What Is An Ecosystem An ecosystem is a natural unit consisting of all plants, animals and micro-organisms (biotic factors) in an area functioning together with all of the non-living physical (abiotic) factors of the environment.

Aquatic systems are those that contain plants and animals that predominantly depend on a significant amount of water to be present for at least part of the year.

CHAPARRALA dense, impenetrable thicket of shrubs or dwarf trees. A vegetation type dominated by shrubs and small trees, especially evergreen trees with thick, small leaves.

CORAL REEFA large underwater formation created from the calcium carbonate skeletons of coral animals; can also refer to the animals living on and near the coral reef.

DESERTA desert is a landscape form or region that receives very little precipitation. Deserts can be defined as areas that receive an average annual precipitation of less than 250 mm (10 in), or as areas in which more water is lost than falls as precipitation.In the Kppen climate classification system, deserts are classed as BWh (hot desert) or BWk (temperate desert).

GREATER YELLOWSTONE ECOSYSTEMGreater Yellowstone is the last remaining large, nearly intact ecosystem in the northern temperate zone of the Earth and is partly located in Yellowstone National Park. Conflict over management has been controversial, and the area is a flagship site among conservation groups that promote ecosystem management. The Greater Yellow Ecosystem (GYE) is one of the world's foremost natural laboratories in landscape ecology and geology and is a world-renowned recreational site. It is also home to the animals of Yellowstone.

HUMAN ECOSYSTEMHuman ecosystems are complex cybernetic systems that are increasingly being used by ecological anthropologists and other scholars to examine the ecological aspects of human communities in a way that integrates multiple factors as economics, socio-political organization, psychological factors, and physical factors related to the environment.

LARGE MARINE ECOSYSTEMAny marine environment, from pond to ocean, in which plants and animals interact with the chemical and physical features on the environment.

LITTORAL ZONEThe region of the shore of a lake or sea or ocean / the shore of a sea or ocean.

MARINE ECOSYSTEMAny marine environment, from pond to ocean, in which plants and animals interact with the chemical and physical features of the environment.

RAINFORESTMixed rainforest or mixed forest) is a rainforest classification where eucalypt forest grows in combination with Cool Temperate rainforest species.

SAVANNAA tropical or subtropical grassland containing scattered trees and drought-resistant undergrowth.

SUBSURFACE LITHOAUTOTROPHIC MICROBIAL ECOSYSTEMA minute life form; a microorganism, especially a bacterium that causes disease.

TAIGAA moist sub arctic coniferous forest that begins where the tundra ends and is dominated by spruces and firs.

TUNDRA A type of ecosystem dominated by lichens, mosses, grasses, and woody plants. Tundra is found at high latitudes (arctic tundra) and high altitudes A treeless plain characteristic of the arctic and sub arctic regions.

URBAN ECOSYSTEMIs the subfield of ecology which deals with the interaction of plants, animals and humans with each other and with their environment in urban or urbanizing settings. Analysis of urban settings in the context of ecosystem ecology (looking at the cycling of matter and the flow of energy through the ecosystem) can result in healthier, better managed communities. Studying the factors which allow wild plants and animals to survive (and sometimes thrive) in built environments can also create more livable spaces. It allows people to adapt to the changing environment while preserving the resources.

The dark arrows represent the movement of this energy .The movement of the inorganic nutrients is represented by the open arrows.

Energy Flow Through the Ecosystem

The diagram above shows how both energy and inorganic nutrients flow through the ecosystem.

To summarize: In the flow of energy and inorganic nutrients through the ecosystem, a few generalizations can be made:The ultimate source of energy (for most ecosystems) is the sunThe ultimate fate of energy in ecosystems is for it to be lost as heat.Energy and nutrients are passed from organism to organism through the food chain as one organism eats another.Decomposers remove the last energy from the remains of organisms.Inorganic nutrients are cycled, energy is not.

Food Chains and Webs:A food chain is the path of food from a given final consumer back to a producer. For instance, a typical food chain in a field ecosystem might be:The real world, of course, is more complicated than a simple food chain. While many organisms do specialize in their diets (anteaters come to mind as a specialist), other organisms do not. Hawks don't limit their diets to snakes; snakes eat things other than mice. Mouse eats grass as well as grasshoppers, and so on.

