the amount of energy that becomes unavailable for use, or otherwise the measure of the change in order that occurs during the degradation of energy, is entropy. The higher the ordering of the system, the lower its entropy. Thus, any living system, including an ecosystem, maintains its vital activity due, firstly, to the presence in environment in excess of free energy (energy of the Sun); secondly, the ability, due to the device of its constituent components, to capture and concentrate this energy, and, using it, to dissipate it into the environment. Thus, first capturing and then concentrating energy with the transition from one trophic level to another provides an increase in orderliness, organization of a living system, that is, a decrease in its entropy.
Energy and productivity of ecosystems
So, life in an ecosystem is maintained thanks to the incessant passage of energy through living matter, transferred from one trophic level to another; at the same time, there is a constant transformation of energy from one form to another. In addition, during the transformation of energy, part of it is lost in the form of heat.
Then the question arises: in what quantitative ratios, proportions should the members of the community of different trophic levels in the ecosystem be among themselves in order to ensure their need for energy?
All energy reserves are concentrated in the mass of organic matter - biomass, therefore the intensity of the formation and destruction of organic matter at each of the levels is determined by the passage of energy through the ecosystem (biomass can always be expressed in units of energy). The rate of formation of organic matter is called productivity. Distinguish between primary and secondary productivity. In any ecosystem, biomass is formed and destroyed, and these processes are entirely determined by the life of the lowest trophic level - producers. All other organisms only consume the organic matter already created by plants and, therefore, the overall productivity of the ecosystem does not depend on them. High rates of biomass production are observed in natural and artificial ecosystems where abiotic factors are favorable, and especially when additional energy is supplied from the outside, which reduces the system's own costs for maintaining life. This additional energy can come in different forms, for example, in the cultivated field, in the form of fossil fuel energy and work done by humans or animals. Thus, to provide energy to all individuals of the community of living organisms in the ecosystem, a certain quantitative ratio between producers, consumers of different orders, detritivores and decomposers. However, for the life of any organisms, and therefore the system as a whole, only energy is not enough, they must necessarily receive various mineral components, trace elements, organic substances necessary to build molecules of living matter.
Cycle of elements in the ecosystem
Where do the components necessary for building an organism come from in a living substance? They are supplied to the food chain by the same producers. They extract inorganic minerals and water from the soil, CO2 from the air, and from the glucose formed in the process of photosynthesis with the help of biogens, they further build complex organic molecules - carbohydrates, proteins, lipids, nucleic acids, vitamins, etc. In order for the necessary elements to be available to living organisms, they must be available at all times. In this relationship, the law of conservation of matter is realized. It is convenient to formulate it as follows: atoms in chemical reactions never disappear, do not form and do not transform into each other; they only rearrange with the formation of various molecules and compounds (energy is absorbed or released simultaneously). Because of this, atoms can be used in a wide variety of compounds and their supply is never depleted. This is what happens in natural ecosystems in the form of cycles of elements. At the same time, there are two cycles: large (geological) and small (biotic). The water cycle is one of the greatest processes on the surface of the globe. It plays a major role in linking the geological and biotic cycles. In the biosphere, water, continuously passing from one state to another, makes small and large cycles. Evaporation of water from the ocean surface, condensation of water vapor in the atmosphere, and precipitation on the ocean surface form a small cycle. If water vapor is carried by air currents to land, the cycle becomes much more difficult. In this case, part of the precipitation evaporates and flows back into the atmosphere, while the other part feeds rivers and water bodies, but eventually returns to the ocean again by river and underground runoff, thereby completing the large cycle. An important property of the water cycle is that, interacting with the lithosphere, atmosphere and living matter, it binds together all parts of the hydrosphere: the ocean, rivers, soil moisture, groundwater and atmospheric moisture. Water is the most important component of all living things. Ground water, penetrating through plant tissues in the process of transpiration, brings in mineral salts necessary for the life of the plants themselves. Summarizing the laws of ecosystem functioning, let us formulate once again their main provisions:
1) natural ecosystems exist at the expense of non-polluting free solar energy, the amount of which is excessive and relatively constant;
2) the transfer of energy and matter through the community of living organisms in the ecosystem occurs along the food chain; all species of life in the ecosystem are divided according to their functions in this chain into producers, consumers, detritus feeders and decomposers - this is the biotic structure of the community; the quantitative ratio of the number of living organisms between trophic levels reflects the trophic structure of the community, which determines the rate of passage of energy and matter through the community, that is, the productivity of the ecosystem;
3) natural ecosystems, thanks to their biotic structure, maintain a stable state indefinitely without suffering from resource depletion and pollution by their own waste; the receipt of resources and disposal of waste occur within the framework of the cycle of all elements.
