Ecosystems have acquired, politically, special relevance since the Convention on Biological Diversity (CBD) (or in English "Convention on Biological Diversity")[10]​—ratified by more than 175 countries in Rio de Janeiro in June 1992—establishes "the protection of ecosystems, natural habitats and the maintenance of viable populations of species in natural environments"[11]​ as a commitment of the ratifying countries. This has created a political need to spatially identify ecosystems and somehow distinguish between them. The CBD defines an "ecosystem" as "a dynamic complex of plant, animal and microorganism communities and their non-living environment that interact as a functional unit."[12]​.

With the need to protect ecosystems comes the political need to describe and identify them efficiently. Vreugdenhil et al. They argued that this could be achieved more effectively by a physiognomic-ecological classification system, since ecosystems are easily recognizable in the field as well as on satellite images. They argued that the structure and seasonality of the associated vegetation, complemented by ecological data (such as altitude, humidity and drainage) were each determining modifiers that partially distinguished different types of species. This was true not only for plant species, but also for animal, fungal, and bacterial species. The degree of ecosystem distinction is subject to the physiognomic modifiers that can be identified in an image or in the field. If necessary, specific fauna elements can be added, such as the seasonal concentration of animals and the distribution of coral reefs.

Some of the classification systems are as follows:.

• - Physionomic-ecological classification of plant formations on Earth: a system based on the 1974 work of Mueller-Dombois and Heinz Ellenberg,[13]​ and developed by UNESCO. It describes the structure of vegetation and cover above and below ground as observed in the field, described as forms of plant life. This classification is fundamentally a hierarchical vegetation classification system, a physiognomy of independent species that also takes into account ecological factors such as climate, altitude, human influences such as grazing, water regimes, as well as survival strategies such as seasonality. The system was expanded with a basic classification for open water formations.[14]​.

• - Land Cover Classification System (LCCS), developed by the Food and Agriculture Organization (FAO).[15]​.

Various aquatic classification systems are also available. There is an attempt by the United States Geological Survey (USGS) and the Inter-American Biodiversity Information Network (IABIN) to design a comprehensive ecosystem classification system covering both terrestrial and aquatic ecosystems.

From a philosophy of science perspective, ecosystems are not discrete units of nature that can be identified simply by using a correct approach to their classification. According to Tansley's definition ("mental isolations"), any attempt to define or classify ecosystems should be explicit in assigning a classification to the observer/analyst, including its normative basis.

When adding up the structure of an ecosystem, we sometimes talk about the abstract structure in which the parts are the different classes of components, that is, the biotope and the biocenosis, and the different ecological types of organisms (producers, decomposers, predators, etc.). But ecosystems also have a physical structure to the extent that they are never completely homogeneous, but rather have parts, where the conditions are different and more or less uniform, or gradients in some direction.

The ecological environment appears structured by different interfaces or more or less defined limits, called ecotones, and by directional gradients, called ecoclines, of physicochemical factors of the environment. An example is the gradient of humidity, temperature and light intensity within a forest, or the gradient of light, temperature and gas concentrations (for example O) in a lentic ecosystem.

The physical structure of the ecosystem can develop in the vertical and horizontal directions, in both cases we speak of stratification.

• - Vertical structure. A clear and important example is that of lacustrine stratification, where we essentially distinguish epilimnion, mesolimnion (or thermocline) and hypolimnion. The soil profile, with its subdivision into horizons, is another example of stratification with an ecological dimension. The most complex vertical structures occur in forest ecosystems, where we initially distinguish a herbaceous stratum, a shrubby stratum and a tree stratum.

• - Horizontal structure. In some cases a horizontal structure can be recognized, sometimes of a periodic nature. In riparian ecosystems, for example, strips appear parallel to the riverbed, depending above all on the depth of the water table. In periglacial environments, periodic phenomena related to changes in temperature, freezing and thawing, produce regular structures in the substrate "Substrate (ecology)") that also affect the biocenosis. Some ecosystems develop horizontal mosaic structures, as occurs in large areas under two-season tropical climates, where grassy plain and forest or thorny scrub combine, forming a characteristic landscape known as the wooded savanna.

