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a group of individuals of one species living in one area who can interbreed and interact with each other
nonliving environmental factors (e.g. temperature, water, sunlight, wind, rocks, and soil)
a population with no predation, parasitism, or competition, no immigration or emigration, and in an environment with unlimited resources
factors that limit population growth; divided into: density-dependent and density independent factors
factors that increase directly as the population density increases (e.g. competition, predation, disease)
factors whose occurence is unrelated to the population density (e.g. natural disasters)
convert light energy into chemical energy and have the greatest biomass of any trophic level
only about ___% of the energy stored in any trophic level is converted to organic matter at the next trophic level
gross primary productivity
the amount of energy converted to chemical energy by photosynthesis per unit time in an ecosystem
net primary productivity
the gross primary productivity minus the energy used by the primary producers for respiration
organisms at higher trophic levels have greater concentrations of accumulated toxins stored in their bodies than those at lower trophic levels
nutrients would not be recycled back to the soil to nourish plants, and there would be no food chain and no life without these
primary ecological succession
the rebuilding of an ecosystem in a lifeless area where soil has been removed
secondary ecological succession
when an existing community has been cleared by some disturbance that leaves the soil intact
large regions of Earth whose distribution depends on the amountof rainfall and the temperature in an area
biome that accounts for more than 20% of Earth's net carbon fixation (food production)
live in the nodules of the roots of legumes and convert free nitrogen into ammonium
depletion of oxygen in water because of increase of nutrients that cause eccessive growth of oxygen-depleting plants
organic material accumulates on the bottom of a lake body and reduces the depth of the lake
detritivores use up oxygen as they decompose the dead organic matter; the depletion of oxygen makes it impossible for other organisms to live
increased concentration of carbon dioxide in the air; carbon dioxide and water vapor in the air absorb much of the infared radiation reflect off the Earth
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