Human impact on the ecosystem
The impact of man on his natural environment can be considered in different aspects depending on the purpose of studying this issue. From the point of view of ecology, it is of interest consideration of human exposure on ecological systems from the point of view of compliance or contradiction of human actions with the objective laws of the functioning of natural ecosystems. Based on the view of the biosphere as a global ecosystem, all the diversity of human activities in the biosphere leads to changes: the composition of the biosphere, cycles and the balance of its constituent substances; energy balance of the biosphere; biota. The direction and degree of these changes are such that man himself has given them the name of the ecological crisis. The current ecological crisis is characterized by the following manifestations:
A gradual change in the planet's climate due to a change in the balance of gases in the atmosphere;
- general and local (over the poles, individual land areas) destruction of the biospheric ozone screen;
- pollution of the oceans with heavy metals, complex organic compounds, oil products, radioactive substances, saturation of water with carbon dioxide;
- the rupture of natural ecological ties between the ocean and land waters as a result of the construction of dams on rivers, leading to a change in solid runoff, spawning routes, etc .;
- air pollution with the formation of acid precipitation, highly toxic substances as a result of chemical and photochemical reactions;
- pollution of onshore waters, including river waters used for drinking water supply, with highly toxic substances, including dioxins, heavy metals, phenols;
- desertification of the planet;
- degradation of the soil layer, a decrease in the area of \u200b\u200bfertile lands suitable for agriculture;
- radioactive contamination of certain territories in connection with the disposal of radioactive waste, man-made accidents, etc .;
- accumulation of household waste and industrial waste on the land surface, especially practically non-degradable plastics;
- reduction in the areas of tropical and northern forests, leading to an imbalance of atmospheric gases, including a reduction in the concentration of oxygen in the planet's atmosphere;
- pollution of underground space, including groundwater, which makes them unsuitable for water supply and threatens the still poorly studied life in the lithosphere;
- massive and rapid, avalanche-like disappearance of species of living matter;
- deterioration of the living environment in populated areas, primarily urbanized areas;
- general depletion and lack of natural resources for human development;
- change in the size, energy and biogeochemical role of organisms, reorganization of food chains, massive reproduction of certain types of organisms;
- violation of the hierarchy of ecosystems, an increase in systemic uniformity on the planet.
Conclusion
When, in the mid-sixties of the twentieth century, environmental problems became the focus of the world's attention, the question arose: how much time does humanity have in stock? When will it begin to reap the benefits of neglecting its environment? Scientists calculated: in 30-35 years. This time has come. we witnessed a global environmental crisis, provoked by human activity. However, the past thirty years have not been in vain: a more solid scientific basis for understanding environmental problems has been created, regulatory bodies have been formed at all levels, numerous environmental public groups have been organized, useful laws and regulations have been adopted, and some international agreements have been reached. However, it is mainly the consequences that are eliminated, not the causes of the current situation. For example, people are using more and more pollution control measures on their cars and trying to extract more oil instead of questioning the very need to satisfy excessive needs. Humanity desperate to save from extinction of several species, not paying attention to their own population explosion, which erases natural ecosystems from the face of the earth. The main conclusion from the material considered in the textbook is quite clear: systems that contradict natural principles and laws are unstable. Attempts to preserve them are becoming more costly and difficult, and are doomed to failure in any case. In order to make long-term decisions, it is necessary to pay attention to the principles that define sustainable development, namely:
Stabilization of the population;
- transition to a more energy and resource-saving lifestyle;
- development of clean energy sources;
- creation of low-waste industrial technologies;
- waste recycling;
- creation of a balanced agricultural production that does not deplete soil and water resources and does not pollute land and food;
- conservation of biological diversity on the planet.
List of references
1. Nebel B. Environmental Science: How the World Works: In 2 volumes - M.: Mir, 1993.
2. Odum Y. Ecology: In 2 volumes - M .: Mir, 1986.
3. Reimers NF Conservation of nature and human environment: Dictionary-reference book. - M.: Education, 1992 .-- 320 p.
4. Stadnitsky GV, Rodionov AI Ecology.
5. M .: Higher. shk., 1988 .-- 272 p.
Just as people live in houses and apartments, so nature has its own separate systems from others. They are isolated and, one might say, independent. They are called ecosystems and include many different organisms. In addition, they are subject to certain laws. In this article, we will look at what ecosystems are: concept, structure, purpose. We will also tell you what they include.