Aquatic ecosystem

Aquatic ecosystems include ocean waters and fresh or salty continental waters.

Each of these bodies of water has particular structures and physical properties in relation to light, temperature, waves, currents and chemical composition, as well as different types of ecological organizations and distribution of organisms.

Oceanography deals with the study of these ecosystems. They can be of two types depending on the sunlight they receive:.

• - Photic: When it receives enough light for photosynthesis, which happens up to 200 m deep. Examples of ecosystems of this type are the beach or coastal ecosystem, the continental shelf, the open sea, coral reef, atoll lagoon, river mouth, etc.[16]​.

• - Aphotic: Where there is not enough light for photosynthesis. As in the shallow sea, deep sea, abyssal, oceanic trench and most of the seabed.

Limnology deals with the study of river and lake ecosystems. This group not only considers running water ecosystems (lotic environments) and still water ecosystems (lentic environments), but also the aqueous habitats of springs, tree holes and even plant cavities where water accumulates and groundwater environments.

Terrestrial ecosystem

They are those in which the flora and fauna develop in the soil or subsoil. They depend on humidity, temperature, altitude and latitude, such that the most biologically rich and diverse ecosystems are found at higher humidity, higher temperature, lower altitude and lower latitude.

Ecosystems can be classified according to the type of vegetation, finding the greatest biodiversity in the forests, and this decreases in the bushes, grasslands, until reaching the desert. Depending on the density of the predominant vegetation, they can be open or closed. Among the main terrestrial ecosystems we have:.

forest ecosystems or forests make up the largest mass of terrestrial biosphere. They can be:

• - Broadleaved forest or broadleaf forests: Made up mostly of angiosperms (flowering trees).

• Jungle: Ecosystems with the highest biological density, highest precipitation and evergreen vegetation. The climate determines various types: Depending on the latitude and temperature it can be a tropical or subtropical forest, depending on the seasonality and humidity it is a rainy or monsoon forest and depending on the altitude it is a montane or basal forest. They are of great complexity, the tree canopy and the understory are considered markedly differentiated ecosystems. The most extensive and diversified forest is the equatorial forest, which is of the tropical-rainy-basal type.

• Dry forest: Tropical and subtropical forests with a long dry season and a short rainy season, so xeric and deciduous vegetation is abundant.

• Temperate hardwood forest: In less humid areas, the Mediterranean forest and the deciduous forest develop; In more humid regions there is the laurel forest or temperate forest.

• - Coniferous forest or needle-leaf forest. Formed mainly by gymnosperms such as conifers.

• Taiga or boreal forest: Forests of greater extent but less biodiversity. It has about 4 months of favorable season. The soil has lichens and moss.

• Temperate coniferous forest: Forests of pine, cedar, fir and redwood, among others, which are among the highest in the world.

• Subtropical coniferous forest: Subhumid forests, mainly pine.

Shrub ecosystems or shrubs are those that have smaller plants such as shrubs and bushes. They can be:

• - Shrubland: Depending on the region and the type of shrubs, it receives various names such as chaparral, Mediterranean scrub, heath, jaral") and fynbos.

• - Xerophilic: The xerophilous scrubland is mainly composed of thorns such as cacti and bromeliads in semi-desert regions.

• - Páramo "Páramo (ecosystem)"): They are mountain scrublands, humid ecosystems of high altitude and equatorial latitude typical of America, Africa and New Guinea.

Herbaceous or herbaceous ecosystems are those with a predominance of herbs (grasses) and are usually found in semi-arid environments with a seasonal climate. They can be:

• - Prairie: A temperate and green climate most of the year due to the predominance of the wet season. They are easily transformed into agricultural land.

• - Steppe: Temperate to cold climate and yellowish in color most of the year due to the predominance of the arid continental climate.

• - Savanna: Tropical and subtropical climate, usually bordering the jungle. Its seasonality leads to the migratory habits of fauna. The absence or irregular presence of shrubs or trees gives rise to the ecosystems of herbaceous savanna, shrub savanna and wooded or wooded savanna.

• - Alpine meadow: Also called mountain meadow, alpine tundra or mountain grassland. They are high altitude ecosystems. In the Andes (puna region) the pajonales stand out. It is also found in the Alps, Tibet and others.

