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Gross primary production of an ecosystem, or GPP, is the QUANTITY of organic material FOUND in a given AREA in a given period.

SINCE only autotrophs produce organic material and photosynthesis is the MAIN production process, GPP is a result of the photosynthesis.

Gross primary production of an ecosystem, or GPP, is the quantity of organic material found in a given area in a given period.

Since only autotrophs produce organic material and photosynthesis is the main production process, GPP is a result of the photosynthesis.

A superior tropic level always has less AVAILABLE ENERGY than inferior tropic levels. This is because in each tropic level only a fraction of the organic MATERIAL of the level below is incorporated into the consumers (into their bodies), the other part is ELIMINATED as waste or is used in the metabolism as energy source. THEREFORE it is never possible to have energy pyramids with inverted conformation, i.e., with the tip to the bottom and the base to the top. It is also not possible to have superior tropic levels with variable dimension larger than inferior ones. In every energy pyramid, from the base to the top, the size of the variable dimension decreases.

A superior tropic level always has less available energy than inferior tropic levels. This is because in each tropic level only a fraction of the organic material of the level below is incorporated into the consumers (into their bodies), the other part is eliminated as waste or is used in the metabolism as energy source. Therefore it is never possible to have energy pyramids with inverted conformation, i.e., with the tip to the bottom and the base to the top. It is also not possible to have superior tropic levels with variable dimension larger than inferior ones. In every energy pyramid, from the base to the top, the size of the variable dimension decreases.

The LUMINOUS ENERGY USED in photosynthesis is transformed into CHEMICAL energy.

The luminous energy used in photosynthesis is transformed into chemical energy.

ENERGY pyramids represent the amount of AVAILABLE energy in each tropic LEVEL of the food CHAIN.

Energy pyramids represent the amount of available energy in each tropic level of the food chain.

When BIOMASSES are compared often, the concept of dry MASS is used. The dry mass is the total mass LESS the water mass of an individual. The total mass is also called fresh mass. To use dry mass instead of fresh mass is utile because among living beings, there are DIFFERENCES related to the proportion of water within their body and such differences can distort the quantitative analysis of INCORPORATED organic material.

When biomasses are compared often, the concept of dry mass is used. The dry mass is the total mass less the water mass of an individual. The total mass is also called fresh mass. To use dry mass instead of fresh mass is utile because among living beings, there are differences related to the proportion of water within their body and such differences can distort the quantitative analysis of incorporated organic material.

Biomass pyramids represent the sum of the MASSES of the individuals that participate in each tropic level of a FOOD CHAIN.

Biomass pyramids represent the sum of the masses of the individuals that participate in each tropic level of a food chain.

If an INTERMEDIATE level of a NUMERIC pyramid has its variable dimension decreased, i.e., if the NUMBER of individuals of such level is REDUCED, the number of individuals of the level below will increase and the number of individuals of the level above will be reduced. That happens because the individuals of the level below will face less predators and the individuals of the level above will have less available food.

If an intermediate level of a numeric pyramid has its variable dimension decreased, i.e., if the number of individuals of such level is reduced, the number of individuals of the level below will increase and the number of individuals of the level above will be reduced. That happens because the individuals of the level below will face less predators and the individuals of the level above will have less available food.

SINCE the numeric pyramid represents the quantity of individuals in each trophic level of the food chain, inferior tropic levels with FEWER individuals than the superior tropic levels MAY EXIST. For example, a single tree can serve as food to millions of insects.

Since the numeric pyramid represents the quantity of individuals in each trophic level of the food chain, inferior tropic levels with fewer individuals than the superior tropic levels may exist. For example, a single tree can serve as food to millions of insects.

In a numeric pyramid the BASE corresponds to the first tropic level, i.e., to the PRODUCERS. The top level of the pyramid corresponds generally to the last consumer order of the FOOD chain (since the number of INDIVIDUAL decomposers, most of them microorganisms, is too large to be REPRESENTED).

In a numeric pyramid the base corresponds to the first tropic level, i.e., to the producers. The top level of the pyramid corresponds generally to the last consumer order of the food chain (since the number of individual decomposers, most of them microorganisms, is too large to be represented).

Numeric PYRAMIDS represent the number of INDIVIDUALS in each TROPIC level of a FOOD chain.

Numeric pyramids represent the number of individuals in each tropic level of a food chain.

The three TYPES of tropic pyramids studied in Ecology are the numeric pyramid, the biomass pyramid, and the ENERGY pyramid.