Concept
A set of organisms living together in a certain habitat and interacting with each other in one way or another is designated by the term "ecosystem". This concept was proposed in 1935 by the English scientist A. Tensley. He was engaged in research on the relationship of organisms and their joint development. By the way, it is he who is considered one of the founders of such a science as ecology, which deals with the study of what an ecosystem is. The ecosystem structure is represented by two main components: biocenosis and biotope. The first refers to the organisms themselves and their interconnections, and the second refers to the habitat. As a rule, a full set of living things participate in an ecosystem: from bacteria to higher animals. And what is surprising is that the whole community is in balance, which, when disturbed, is restored again, and each of its members performs extremely important functions.
Biogeocenosis
The collection of some components, exchanging energy and capable of more or less, is an ecosystem. The structure of an ecosystem assumes the presence of all major organisms: bacteria, plants, animals, fungi. But some of them may be missing. In this situation, it makes sense to separate this concept from biogeocenosis. This term means a community that has all of the above components. Moreover, the biotic structure of an ecosystem can include only one participant, for example, only bacteria. This situation can be observed in communities formed, for example, on the basis of animal corpses. Thus, ecosystem and biogeocenosis are not synonyms, because the latter is a broader concept. Despite this, they are often confused.
Classification and structuring
In addition to the fact that scientists share ecosystems among themselves according to some criteria, they are also interested in them. internal device... Different approaches and points of view add up to a fairly complete picture that allows you to consider each element separately. It is not surprising that so many criteria are used in structuring: type of food and function, species, location of participants. Of course, it is worth considering the most important of the factors in more detail, because the ecological structure of an ecosystem without talking, for example, about its composition, makes little sense.
As for the division of communities among themselves, as a rule, the main criterion is the prevailing environment. Another important feature is the naturalness of its origin and the ability to autonomously maintain functioning. Here we are talking primarily about interference with the nature of the human factor, which also makes sense to designate in more detail, but later.
By function
The trophic structure of the ecosystem differentiates the organisms participating in it by the type of nutrition. According to the cycle of substances in nature, nothing is taken from emptiness and cannot just disappear. Obviously, the matter is only in how these or those matters are transformed. And here two opposite groups of organisms come into play: autotrophs and heterotrophs. The latter are animals and mushrooms that consume organic matter. The former (plants and bacteria) do exactly the opposite. By the way, they, in turn, are divided into photosynthetics and chemosynthetics.
The functional structure of the ecosystem assumes the same division, but under different names. Here we are talking about producers, reducers, consumers and destructors. These two approaches are closely related to the concept of food webs.
By hierarchy
Naturally, any system of such complexity is divided into several levels. The first and most comprehensive is the already mentioned biocenosis, which is the totality of all participating living organisms. Further, ecosystems assumes division into phyto-, zoo-, myco- and microbocenosis. Each of these individual groups contains a population called a population. Finally, the smallest unit is the individual (or individual), which is a separate instance.
There is also a functional hierarchy. The trophic structure of the ecosystem, as already mentioned, presupposes division into producers, consumers, reducers, and destructors. But there are several levels here too. So, it all starts with green plants, which receive minerals and water from the soil, as well as sunlight. Herbivores are already level 1 consumers and consume greens for food. In turn, they serve as food for predators one step higher. So here, too, you can see its own special hierarchy.
By types
Even within the same type of organisms, there can be a certain variety, and this is not surprising. The species structure of an ecosystem is important indicator, reflecting the ratio of certain plants, animals, fungi, microorganisms, etc. This characteristic depends on a large number of factors: geographical location, climatic zone, water regime, age of the community. Similar species compositions can be observed thousands of kilometers from each other, if the main indicators in them are similar. In addition to the very presence of certain organisms, their number is also important. The most common representatives of living nature in a particular ecosystem are called environment-formers and, accordingly, perform key functions and create conditions for the survival of other species.
However, this does not mean that small participants are not very important. On the contrary, in a number of cases, a special biotic structure of ecosystems can provide very accurate information about its state. The presence of rare specimens of plants and animals can make it possible to understand, for example, how clean water and air are.