The tundra is made up of mosses, lichens, grasses and small shrubs, so it is actually a humid ecosystem defined by the absence of trees and which has a frozen subsoil. They are found between the taiga and the perpetual snow. The Arctic tundra is large, in Antarctica they are small areas and the alpine tundra is better defined as mountain meadow.

• - Desert itself: They have very scarce flora and fauna. They are typical of subtropical climates, although they can also be found in tropical, temperate, cold and mountain areas.

• - Indlandsis: It is the ice cap or polar desert. The ecosystem has more development on the coasts or edges of the ice.

It is the non-natural ecosystem with control or intervention of human beings.

• - Urban environment.

• - Rural means of exploitation such as crop fields, breeding, mines, logging, etc.

• - Artificial and semi-natural ecosystems: Such as the creation of forests, ponds, introduction of new species, abandonment of crop fields, desertification, etc.

It is the floodable or wetland ecosystem such as the swamp or swamp, which is considered, depending on the case, a terrestrial or aquatic ecosystem, or more closely, a hybrid between them. They are soils covered with fresh or salt water, permanently or for much of the year, commonly found in alluvial plains. Depending on their characteristics, they present aquatic plants, herbaceous plants, trees, ferns, algae and fauna adapted to this habitat. Some ecosystems of this type:

• - Flooded savannah: Alluvial plain of savanna. The Pantanal in central South America stands out as the largest wetland in the world, an ecosystem of great biodiversity.

• - Flooded jungle: Jungle alluvial plain such as the várzea and agapós of Brazil, or the aguajales and shoals of Peru.

• - Coniferous swamp"): Formed in plains populated with trees and bushes.

• - Mangrove: Tropical coastal mangrove ecosystem.

• - Marsh: Herbaceous wetland near the sea.

• - Reedbed: Riverside ecosystem of reeds next to lakes or rivers.

• - Estuary: Swamp formed near rivers or lakes, formed by aquatic plants or palm trees and various vegetation.

• - Peat bog: Wetland formed by peat in tundras and taigas, composed of mosses and accumulation of dead plant matter.

• - Bofedal: High mountain herbaceous wetland.

Within microbiology, systems composed of interdependent microbial organisms that share the same habitat can also be described. Among them stand out:

• - microbiotas: which are made up of a set of microorganisms that are normally located in different places in the body of multicellular living beings, such as humans.

• - biofilms or biofilms: which are organized microbial ecosystems, made up of one or several microorganisms associated with a living or inert surface, which have functional characteristics and complex structures.

• - kefir granules: made up of a symbiotic biotic mass in which different species of probiotic bacteria and yeast coexist, wrapped in a polysaccharide matrix, called kefiran.

From the human point of view, many see ecosystems as production units similar to those that produce goods and services. Among the most common goods produced by ecosystems are wood and forage for livestock. Bush meat can be very profitable under a well-controlled management system as occurs in some places in Southern Africa and Kenya. There has been less success in the discovery and production of pharmaceutical substances from wild organisms.

Services derived from ecosystems include:

• - The enjoyment of nature: which provides sources of income and employment in the tourism sector, often referred to as ecotourism.

• - Water retention: facilitates better water distribution.

• - Soil protection: an open-air laboratory for scientific research, etc.

A greater number of species or biological diversity (biodiversity) of an ecosystem gives it greater capacity for recovery because having a greater number of species can absorb and reduce the effects of environmental changes. This reduces the impact of environmental change on the overall structure of the ecosystem and reduces the chances of a change to a different state. This is not universal; There is no proven relationship between species diversity and the capacity of an ecosystem to provide goods and services in a sustainable manner.

Tropical rainforests produce very few direct goods and services and are extremely vulnerable to change. In contrast, temperate forests regenerate rapidly and return to their previous state of development within a human generation, as can be seen after forest fires. Some grasslands have been sustainably exploited for thousands of years: (Mongolia, Africa, European heathlands).

The introduction of new elements, whether abiotic or biotic, can have disruptive effects. In some cases it can lead to the collapse and death of many species within the ecosystem.