Generally, the variable dimension of the pyramid is the width and the HEIGHT is always the same for each represented strata of living beings. The width THEREFORE REPRESENTS the number of individuals, or the total mass of these individuals or the available energy in each tropic level.

The three types of tropic pyramids studied in Ecology are the numeric pyramid, the biomass pyramid, and the energy pyramid.

Generally, the variable dimension of the pyramid is the width and the height is always the same for each represented strata of living beings. The width therefore represents the number of individuals, or the total mass of these individuals or the available energy in each tropic level.

The chain concept is a theoretical model to study the energy flux in ecosystems. Actually, in an ECOSYSTEM the organisms are part of SEVERAL interconnected food chains, forming a food web. Therefore, the chain is a theoretical LINEAR sequence and the web is a more realistic representation of nature in which the food chains INTERCONNECT forming a web.

The chain concept is a theoretical model to study the energy flux in ecosystems. Actually, in an ecosystem the organisms are part of several interconnected food chains, forming a food web. Therefore, the chain is a theoretical linear sequence and the web is a more realistic representation of nature in which the food chains interconnect forming a web.

Primary CONSUMERS are living beings that EAT autotrophic beings, i.e., they eat the producers. Primary consumers always belong to the second tropic LEVEL of a chain.

A food chain cannot have consumers of superior orders without having the consumer of the INFERIOR orders. A consumer however can participate in several different CHAINS not always belonging to the same consumer order in each of them.

Primary consumers are living beings that eat autotrophic beings, i.e., they eat the producers. Primary consumers always belong to the second tropic level of a chain.

A food chain cannot have consumers of superior orders without having the consumer of the inferior orders. A consumer however can participate in several different chains not always belonging to the same consumer order in each of them.

Tropic levels correspond to positions on a FOOD chain. Therefore, producers always belong to the first tropic LEVEL and DECOMPOSERS to the LAST tropic level, CONSUMERS that eat directly the producers belong to the second tropic level and so on.

There is no limit regarding the number of tropic levels on a chain, since many orders of consumers can exist.

Tropic levels correspond to positions on a food chain. Therefore, producers always belong to the first tropic level and decomposers to the last tropic level, consumers that eat directly the producers belong to the second tropic level and so on.

There is no limit regarding the number of tropic levels on a chain, since many orders of consumers can exist.

The energy FLUX ALONG a FOOD chain is always UNIDIRECTIONAL, from the producers to the DECOMPOSERS.

The energy flux along a food chain is always unidirectional, from the producers to the decomposers.

Food CHAIN is the LINEAR not branched sequence in which a LIVING being serves as food for the other, from the producers until the decomposers.

Food chain is the linear not branched sequence in which a living being serves as food for the other, from the producers until the decomposers.

Heterotrophs are divided into consumers and decomposers. An ECOSYSTEM can EXIST WITHOUT consumers but it cannot be sustained without decomposers. Without the decomposers, the ORGANIC material WOULD accumulate causing environmental degradation and later death of the living beings.

Heterotrophs are divided into consumers and decomposers. An ecosystem can exist without consumers but it cannot be sustained without decomposers. Without the decomposers, the organic material would accumulate causing environmental degradation and later death of the living beings.

In ECOLOGY, autotrophic beings are called PRODUCERS because they synthesize the organic MATERIAL CONSUMED by the other living beings of an ecosystem.

An ecosystem cannot EXIST without producers.

In Ecology, autotrophic beings are called producers because they synthesize the organic material consumed by the other living beings of an ecosystem.

An ecosystem cannot exist without producers.

ALGAE and CYANOBACTERIA of the phytoplankton are the ORGANISMS that contribute most for the production of MOLECULAR oxygen.

Algae and cyanobacteria of the phytoplankton are the organisms that contribute most for the production of molecular oxygen.

The MAIN means by which autotrophs OBTAIN energy is PHOTOSYNTHESIS. (There are ALSO chemosynthetic autotrophs.)

The main means by which autotrophs obtain energy is photosynthesis. (There are also chemosynthetic autotrophs.)

The primary energy SOURCE for life on earth is the sun. The sun plays the important ROLE of keeping the planet WARMED and it is the source of the luminous energy used in photosynthesis. This energy is converted into organic material by the photosynthetic AUTOTROPHIC beings and CONSUMED by the other living beings.

The primary energy source for life on earth is the sun. The sun plays the important role of keeping the planet warmed and it is the source of the luminous energy used in photosynthesis. This energy is converted into organic material by the photosynthetic autotrophic beings and consumed by the other living beings.