Spatially
At first glance, the division of ecosystems related to their location is quite obvious. Steppe, forest, desert, tundra - the set of organisms living here, no doubt, will be completely different. But such a classification is only relevant when it comes to comparing several systems and the differences between them.
On the other hand, each individual community will have its own physical hierarchy. The spatial structure of an ecosystem in a forest, for example, is easily noticeable; it is divided into several levels. Nightingales make nests in taller trees, while wagtails prefer to stay close to the ground. Even among vegetation, the inequality is obvious: trees, shrubs, grass and moss are located at completely different levels. Scientists call the combination of these characteristics tier, or number of storeys.
Terrestrial ecosystem
The structure of an ecosystem located on land can be very different, but almost always extremely interesting. They are found everywhere: in forests, steppes, deserts, high in the mountains, and each of them is curious in its own way. All of them are united by a ground-air habitat. Meanwhile, there may be even more differences in them than in common. For example, the structure of a forest ecosystem in the tropics will be completely different from what is observed in central Russia. Moreover, the green area in South America will be strikingly different from the picture in Southwest Asia. As already mentioned, the climatic zone is one of the main, but not the only factor influencing how an ecosystem develops. The structure of the ecosystem is too complex and multidimensional, and therefore delightful and mysterious.
Water
Freshwater and marine organisms, algae, plankton, jellyfish, deep-sea fish - the species structure of the ecosystem located in the world's oceans is no less interesting than the terrestrial one. It can often be much more complicated. The structure of an aquatic ecosystem in some features may resemble a terrestrial one, for example, there is also tiering here. But there is also a very important difference. It consists in the fact that the biomass pyramid is inverted here. This means that the primary producers (here it is a diverse plankton) are much more numerous and reproduce faster than consumers or consumers. This primarily concerns the sea and ocean depths, but the same situation can be observed in freshwater communities. The most interesting thing is that the structure of the aquatic ecosystem includes both some of the smallest organisms and the largest. And they all live peacefully in the neighborhood with each other.
Value
The importance of ecosystems can hardly be overestimated. First, they are all interconnected by the cycle of substances in nature. Elements from some systems fall into others, so they are also interdependent. Secondly, they allow more or less preservation of biodiversity - each community of organisms is unique, amazing and beautiful in its own way. Finally, all those natural resourceswhich a person receives without hesitation - clean water, agricultural land, fertile soil, fresh air - this or that ecosystem gives him. The structure of the ecosystem, like the entire biosphere, is rather fragile, so one should not forget about its role and sometimes one should think about the fact that the planet is worth preserving its wealth for posterity.
Anthropogenic factor
A person with his activities in one way or another affects almost all ecosystems. But if the influence on some of them is indirect, then others experience it directly. Deforestation of forests, soil and water, catching fish and animals - all this becomes a serious challenge for maintaining natural balance.
By the way, people continue to learn to model stable functioning ecosystems on their own, and also try to manage existing ones. As a rule, the life cycle of artificially created communities is not too long, and stability raises a lot of questions. However, it would be very useful to learn how to manage ecosystems, because in this way you could achieve greater productivity. agricultureand also try to restore what was destroyed. Unfortunately, so far it is assessed extremely negatively, because his actions cause a lot of consequences, in particular:
- climate change due to a shift in the gas composition of the atmosphere;
- reduction of forest areas;
- modification and destruction of unique communities and conditions;
- depletion of natural resources;
- desertification and;
- accumulation of household waste and environmental pollution;
- changes in the structure of ecosystems;
- thinning of the ozone layer.
It is worth thinking about the consumer attitude of humanity to the planet and reflecting on whether it is possible to preserve nature in its magnificent diversity. It's not so difficult to destroy, but will it be possible to create?
From an ecosystem point of view, a lake, forest or some other elements of nature seem to us to consist of two main components: autotrophic component (autotrophic means self-feeding), capable of fixing light energy and using simple inorganic substancesand gerotrophic component (heterotrophic means eating ready-made organic substances), which decomposes, rebuilds and uses complex substances synthesized by autotrophic organisms.
These functional components are located in the form of overlapping layers, with the greatest number of autotrophic organisms located in the upper layer, where light energy enters, while intense heterotrophic activity is concentrated in places where organic matter accumulates in the soil and in the silt.
From the point of view of structure, it is convenient to distinguish four components of the ecosystem: 1) abiotic substances - the main elements and components of the environment; 2) producers - producers, autotrophic elements (mainly green plants); 3) large consumers, or macro-consumables, are heterotrophic organisms (mainly animals that devour other organisms or grind organic matter); 4) decomposers, or micro-consumables (also called saprophytes or saprobic organisms), heterotrophic organisms (mainly bacteria and fungi) that decompose the complex components of dead protoplasm, absorb decay products and release simple substances used by producers.