However, in some cases ecosystems have the capacity to recover. The difference between a collapse and a slow recovery depends on two factors: the toxicity of the introduced element and the recovery capacity of the original ecosystem.

Ecosystems are governed primarily by stochastic (chance) events, the reactions these events cause in inert materials, and the responses of organisms to the conditions around them. Thus, an ecosystem is the result of the sum of the individual responses of organisms to stimuli received from elements in the environment. The presence or absence of populations simply depends on reproductive and dispersal success; Population levels fluctuate in response to stochastic events. If the number of species in an ecosystem is higher, the number of stimuli is also higher. Since the beginning of life, organisms have survived continuous changes through natural selection. Thanks to natural selection, the planet's species have continually adapted to changes through variations in their biological composition and distribution.

It can be shown mathematically that larger numbers of different interacting factors tend to dampen fluctuations in each of the individual factors. Given the great diversity of organisms on Earth, most ecosystems change very gradually and as some species disappear, others emerge or enter. Locally, subpopulations continually become extinct and are later replaced by the dispersion of other subpopulations.[17]​.

If ecosystems are governed mainly by stochastic processes, they must be more resistant to abrupt changes than each species in particular. In the absence of balance in nature, the species composition of an ecosystem may undergo modifications depending on the nature of the change, but complete ecological collapse may be rare.

• - Ehrlich, Paul; Walker, Brian "Rivets and Redundancy." BioScience, vol.48 no. 5. May 1998. pp. 387. American Institute of Biological Sciences.

• - Wiktionary has definitions and other information about ecosystem.

• - This work contains a translation derived from "Ecosystem" from English Wikipedia, published by its editors under the GNU Free Documentation License and the Creative Commons Attribution-ShareAlike 4.0 International License.

A biome is a global classification of similar areas, including many climatically and geographically similar ecosystems, that is, an ecologically defined area in which similar climatic conditions occur and similar communities of plants, animals and soil organisms are often referred to as large-scale ecosystems. Biomes are defined based on factors such as plant structures (trees, shrubs, and grasses), leaf types (broadleaf and needle plants), distance between plants (forest, jungle, savanna), and climate. Unlike ecozones, biomes are not defined by genetics, taxonomy, or historical similarities and are frequently identified with special patterns of ecological succession and climax vegetation.

The simplest classification of biomes is:.

• - Terrestrial biomes.

• - Freshwater biomes.

• - Marine biomes.

Ecosystems have acquired, politically, special relevance since the Convention on Biological Diversity (CBD) (or in English "Convention on Biological Diversity")[10]​—ratified by more than 175 countries in Rio de Janeiro in June 1992—establishes "the protection of ecosystems, natural habitats and the maintenance of viable populations of species in natural environments"[11]​ as a commitment of the ratifying countries. This has created a political need to spatially identify ecosystems and somehow distinguish between them. The CBD defines an "ecosystem" as "a dynamic complex of plant, animal and microorganism communities and their non-living environment that interact as a functional unit."[12]​.

With the need to protect ecosystems comes the political need to describe and identify them efficiently. Vreugdenhil et al. They argued that this could be achieved more effectively by a physiognomic-ecological classification system, since ecosystems are easily recognizable in the field as well as on satellite images. They argued that the structure and seasonality of the associated vegetation, complemented by ecological data (such as altitude, humidity and drainage) were each determining modifiers that partially distinguished different types of species. This was true not only for plant species, but also for animal, fungal, and bacterial species. The degree of ecosystem distinction is subject to the physiognomic modifiers that can be identified in an image or in the field. If necessary, specific fauna elements can be added, such as the seasonal concentration of animals and the distribution of coral reefs.

Some of the classification systems are as follows:.

• - Physionomic-ecological classification of plant formations on Earth: a system based on the 1974 work of Mueller-Dombois and Heinz Ellenberg,[13]​ and developed by UNESCO. It describes the structure of vegetation and cover above and below ground as observed in the field, described as forms of plant life. This classification is fundamentally a hierarchical vegetation classification system, a physiognomy of independent species that also takes into account ecological factors such as climate, altitude, human influences such as grazing, water regimes, as well as survival strategies such as seasonality. The system was expanded with a basic classification for open water formations.[14]​.

