Ecosystem- All the organisms in a given area as well as the abiotic factors with which they interact; a community and its physical environment.

Community- All the organisms that inhabit a particular area; an assemblage of populations of different species living close enough together for potential interaction.

Prevalent Vegetation- Kinds of dominant plants; determines what animals live there.

Stability- the ability for an ecosystem to resist change and return to it original species composition after a disturbance.

Biodiversity- All of the variety of life; usually refers to the variety of species that make up a community; concerns both species richness (total number of species) and the total relative abundance of the different species.

Trophic Structure- The different feeding relationships in an ecosystem, which determine the route of energy flow and the pattern of chemical cycling.

Interspecific Competition- competition for resources between plants, animals or betweens decomposers when resources are short in supply.

Competitive Exclusion Principal- The concept that when populations of two similar species compete for the same resources, one population with use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population.

Niche- a populations role in the community/ sum of its use of the biotic and abiotic resources in it habitat.

Predation- An interaction between species in which one species, the predator, eats the other, the prey.

Predator- A consumer in a biological community.

Prey- An organism eaten by a predator. Can be another animal, or a plant.

Coevolution- Reciprocal adaptations between predator and prey; the mutual influence on the evolution of two different species interacting with each other an reciprocally influencing each others adaptations.

Batesian Mimicry- A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators. The unpalatable species must be more abundant than the palatable species, or else the mimicry will not be as effective.

Müllerian Mimicry- A mutual mimicry by two unpalatable species.

Keystone Species- Species that are not usually abundant in a community, yet exert strong control on the community structure by the nature of their ecological roles or niches. Example: Pisaster Sea Stars control the population of mussels which are the best competitors for resources

Resource Partitioning- The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species.

Symbiotic Relationship- An interspecific relationship in which one species, the symbiont, lives in or on another species, the host.

Parasitism- A symbiotic relationship in which the symbiont (parasite) benefits at the expense of the host by living either within the host (as an endoparasite) or outside the host (as an ectoparasite).

Commensalism- A symbiotic relationship i which the symbiont benefits but the host is neither help or harmed.

Mutualism- a symbiotic relationship in which both participants benefit.

Disturbance- a force that changes a biological community and usually removes organisms from it. Disturbances such as fire and storms play a pivotal role in structuring many biological communities.

Ecological Succession- Transition in species compositions of a biological community, ofter following ecological disturbance of a community; the establishment of a biological community in an area virtually barren of life.

Primary Succession- A type of ecological succession that occurs in a virtually lifeless area where is were originally no organisms and where soil has not yet yet formed.

Secondary Succession- A type of ecological succession that occurs where an existing community has been cleared by some disturbance, leaving soil intact.

Climax Community- idea of a final stage of community, all succession leads to it.

Energy Flow- The passage of energy through the components of an ecosystem.

Chemical Cycling- the use and reuse of chemical elements in an ecosystem.

Food Chain- The pathway along which food is transferred from trophic level to tropic level, beginning with producers.

Producers (autotroph)- Organisms that make organic food molecules from CO2, H2O, and other inorganic, raw materials; a plant, alga, or other autotrophic bacterium.

Consumer (heterotroph)- All organisms above producers, dependent on producers.

Primary Consumer- An herbivore; an organism in the trophic level of an ecosystem that eats plants or algae.

Secondary Consumer- A member of the trophic level consisting of carnivores that eat herbivores.

Tertiary Consumer- A member of the trophic level consisting of carnivores that eat mainly other carnivores.

Quaternary Consumer- An organism that eats tertiary consumers.

Detritivore- a consumer that derives its energy from non-living organic material (detritus) and thus returns the energy back into the food chain or web.

Decomposer - an organism (often times bacteria and fungi) that breaks down large organic molecules or compounds into simpler molecules or compounds and eventually into inorganic nutrients that are released into the environment.

Detritus- Dead organic matter.

Decomposition- The breaking down of organic materials into inorganic ones.

Food Web- The elaborate, interconnected feeding relationships in an ecosystem.

Biomass- the dry weight of organic matter comprising a group of organisms in a particular habitat.

Primary Production- The amount of light energy converted to chemical energy (organic compounds) by autotrophs in an ecosystem during a given period of time.

Energy Pyramid- A diagram that illustrates the energy flow through feeding relationships.

Abiotic Reservoir- The part of the ecosystem where a chemical (eg. carbon) accumulates or is stockpiled outside of living organisms.

Transpiration- Evaporation of water from the leaves of plants into the atmosphere.

Nitrates and Ammonium Ions- Used in plants at forms of Nitrogen to make amino acids and proteins.

Nitrogen Fixation-Conversion of N2 in atmosphere to ammonia, which later becomes ammonium.

Phosphates- Compounds containing PO4³–, released into soil through the weathering of rock.

Hubbard Brook Experimental Forest- A deciduous forest in the White Mountains where nutrients dynamics are monitored.

Unaltered Location-Natural environment.

Altered Location- An Environment that humans have affected in some way.

Eutrophication- Becoming gradually more productive due to over-exposure to nutrients like phosphorus and nitrogen.

Zoned Reserve- An extensive region of land that includes one or more areas undisturbed by humans, surrounded by lands that have been changed by human activity and are used for economic gain. The surrounding lands act as a shield from human disturbance.