These ecosystems are the most extreme types found in the biosphere; they strongly highlight the similarities and differences of all ecosystems. The terrestrial ecosystem (represented by the field shown on the left) and the open water system (represented by either the lake or the sea shown on the right) are inhabited by completely different organisms, with the exception, perhaps, of some bacteria that can live in both environments.
Despite this, in both types of ecosystems, the main ecological components are present and operate. On land, autotrophs are usually represented by large plants with roots; whereas in deep water bodies the role of autotrophs is taken on by microscopic plants suspended in water, which are called phytoplankton (phyton - plant; plankton - weighed). With a certain amount of light and minerals for a certain period of time, the smallest plants are able to form the same amount of food as large plants. Both types of producers provide life for the same number of consumers and decomposers. In the future, the similarities and differences between terrestrial and aquatic ecosystems will be analyzed in more detail.
In order to understand the relationship between structure and function, it is necessary to assess the structure of the ecosystem from different points of view. The relationship of producers and consumers is one type of structure called trophic (trophe - food), and each "food" level is called a trophic level. The amount of living material at different trophic levels or in a population is called “harvest in the field,” a term that applies equally to both plants and animals. “Field harvest” can be expressed either by the number of organisms per unit area, or by the amount of biomass, ie, the body weight of organisms (live weight, dry weight, dry weight without ash, carbon weight, calories), or in some or other units suitable for comparison purposes. “Harvest in the field” not only represents potential energy, but plays a large role in reducing fluctuations physical conditionsand also as a habitat, or living space, for organisms. Thus, the trees in the forest are not only energy stores that provide food or fuel, but also change the climate and create shelters for birds and people.
The amount of lifeless material, such as phosphorus, nitrogen, etc., available at a given time can be considered a state of stability, or a stable amount. It is necessary to distinguish between the quantities of materials and organisms available at a given point in time on average over a certain period, and the rate of change in the state of stability and "yield in the field" per unit of time. The functions of changing the speeds will be considered in detail after getting acquainted with some other aspects of the structure of the ecosystem.
The amount and distribution of both inorganic and organic matter, concentrated either in biomass or in the environment, should be considered an important characteristic of any ecosystem. About this in general form one could speak as a biochemical structure. For example, the knowledge of the amount of chlorophyll per unit of the earth's or water surface is of great ecological interest. It is also extremely important to know the amount of organic matter dissolved in the water. In addition, it is necessary to represent the species structure of the ecosystem. The ecological structure reflects not only the number of certain species, but also the species diversity of the ecosystem. The latter manifests itself in the form of relationships between species and the number of individuals or biomass and in the form of dispersion (spatial distribution) of individuals of all species that make up the community.
It should be emphasized that ecosystems can be limited to different sizes. The objects of study can be a small pond, a large lake, a patch of forest, and even a small aquarium. Any unit can be considered an ecosystem if it contains leading and interacting components that create functional stability at least for a short time. Our biosphere as a whole is a series of transitions - gradients (from mountains to valleys, from coasts to the depths of the sea, etc.), which together create a "chemostat", namely, constancy chemical composition air and water over a long period of time. It is not particularly important where to draw the boundaries between gradients, since the ecosystem is primarily a functional unity. It should, of course, be pointed out that in nature there are often discontinuities in gradients that provide convenient and functionally logical boundaries. So, for example, a lake shore can be understood as the correct boundary between two sharply different ecosystems, namely a lake and a forest. The larger and more diverse the ecosystem, the more stable it is and relatively independent of the action of adjacent systems. Thus, a lake as a whole can be considered as a more independent unit than a part of a lake; however, for research purposes, even a separate part of a lake can be considered an ecosystem.