• - Land Cover Classification System (LCCS), developed by the Food and Agriculture Organization (FAO).[15]​.

Various aquatic classification systems are also available. There is an attempt by the United States Geological Survey (USGS) and the Inter-American Biodiversity Information Network (IABIN) to design a comprehensive ecosystem classification system covering both terrestrial and aquatic ecosystems.

From a philosophy of science perspective, ecosystems are not discrete units of nature that can be identified simply by using a correct approach to their classification. According to Tansley's definition ("mental isolations"), any attempt to define or classify ecosystems should be explicit in assigning a classification to the observer/analyst, including its normative basis.

When adding up the structure of an ecosystem, we sometimes talk about the abstract structure in which the parts are the different classes of components, that is, the biotope and the biocenosis, and the different ecological types of organisms (producers, decomposers, predators, etc.). But ecosystems also have a physical structure to the extent that they are never completely homogeneous, but rather have parts, where the conditions are different and more or less uniform, or gradients in some direction.

The ecological environment appears structured by different interfaces or more or less defined limits, called ecotones, and by directional gradients, called ecoclines, of physicochemical factors of the environment. An example is the gradient of humidity, temperature and light intensity within a forest, or the gradient of light, temperature and gas concentrations (for example O) in a lentic ecosystem.

The physical structure of the ecosystem can develop in the vertical and horizontal directions, in both cases we speak of stratification.

• - Vertical structure. A clear and important example is that of lacustrine stratification, where we essentially distinguish epilimnion, mesolimnion (or thermocline) and hypolimnion. The soil profile, with its subdivision into horizons, is another example of stratification with an ecological dimension. The most complex vertical structures occur in forest ecosystems, where we initially distinguish a herbaceous stratum, a shrubby stratum and a tree stratum.

• - Horizontal structure. In some cases a horizontal structure can be recognized, sometimes of a periodic nature. In riparian ecosystems, for example, strips appear parallel to the riverbed, depending above all on the depth of the water table. In periglacial environments, periodic phenomena related to changes in temperature, freezing and thawing, produce regular structures in the substrate "Substrate (ecology)") that also affect the biocenosis. Some ecosystems develop horizontal mosaic structures, as occurs in large areas under two-season tropical climates, where grassy plain and forest or thorny scrub combine, forming a characteristic landscape known as the wooded savanna.

Aquatic ecosystem

Aquatic ecosystems include ocean waters and fresh or salty continental waters.

Each of these bodies of water has particular structures and physical properties in relation to light, temperature, waves, currents and chemical composition, as well as different types of ecological organizations and distribution of organisms.

Oceanography deals with the study of these ecosystems. They can be of two types depending on the sunlight they receive:.

• - Photic: When it receives enough light for photosynthesis, which happens up to 200 m deep. Examples of ecosystems of this type are the beach or coastal ecosystem, the continental shelf, the open sea, coral reef, atoll lagoon, river mouth, etc.[16]​.

• - Aphotic: Where there is not enough light for photosynthesis. As in the shallow sea, deep sea, abyssal, oceanic trench and most of the seabed.

Limnology deals with the study of river and lake ecosystems. This group not only considers running water ecosystems (lotic environments) and still water ecosystems (lentic environments), but also the aqueous habitats of springs, tree holes and even plant cavities where water accumulates and groundwater environments.

Terrestrial ecosystem

They are those in which the flora and fauna develop in the soil or subsoil. They depend on humidity, temperature, altitude and latitude, such that the most biologically rich and diverse ecosystems are found at higher humidity, higher temperature, lower altitude and lower latitude.

Ecosystems can be classified according to the type of vegetation, finding the greatest biodiversity in the forests, and this decreases in the bushes, grasslands, until reaching the desert. Depending on the density of the predominant vegetation, they can be open or closed. Among the main terrestrial ecosystems we have:.

forest ecosystems or forests make up the largest mass of terrestrial biosphere. They can be:

• - Broadleaved forest or broadleaf forests: Made up mostly of angiosperms (flowering trees).

