Topic 21 - Ecosystems and Conservation Flashcards
Biodiversity
The diversity of life considered at three levels: genetic diversity (variety of alleles and/or genes in a population, species, or group of species); species diversity (variety and relative abundance of species present in a certain area); and ecosystem diversity (variety of communities and abiotic components in a region).
Biogeochemical cycle
The pattern of circulation of an element or molecule among living organisms and the environment.
Carbon cycle
The movement of carbon among terrestrial ecosystem, aquatic ecosystem, and the atmosphere. Has been greatly modified by humans with the recent intensive use of fossil fuels.
Decomposers/detritivores
All living organisms convert organic to inorganic molecules (in cellular respiration, for example) but this trophic level is especially important in that role.
Denitrification
A microbially-facilitated process where nitrate (NO3−) is reduced and ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products.
Ecosystem services
All the benefits that humans derive, directly or indirectly, from ecosystem functions.
Factors that lead to differences in net primary productivity
Temperature, water availability, nutrient availability, amount of sunlight
Flux of elements
Constantly cycling from soil to living organisms, between trophic levels, the atmosphere and water bodies. The exact order and amount depends on the element. The Earth is an almost closed system for it.
Flux of energy
In most ecosystems it goes from the Sun, to primary producers, to primary, secondary, tertiary and quaternary consumers (in that order), and finally to detritivores. (Shortcuts are possible e.g. plants ->detritivores). The Earth is an open system for it.
Global warming
Causes geographic range shifts, phenology shifts (change in timing of seasonal events such as migration, flowering, hatching, which could be detrimental to species), evolutionary adaptation, extinctions, acidification of the oceans with detrimental effects for marine species with shells and corals.
Nitrification
The biological oxidation of ammonia (NH4) to nitrite (NO2) followed by the oxidation of the nitrite to nitrate (NO3), which plants can incorporate into their own tissues. Nitrates also are metabolized by denitrifying bacteria, which are especially active in water-logged anaerobic soils. The action of these bacteria tends to deplete soil nitrates, forming free atmospheric nitrogen.
Nitrogen cycle
The natural process by which nitrogen, either from the atmosphere or from decomposed organic material, is converted by soil bacteria to compounds assimilated by plants. This incorporated nitrogen is then taken in by other organisms and subsequently released, acted on by bacteria, and made available again to the nonliving environment.
Nitrogen fixation
The incorporation of atmospheric nitrogen (N2) into ammonia (NH3) which can be used to make many organic compounds. Occurs in only a few lineages of prokaryotes.
Sustainable practices
Practices that involve a planned use of environmental resources at a rate no faster than the rate at which they are naturally replaced.
Threats to biodiversity
Habitat destruction, habitat degradation, overexploitation, invasive species, pollution, climate change.