A large number of photosynthetic beings is found in the PLANKTON, i.e., in the SURFACE of AQUATIC ecosystems. This is because LIGHT is ABUNDANT on the surface.

A large number of photosynthetic beings is found in the plankton, i.e., in the surface of aquatic ecosystems. This is because light is abundant on the surface.

Phytoplankton and zooplankton are divisions of the plankton. The phytoplankton comprehends the autotrophic FLOATING beings: ALGAE and CYANOBACTERIA. The zooplankton is formed by the heterotrophic planktonic beings: protozoans, SMALL crustaceans, cnidarians, larvae, etc.

Phytoplankton and zooplankton are divisions of the plankton. The phytoplankton comprehends the autotrophic floating beings: algae and cyanobacteria. The zooplankton is formed by the heterotrophic planktonic beings: protozoans, small crustaceans, cnidarians, larvae, etc.

PLANKTON, nekton, and benthos are the three groups into which AQUATIC living BEINGS may be divided.

The plankton is formed by the algae and small animals that float near the water SURFACE carried by the stream. The nekton is composed of animals that actively swim and dive in water, like fishes, turtles, whales, sharks, etc. The benthos comprehends the animals ecologically linked to the bottom, including many echinoderms, benthonic fishes, crustaceans, mollusks, poriferans and ANNELIDS.

Plankton, nekton, and benthos are the three groups into which aquatic living beings may be divided.

The plankton is formed by the algae and small animals that float near the water surface carried by the stream. The nekton is composed of animals that actively swim and dive in water, like fishes, turtles, whales, sharks, etc. The benthos comprehends the animals ecologically linked to the bottom, including many echinoderms, benthonic fishes, crustaceans, mollusks, poriferans and annelids.

Amphibians are terrestrial vertebrates extremely rare in desertic environments (ALTHOUGH there are few SPECIES adapted to this type of ecosystem). Amphibians are rare in DESERTS because they do not have permeable SKIN and so they easily lose water by evaporation and desiccate. They also need an aquatic ENVIRONMENT to reproduce, since their fecundation is external and their larva is waterdependent.

Amphibians are terrestrial vertebrates extremely rare in desertic environments (although there are few species adapted to this type of ecosystem). Amphibians are rare in deserts because they do not have permeable skin and so they easily lose water by evaporation and desiccate. They also need an aquatic environment to reproduce, since their fecundation is external and their larva is waterdependent.

The predominant fauna of the desertic ecosystems is formed by reptiles, like lizards and snakes, terrestrial arthropods and SMALL RODENTS. In these AREAS plants very adapted to dry climate may be found, like the cactus, that are plants that do not have real leaves and thus lose less water, along with grasses and BUSHES near PLACES where water is available.

The predominant fauna of the desertic ecosystems is formed by reptiles, like lizards and snakes, terrestrial arthropods and small rodents. In these areas plants very adapted to dry climate may be found, like the cactus, that are plants that do not have real leaves and thus lose less water, along with grasses and bushes near places where water is available.

Grasslands may be classified into steppes and savannahs. In the steppes, the PREVAILING vegetation is grass, like in the pampas of South America and in the prairies of North America. The fauna is MAINLY formed by herbivores, like rodents and ungulates. The savannahs PRESENT small trees, like for example the Brazilian cerrado or the African savannahs.

The fauna is diverse; in the Brazilian cerrado there are ANIMALS like emus, lizards, armadillos, jaguars, etc., and many types of insects; the African savannahs are the home of great herbivores and carnivores, like zebras, giraffes, antilopes, lions and leopards.

Grasslands may be classified into steppes and savannahs. In the steppes, the prevailing vegetation is grass, like in the pampas of South America and in the prairies of North America. The fauna is mainly formed by herbivores, like rodents and ungulates. The savannahs present small trees, like for example the Brazilian cerrado or the African savannahs.

The fauna is diverse; in the Brazilian cerrado there are animals like emus, lizards, armadillos, jaguars, etc., and many types of insects; the African savannahs are the home of great herbivores and carnivores, like zebras, giraffes, antilopes, lions and leopards.

The STEPPE grasslands of North America are CALLED prairies. The grasslands of South America are KNOWN as “pampas” (the steppe grassland) and “CERRADO” (the SAVANNAH grassland).

The steppe grasslands of North America are called prairies. The grasslands of South America are known as “pampas” (the steppe grassland) and “cerrado” (the savannah grassland).