• Jungle: Ecosystems with the highest biological density, highest precipitation and evergreen vegetation. The climate determines various types: Depending on the latitude and temperature it can be a tropical or subtropical forest, depending on the seasonality and humidity it is a rainy or monsoon forest and depending on the altitude it is a montane or basal forest. They are of great complexity, the tree canopy and the understory are considered markedly differentiated ecosystems. The most extensive and diversified forest is the equatorial forest, which is of the tropical-rainy-basal type.

• Dry forest: Tropical and subtropical forests with a long dry season and a short rainy season, so xeric and deciduous vegetation is abundant.

• Temperate hardwood forest: In less humid areas, the Mediterranean forest and the deciduous forest develop; In more humid regions there is the laurel forest or temperate forest.

• - Coniferous forest or needle-leaf forest. Formed mainly by gymnosperms such as conifers.

• Taiga or boreal forest: Forests of greater extent but less biodiversity. It has about 4 months of favorable season. The soil has lichens and moss.

• Temperate coniferous forest: Forests of pine, cedar, fir and redwood, among others, which are among the highest in the world.

• Subtropical coniferous forest: Subhumid forests, mainly pine.

Shrub ecosystems or shrubs are those that have smaller plants such as shrubs and bushes. They can be:

• - Shrubland: Depending on the region and the type of shrubs, it receives various names such as chaparral, Mediterranean scrub, heath, jaral") and fynbos.

• - Xerophilic: The xerophilous scrubland is mainly composed of thorns such as cacti and bromeliads in semi-desert regions.

• - Páramo "Páramo (ecosystem)"): They are mountain scrublands, humid ecosystems of high altitude and equatorial latitude typical of America, Africa and New Guinea.

Herbaceous or herbaceous ecosystems are those with a predominance of herbs (grasses) and are usually found in semi-arid environments with a seasonal climate. They can be:

• - Prairie: A temperate and green climate most of the year due to the predominance of the wet season. They are easily transformed into agricultural land.

• - Steppe: Temperate to cold climate and yellowish in color most of the year due to the predominance of the arid continental climate.

• - Savanna: Tropical and subtropical climate, usually bordering the jungle. Its seasonality leads to the migratory habits of fauna. The absence or irregular presence of shrubs or trees gives rise to the ecosystems of herbaceous savanna, shrub savanna and wooded or wooded savanna.

• - Alpine meadow: Also called mountain meadow, alpine tundra or mountain grassland. They are high altitude ecosystems. In the Andes (puna region) the pajonales stand out. It is also found in the Alps, Tibet and others.

The tundra is made up of mosses, lichens, grasses and small shrubs, so it is actually a humid ecosystem defined by the absence of trees and which has a frozen subsoil. They are found between the taiga and the perpetual snow. The Arctic tundra is large, in Antarctica they are small areas and the alpine tundra is better defined as mountain meadow.

• - Desert itself: They have very scarce flora and fauna. They are typical of subtropical climates, although they can also be found in tropical, temperate, cold and mountain areas.

• - Indlandsis: It is the ice cap or polar desert. The ecosystem has more development on the coasts or edges of the ice.

It is the non-natural ecosystem with control or intervention of human beings.

• - Urban environment.

• - Rural means of exploitation such as crop fields, breeding, mines, logging, etc.

• - Artificial and semi-natural ecosystems: Such as the creation of forests, ponds, introduction of new species, abandonment of crop fields, desertification, etc.

It is the floodable or wetland ecosystem such as the swamp or swamp, which is considered, depending on the case, a terrestrial or aquatic ecosystem, or more closely, a hybrid between them. They are soils covered with fresh or salt water, permanently or for much of the year, commonly found in alluvial plains. Depending on their characteristics, they present aquatic plants, herbaceous plants, trees, ferns, algae and fauna adapted to this habitat. Some ecosystems of this type:

• - Flooded savannah: Alluvial plain of savanna. The Pantanal in central South America stands out as the largest wetland in the world, an ecosystem of great biodiversity.

• - Flooded jungle: Jungle alluvial plain such as the várzea and agapós of Brazil, or the aguajales and shoals of Peru.

• - Coniferous swamp"): Formed in plains populated with trees and bushes.