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Ecological system
Ecosystem or ecological system (from the Greek óikos - dwelling, location and system), natural complex (bioinert system) formed by living organisms (biocenosis) and their habitat (inert, for example, the atmosphere, or bioinert - soil, water body, etc.), interconnected by the exchange of substances and energy. One of the basic concepts of ecology, applicable to objects of varying complexity and size. Examples of Ecosystems - a pond with plants, fish, invertebrates, microorganisms, bottom sediments inhabiting it, with characteristic changes in temperature, the amount of oxygen dissolved in water, water composition, etc., with a certain biological productivity; a forest with forest floor, soil, microorganisms, with birds, herbivorous and predatory mammals inhabiting it, with a characteristic distribution of temperature and humidity of air, light, soil water and other environmental factors, with its inherent metabolism and energy. A rotting stump in a forest, with organisms and living conditions living on it and in it, can also be considered as an Ecosystem
Basic information
An ecological system (ecosystem) is a set of populations of various types of plants, animals and microbes, interacting with each other and their environment in such a way that this set persists for an indefinitely long time. Examples of ecological systems: meadow, forest, lake, ocean. Ecosystems exist everywhere - in water and on land, in dry and humid areas, in cold and hot places. They look different and include different types of plants and animals. However, in the "behavior" of all ecosystems there are general aspectsassociated with the fundamental similarity of the energy processes occurring in them. One of the fundamental rules that all ecosystems obey is le Chatelier - Brown principle :
under an external influence that brings the system out of a state of stable equilibrium, this equilibrium shifts in the direction at which the effect of external influence is weakened.
When studying ecosystems, first of all, the flow of energy and the cycle of substances between the corresponding biotope and biocenosis are analyzed. The ecosystem approach takes into account the common organization of all communities, regardless of habitat. This confirms the similarity in the structure and functioning of terrestrial and aquatic ecosystems.
According to V.N.Sukachev's definition, biogeocenosis (from the Greek bios - life, ge - Earth, cenosis - society) - it is a set of homogeneous natural elements (atmosphere, rocks, vegetation, fauna and the world of microorganisms, soil and hydrological conditions) on a certain area of \u200b\u200bthe Earth's surface... The biogeocenosis contour is established along the border of the plant community (phytocenosis).
The terms "ecological system" and "biogeocenosis" are not synonymous. An ecosystem is any collection of organisms and their habitat, including, for example, a flower pot, an anthill, an aquarium, a swamp, manned spaceship... The listed systems lack a number of features from the definition of Sukachev, and first of all the “geo” element is the Earth. Biocenoses are only natural formations. However, the biocenosis can fully be considered as an ecosystem. Thus, the concept of "ecosystem" is broader and fully embraces the concept of "biogeocenosis", or "biogeocenosis" - this is a special case of "ecosystem".
The largest natural ecosystem on Earth is the biosphere. The border between a large ecosystem and the biosphere is just as arbitrary as between many concepts in ecology. The difference mainly consists in such a characteristic of the biosphere as globality and large conditional isolation (with thermodynamic openness). Other ecosystems of the Earth are practically not closed materially.
Ecosystem structure
Any ecosystem can be primarily divided into a set of organisms and a set of inanimate (abiotic) factors of the natural environment.
In turn, the ecotope consists of the climate in all its various manifestations and the geological environment (soils and grounds), called edaphotop. Edaphotop is where the biocenosis derives its means of subsistence and where it releases waste products.
The structure of the living part of the biogeocenosis is determined by trophoenergetic connections and relationships, in accordance with which three main functional components are distinguished:
complex autotrophic producer organisms that provide organic matter and, therefore, energy to other organisms (phytocenosis (green plants), as well as photo- and chemosynthetic bacteria); complex heterotrophic consumer organisms, living on nutrients created by producers; firstly, it is a zoocenosis (animals), and secondly, chlorophyll-free plants; complex decomposing organisms that decompose organic compounds to a mineral state (microbiocenosis, as well as fungi and other organisms that feed on dead organic matter).
As a visual model of the ecological system and its structure, Yu. Odum proposed using a spacecraft for long journeys, for example, to planets Solar system or even further. Leaving the Earth, people should have a clearly limited closed system that would provide all their vital needs, and use the energy of solar radiation as energy. Such a spacecraft should be equipped with systems for the complete regeneration of all vital abiotic components (factors), allowing their repeated use. It must carry out balanced processes of production, consumption and decomposition by organisms or their artificial substitutes. In fact, such an autonomous ship will be a microecosystem that includes humans.
Examples of
A section of a forest, a pond, a rotting stump, an individual inhabited by microbes or helminths are ecosystems. The concept of an ecosystem is thus applicable to any collection of living organisms and their habitats.
Literature
- N.I. Nikolaykin, N.E. Nikolaykina, O. P. Melekhova Ecology. - 5th. - Moscow: Bustard, 2006 .-- 640 p.
see also
Links
- Ecosystem - Ecology News
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