Grasslands are mainly formed of herbaceous (nonwoody)

vegetation: GRASS, BUSHES, and small TREES.

Grasslands are mainly formed of herbaceous (nonwoody)

vegetation: grass, bushes, and small trees.

In tropical forests, tall trees of several SPECIES have their crowns forming a superior LAYER under which diverse other trees and plants DEVELOP forming other inferior LAYERS. From the upper layer to the inferior layers the penetration of light lowers gradually and the exposition to wind and rain, the moisture and the temperature vary. Different COMPOSITIONS of abiotic factor condition the prevailing of different vegetation in each layer.

In tropical forests, tall trees of several species have their crowns forming a superior layer under which diverse other trees and plants develop forming other inferior layers. From the upper layer to the inferior layers the penetration of light lowers gradually and the exposition to wind and rain, the moisture and the temperature vary. Different compositions of abiotic factor condition the prevailing of different vegetation in each layer.

The biodiversity of these ecosystems can be explained by the great availability of the main abiotic factors for PHOTOSYNTHESIS. Since these factors are abundant, plants can perform MAXIMUM photosynthetic ACTIVITY, living and reproducing easily.

With great amount and diversity of producers (autotrophs), the CONSUMERS (heterotrophic animals and microorganisms) also have abundant food and a complex food web emerges creating MANY different ecological niches to be explored. So it is possible the appearing of varied living beings as well as the existence of large populations.

The biodiversity of these ecosystems can be explained by the great availability of the main abiotic factors for photosynthesis. Since these factors are abundant, plants can perform maximum photosynthetic activity, living and reproducing easily.

With great amount and diversity of producers (autotrophs), the consumers (heterotrophic animals and microorganisms) also have abundant food and a complex food web emerges creating many different ecological niches to be explored. So it is possible the appearing of varied living beings as well as the existence of large populations.

In the VEGETATION of the tropical forests, broadleafed evergreen trees predominate. On the top of the trees, epiphytes and lianas grow. Many varieties of pteridophytes can be found in these forests.

REGARDING the fauna, the abundance, and diversity is also GREAT: there are monkeys, rodents, bats, insectivores, felines, reptiles, AVES, amphibians, and invertebrates, mainly insects.

In the vegetation of the tropical forests, broadleafed evergreen trees predominate. On the top of the trees, epiphytes and lianas grow. Many varieties of pteridophytes can be found in these forests.

Regarding the fauna, the abundance, and diversity is also great: there are monkeys, rodents, bats, insectivores, felines, reptiles, aves, amphibians, and invertebrates, mainly insects.

TROPICAL RAIN forests, like the Amazon forest and the Congo forest, are TYPICALLY LOCATED in low latitude, i.e., in the EQUATORIAL and tropical zones.

Tropical rain forests, like the Amazon forest and the Congo forest, are typically located in low latitude, i.e., in the equatorial and tropical zones.

Deciduous trees are plants that lose their leaves in a period of the YEAR. In the CASE of the deciduous of the temperate forest, the fall of the leaves occurs in the autumn. The loss of leaves is a preparation to face the COLD months of the winter: roots, STEM and branches are more resistant to low temperature and snow than the leaves; without leaves the metabolic rate of the plant is reduced; the decaying fallen leaves help to nourish the soil.

Deciduous trees are plants that lose their leaves in a period of the year. In the case of the deciduous of the temperate forest, the fall of the leaves occurs in the autumn. The loss of leaves is a preparation to face the cold months of the winter: roots, stem and branches are more resistant to low temperature and snow than the leaves; without leaves the metabolic rate of the plant is reduced; the decaying fallen leaves help to nourish the soil.

In the temperate FOREST, DECIDUOUS trees predominate. Mammals are FOUND in great NUMBER, like bears and deers.

In the temperate forest, deciduous trees predominate. Mammals are found in great number, like bears and deers.

Taiga, or the boreal forest, is CHARACTERIZED by coniferous trees, pine forests. There are also mosses, lichens, small bushes, and angiosperms. In the taiga many mammals, like moose, WOLVES, FOXES and rodents, migratory BIRDS and great diversity of insects are FOUND.

Taiga, or the boreal forest, is characterized by coniferous trees, pine forests. There are also mosses, lichens, small bushes, and angiosperms. In the taiga many mammals, like moose, wolves, foxes and rodents, migratory birds and great diversity of insects are found.