• - Mangrove: Tropical coastal mangrove ecosystem.

• - Marsh: Herbaceous wetland near the sea.

• - Reedbed: Riverside ecosystem of reeds next to lakes or rivers.

• - Estuary: Swamp formed near rivers or lakes, formed by aquatic plants or palm trees and various vegetation.

• - Peat bog: Wetland formed by peat in tundras and taigas, composed of mosses and accumulation of dead plant matter.

• - Bofedal: High mountain herbaceous wetland.

Within microbiology, systems composed of interdependent microbial organisms that share the same habitat can also be described. Among them stand out:

• - microbiotas: which are made up of a set of microorganisms that are normally located in different places in the body of multicellular living beings, such as humans.

• - biofilms or biofilms: which are organized microbial ecosystems, made up of one or several microorganisms associated with a living or inert surface, which have functional characteristics and complex structures.

• - kefir granules: made up of a symbiotic biotic mass in which different species of probiotic bacteria and yeast coexist, wrapped in a polysaccharide matrix, called kefiran.

From the human point of view, many see ecosystems as production units similar to those that produce goods and services. Among the most common goods produced by ecosystems are wood and forage for livestock. Bush meat can be very profitable under a well-controlled management system as occurs in some places in Southern Africa and Kenya. There has been less success in the discovery and production of pharmaceutical substances from wild organisms.

Services derived from ecosystems include:

• - The enjoyment of nature: which provides sources of income and employment in the tourism sector, often referred to as ecotourism.

• - Water retention: facilitates better water distribution.

• - Soil protection: an open-air laboratory for scientific research, etc.

A greater number of species or biological diversity (biodiversity) of an ecosystem gives it greater capacity for recovery because having a greater number of species can absorb and reduce the effects of environmental changes. This reduces the impact of environmental change on the overall structure of the ecosystem and reduces the chances of a change to a different state. This is not universal; There is no proven relationship between species diversity and the capacity of an ecosystem to provide goods and services in a sustainable manner.

Tropical rainforests produce very few direct goods and services and are extremely vulnerable to change. In contrast, temperate forests regenerate rapidly and return to their previous state of development within a human generation, as can be seen after forest fires. Some grasslands have been sustainably exploited for thousands of years: (Mongolia, Africa, European heathlands).

The introduction of new elements, whether abiotic or biotic, can have disruptive effects. In some cases it can lead to the collapse and death of many species within the ecosystem.

However, in some cases ecosystems have the capacity to recover. The difference between a collapse and a slow recovery depends on two factors: the toxicity of the introduced element and the recovery capacity of the original ecosystem.

Ecosystems are governed primarily by stochastic (chance) events, the reactions these events cause in inert materials, and the responses of organisms to the conditions around them. Thus, an ecosystem is the result of the sum of the individual responses of organisms to stimuli received from elements in the environment. The presence or absence of populations simply depends on reproductive and dispersal success; Population levels fluctuate in response to stochastic events. If the number of species in an ecosystem is higher, the number of stimuli is also higher. Since the beginning of life, organisms have survived continuous changes through natural selection. Thanks to natural selection, the planet's species have continually adapted to changes through variations in their biological composition and distribution.

It can be shown mathematically that larger numbers of different interacting factors tend to dampen fluctuations in each of the individual factors. Given the great diversity of organisms on Earth, most ecosystems change very gradually and as some species disappear, others emerge or enter. Locally, subpopulations continually become extinct and are later replaced by the dispersion of other subpopulations.[17]​.

If ecosystems are governed mainly by stochastic processes, they must be more resistant to abrupt changes than each species in particular. In the absence of balance in nature, the species composition of an ecosystem may undergo modifications depending on the nature of the change, but complete ecological collapse may be rare.

• - Ehrlich, Paul; Walker, Brian "Rivets and Redundancy." BioScience, vol.48 no. 5. May 1998. pp. 387. American Institute of Biological Sciences.

• - Wiktionary has definitions and other information about ecosystem.

• - This work contains a translation derived from "Ecosystem" from English Wikipedia, published by its editors under the GNU Free Documentation License and the Creative Commons Attribution-ShareAlike 4.0 International License.