Chapter 5 - Environmental Systems and Ecosystem Ecology Flashcards
hypoxia
the condition of extremely low dissolved oxygen concentration in a body of water
feedback loop
a circular process in which a systems output serves as input to that same system
negative feedback loop
a feedback loop in which out put of one type acts as input that moves the system in the opposite direction. the input and output essentially neutralize each others effects, stabilizing the system
positive feedback loop
a feedback loop in which output of one type acts as input that moves the system in the same direction. the input and output drive the system further towards on extreme or another
emergent tree
an especially tall tree that protrudes above the canopy of tropical rain-forest
dynamic equilibrium
the state reached when processes within a system are moving in opposing directions at equivalent rates so that their effects balance out
homeostasis
the tendency of a system to maintain constant or stable internal conditions
runoff
the water from precipitation that flows into streams, rivers, lakes, and ponds, and (in many cases) eventually to the ocean
hydrosphere
all water- salt or fresh, liquid, ice, and vapor- in surface bodies, underground, and in the atmosphere
eutrophication
the process of nutrient enrichment. increased production of organic matter, and subsequent ecosystem degradation in a water body
airshed
the geographic area that produces air pollutants likely to end up in a waterway
estuary
an area where a river flows into the ocean, mixing fresh and salt water
lithosphere
the outer layer of earth, consisting of crust and uppermost mantle and located just above the asthenosphere, more generally the solid part of earth, including rocks, sediments, and sail at the surface and extending many miles underground
primary production
the conversion of solar energy to the energy of chemical bonds in sugars during photosynthesis, performed by autotrophs
gross primary production
the energy that results when autotrophs convert solar energy to the energy of chemical bonds in sugars during photosynthesis. autotrophs use a portion of this production to power their own metabolism, which entails oxidizing organic compounds by cellular respiration
net primary production
the energy or biomass that remains in an ecosystem after autotrophs have metabolized enough for their own survival through cellular respiration. net primary production is the energy or biomass that is available for consumption by heterotrophs
net primary productivity
the rate at which net primary production is produced
secondary production
the total biomass that heterotrophs generate by consuming autotrophs
productivity
the at which plants convert solar energy to biomass. ecosystems whose plants convert solar energy to biomass rapidly are said to have high productivity
nutrient
an element or compound that organisms consume and require for survival
macronutrients
elements and compounds required in relatively large amounts by organisms. examples include nitrogen, carbon, and phosphate
micronutrients
elements and compounds required in relatively small amounts by organisms. examples include zinc, copper, and iron
ecotone
a transitional zone where ecosystems meet
landscape ecology
the study of how landscape structures affects the abundance, distribution, and interaction of organisms. this approach to the study of organisms and their environment. landscape studies follow broad geographical areas that include multiple ecosystems
patch
in landscape ecology, spatial area within a landscape, depending on a researchers perspective patches may consist of habitat for a particular organism, or community, or ecosystem. an array of patches forms a mosaic
mosaic
in landscape ecology, a spatial configuration of patches arrayed across a landscape
nutrient cycle (biogeochemical cycle)
the comprehensive set of cycle pathways by which a given nutrient moves through the environment
reservoir (pool)
an artificial water body behind a dam that stores water for human use
residence time
(1) in a biogeochemical cycle, the amount of time a nutrient remains in a given pool or reservoir before moving to another. (2) in the atmosphere, the amount of time a gas molecule or pollutant stays aloft
flux
the movement of nutrients among pools or reservoirs in a nutrient cycle
source
in a nutrient cycle, a pool that releases more nutrients than it accepts
sink
in a nutrient cycle, a pool that accepts more nutrients than it releases
water cycle (hydrologic cycle)
the flow of water - in liquid, solid, or gaseous form - through our biotic and abiotic environment
evaporation
the conversion of a substance from a liquid to a gaseous form
transpiration
the release of water vapor by plants through their leaves
precipitation
water that condenses out of the atmosphere and falls into earth in droplets or crystals
ground water
water held in aquifers underground
aquifer
an underground water reservoir
water table
the upper limit of groundwater held in an aquifer
carbon cycle
a major nutrient cycle consisting of the routes that carbon atoms take through the nested networks of environmental systems
nitrogen cycle
a major nutrient cycle consisting of the routes that nitrogen atoms take through the nested networks of environmental systems
nitrogen fixation
the process by which inert nitrogen gas combines with hydrogen to form ammonium ions (NH4+), which are chemically and biologically active and can be taken up by plants
nitrogen-fixing bacteria
bacteria that live independently in the soil or water, or those that form mutualistic relationships with many types of plants and provide nutrients to the plants by converting gaseous nitrogen to a usable form
nitrification
the conversion by bacteria of ammonium ions (NH4+) first into nitrite ions (NO2-) and then into nitrate ions (NO3-)
denitrifying bacteria
bacteria that convert the nitrates in soil or water to gaseous nitrogen and release it back into the atmosphere
Haber-Bosch process
a process to synthesize ammonia on an industrial scale. developed by german chemistFritz Haber and Carl Bosch, the process has enabled humans to double the natural rate of nitrogen fixation on earth and thereby increase agricultural productivity, but it has also dramatically altered the nitrogen cycle
phosphorus cycle
a major nutrient cycle consisting of the routes that phosphorus atoms take through the nested networks of environmental systems