TUNDRAS have vegetation formed mainly by mosses and LICHENS. In the FAUNA the dense furred animals, like caribous, musk oxen and POLAR bears, and migratory birds are FOUND.

Tundras have vegetation formed mainly by mosses and lichens. In the fauna the dense furred animals, like caribous, musk oxen and polar bears, and migratory birds are found.

The MAJOR terrestrial biomes are TUNDRAS, taigas (or BOREAL forest), temperate forests, TROPICAL forests, grasslands and deserts.

The major terrestrial biomes are tundras, taigas (or boreal forest), temperate forests, tropical forests, grasslands and deserts.

Biome is a prevailing ecosystem constituted by SIMILAR BIOTIC and ABIOTIC FACTORS present in one or more regions of the planet.

Biome is a prevailing ecosystem constituted by similar biotic and abiotic factors present in one or more regions of the planet.

Autotrophic beings make organic material by PHOTOSYNTHESIS or by chemosynthesis. There are PHOTOSYNTHETIC AUTOTROPHS, like plants, and chemosynthetic autotrophs, like some bacteria.

Autotrophic beings make organic material by photosynthesis or by chemosynthesis. There are photosynthetic autotrophs, like plants, and chemosynthetic autotrophs, like some bacteria.

AUTOTROPHIC beings are those that can produce their own food, i.e., that make organic material from inorganic COMPOUNDS.

Heterotrophic beings are those that need to INCORPORATE organic material to NOURISH them. Therefore, heterotrophs depend on the production of the autotrophs.

Autotrophic beings are those that can produce their own food, i.e., that make organic material from inorganic compounds.

Heterotrophic beings are those that need to incorporate organic material to nourish them. Therefore, heterotrophs depend on the production of the autotrophs.

BIOSPHERE is the SET of all of the ECOSYSTEMS of the PLANET.

Biosphere is the set of all of the ecosystems of the planet.

ECOSYSTEM is a system composed of biotic and ABIOTIC FACTORS in INTERACTION.

Ecosystem is a system composed of biotic and abiotic factors in interaction.

Abiotic factors are the nonliving elements that constitute a given ENVIRONMENT, like light, temperature, MINERALS, water, gases, atmospheric PRESSURE, ETC.

Abiotic factors are the nonliving elements that constitute a given environment, like light, temperature, minerals, water, gases, atmospheric pressure, etc.

Biotic factors are the LIVING beings (plants, ANIMALS, and MICROORGANISMS) that are part of a given ENVIRONMENT. Image DIVERSITY: biotic factors

Biotic factors are the living beings (plants, animals, and microorganisms) that are part of a given environment. Image Diversity: biotic factors

ECOLOGICAL niche is the set of PECULIAR activities, resources, and strategies that a SPECIES explores to survive and reproduce. Habitat is the place where the species lives to EXPLORE its ecological niche. In other words, it can be SAID that habitat is the “address” of the species and the ecological niche is the “profession” of the species.

Ecological niche is the set of peculiar activities, resources, and strategies that a species explores to survive and reproduce. Habitat is the place where the species lives to explore its ecological niche. In other words, it can be said that habitat is the “address” of the species and the ecological niche is the “profession” of the species.

Community is the set of POPULATIONS of living beings that LIVE in the same REGION and interact with each other.

In Ecology population is a set whose MEMBERS (living in a GIVEN place in a given time) are part of the same species. Community is a set of populations of different species (living in a given place in a given time).

Community is the set of populations of living beings that live in the same region and interact with each other.

In Ecology population is a set whose members (living in a given place in a given time) are part of the same species. Community is a set of populations of different species (living in a given place in a given time).

Population is the SET of INDIVIDUALS of the same SPECIES found in a GIVEN place in a given TIME.

Population is the set of individuals of the same species found in a given place in a given time.

Species is the set of living beings able to cross AMONG themselves generating FERTILE offspring.

This concept however does not apply to individuals of exclusive asexual reproduction and other DEFINITIONS have been proposed. For example, “species is a set of living beings that evolve in a common manner all of them considered ANCESTORS of the same type in relation to common descendants”.

Species is the set of living beings able to cross among themselves generating fertile offspring.

This concept however does not apply to individuals of exclusive asexual reproduction and other definitions have been proposed. For example, “species is a set of living beings that evolve in a common manner all of them considered ancestors of the same type in relation to common descendants”.

ECOLOGY is the FIELD of Biology that STUDIES the relations between LIVING BEINGS and between living beings and the environment.

Ecology is the field of Biology that studies the relations between living beings and between living beings and the environment.