A more realistic depiction of who eats whom is called a food, web; an example is shown below: It is when we have a picture of a food web in front of us that the definition of food chain makes more sense. We can now see that a food web consists of interlocking food chains, and that the only way to untangle the chains is to trace back along a given food chain to its source.

The food webs you see here are grazing food chains since at their base are producers which the herbivores then graze on. While grazing food chains are important, in nature they are outnumbered by detritus-based food chains. In detritus-based food chains, decomposers are at the base of the food chain, and sustain the carnivores which feed on them. In terms of the weight (or biomass) of animals in many ecosystems, more of their body mass can be traced back to detritus than to living producers.

PYRAMIDSThe concept of biomass is important. It is a general principle that the further removed a trophic level is from its source (detritus or producer), the less biomass it will contain (biomass here would refer to the combined weight of all the organisms in the trophic level).

This Reduction In Biomass Occurs For Several Reasons: Not everything in the lower levels gets eaten.Not everything that is eaten is digested.energy is always being lost as heat.

It is important to remember that the decrease in number is best detected in terms or biomass. Numbers of organisms are unreliable in this case because of the great variation in the biomass of individual organisms. A generalization exists among ecologists that on average, about 10% of the energy available in one trophic level will be passed on to the next; this is primarily due to the 3 reasons given above. Therefore, it is also reasonable to assume that in terms of biomass, each trophic level will weigh only about 10% of the level below it, and 10x as much as the level above it.

Roles Of Organisms In An EcosystemOrganisms can be either producers or consumers in terms of energy flow through an ecosystem.

Producers convert energy from the environment into carbon bonds, such as those found in the sugar glucose. Plants are the most obvious examples of producers; plants take energy from sunlight and use it to convert carbon dioxide into glucose (or other sugars). Algae and cyanobacteria are also photosynthetic producers, like plants. Other producers include bacteria living around deep-sea vents. These bacteria take energy from chemicals coming from the Earth's interior and use it to make sugars. Other bacteria living deep underground can also produce sugars from such inorganic sources. Another word for producers is autotrophs.

Consumers get their energy from the carbon bonds made by the producers. Another word for a consumer is a heterotroph. Based on what they eat, we can distinguish between 4 types of heterotrophs:A trophic level refers to the organisms position in the food chain. Autotrophs are at the base. Organisms that eat autotrophs are called herbivores or primary consumers.

consumer trophic level food source Herbivores primary plants Carnivores secondary or higher animals Omnivores all levels plants & animals Detritivores - - - - - - - - - - -detritus

An organism that eats herbivores is a carnivore and a secondary consumer. A carnivore which eats a carnivore which eats a herbivore is a tertiary consumer, and so on. It is important to note that many animals do not specialize in their diets.Omnivores (such as humans) eat both animals and plants. Further, except for some specialists, most carnivores don't limit their diet to organisms of only one trophic level. Frogs, for instance, don't discriminate between herbivorous and carnivorous bugs in their diet. If it's the right size, and moving at the right distance, chances are the frog will eat it. It's not as if the frog has brain cells to waste wondering if it's going to mess up the food chain by being a secondary consumer one minute and a quaternary consumer the next.

Components of an Ecosystem

ABIOTIC COMPONENTSBIOTIC COMPONENTSSunlightPrimary producersTemperatureHerbivoresPrecipitationCarnivoresWater or moistureOmnivoresSoil or water chemistry (e.g., P, NH4+)Detritivoresetc.etc.All of these vary over space/time

Processes of EcosystemsThis figure with the plants, zebra, lion, and so forth illustrates the two main ideas about how ecosystems function: ecosystems have energy flows and ecosystems cycle materials. These two processes are linked, but they are not quite the same (see Figure 1).

Figure 1. Energy flows and material cycles.Energy enters the biological system as light energy, or photons, is transformed into chemical energy in organic molecules by cellular processes including photosynthesis and respiration, and ultimately is converted to heat energy. This energy is dissipated, meaning it is lost to the system as heat; once it is lost it cannot be recycled. Without the continued input of solar energy, biological systems would quickly shut down. Thus the earth is an open system with respect to energy.28