Acid Rain rain with a ph below 5.6; primarily due to the release of nitric and sulfuric oxides into the air from the burning of fossil fuels.

Transcription

1 ECOLOGICAL TERMS Acid Rain rain with a ph below 5.6; primarily due to the release of nitric and sulfuric oxides into the air from the burning of fossil fuels. Autotroph an organism that produces its own food (from inorganic compounds and sunlight). Biodiversity - The number of different species in an ecosystem as well as the genetic variety within those species the variety of life. Biomass The total weight of the dry living tissue in a trophic level. Community a collection of interacting populations that live in the same ecosystem. (the living portion of an ecosystem) Consumer an organism in a community that is heterotrophic Decomposer usually microorganisms that break down dead organic material into simpler substances. Ex. bacteria, fungi Detritus Decomposing dead organic matter and wastes (it often consists of loose, smaller fragments that have broken off). It is an important component of some food webs, such as forest floors where the primary energy source is not living autotrophs. Ex. marshes, estuaries, forest floor, streams. Detritivore - Small animals that feed on detritus. Ex. earthworms, crayfish, millipedes, fiddler crabs, springtails Ecology the study of organisms and how they interact with their environment. Ecosystem consists of the living communities and the nonliving (abiotic) factors in an environment. Food Chain the pathway that the transfer of energy and matter take in an ecosystem. (shows feeding sequence; involves producers, consumers, scavengers, and decomposers).

2 Food Web consists of all the interconnecting food chains in an ecosystem. Fossil Fuel a nonrenewable, energy-rich compound formed from decayed organic matter (once-living organisms). Greenhouse Effect the heat-trapping action of particular gases in our atmosphere (energy comes in as solar radiation, converted into heat, the heat cannot escape into space as easily). Global Warming an increase in the Earth's average surface temperatures (associated with an increase of greenhouse gases in the atmosphere) Herbivore a consumer that eats only plants. (a primary consumer) Heterotroph an organism that cannot make its own food. Niche - the specific role, function, and position of an organism in an ecosystem. Its job in the ecosystem. Organisms cannot succeed in an ecosystem unless there is an available niche. (the full range of physical and biological conditions in which an organism lives and how the organism uses those conditions includes where it lives, what it eats, its range of env. temperatures, how it interacts with other organisms, ) Nitrogen Cycle the pathway by which nitrogen moves through the environment (includes nitrogen fixation, denitrifying, ammonification). Nonrenewable Resource a resource that cannot be replenished as quickly as it is being consumed. Ex. fossil fuels. Omnivore a consumer that eats both producers (ex. plants) and consumers (ex. other animals). Ozone Layer a layer in the stratosphere that is composed of ozone (O 3 ). It helps shield the Earth from dangerous UV radiation. Producer an autotroph that provides food for a community. Renewable Resource a resource that can be replenished as quickly as it is being consumed. Ex. air, trees

3 Scavenger A larger animal that feeds on the remains of dead organisms (consume larger quantites of dead organic material). Ex. vultures, hyenas, gulls, crabs Trophic levels a step in the transfer of energy (and matter) in a food chain. "Matter cycles, Energy flows (one way)" Approximately 10% of the energy is passed from one trophic level the next one Ecological Pyramids - A diagram that represents the relative amounts of energy or matter in each trophic level of a food web. Ex. numbers pyramid, energy pyramid, biomass pyramid Primary Productivity - The rate at which organic matter (biomass) is created by producers in an ecosystem. Biological Magnification The increasing concentration of a harmful, and usually toxic, substance as it moves up the food chain. The toxins tend to be stored in the fatty tissues of the animal. Ex. DDT was 400x more concentrated in top carnivores (eagles, ospreys) than in the producers. Other pollutants that tend to biomagnify include mercury, lead, and PCBs. Nitrogen Fixation - The process where bacteria convert atmospheric nitrogen into ammonia. (Azobacter, Rhizobium in the root nodules of legumes) N 2 + 3H 2 2NH 3 (ammonia) Nitrification - The process where bacteria convert ammonia into nitrates. Ex. ammonia nitrites nitrates (Nitrosomonas, Nitrobacter) NH 3 NO - 2 NO - 3 (nitrates) Denitrification - The process where bacteria convert nitrates into nitrogen gas. Usually under low oxygen (anaerobic) conditions. (Thiobacillus) Eutrophication The process where bodies of water are overloaded with nutrients. It is often the result of human activities (artificial). Sources include fertilizer runoff, detergents, and leaking sewage. It can lead to the rapid growth of algae (algal bloom) in aquatic ecosystems that ultimately depletes the oxygen levels in the water and reduces water quality.

4 Dissolved oxygen levels drop as thick layers of algae at the water s surface block sunlight from penetrating past the water s surface and therefore reduce photosynthesis. Even worse is that when the excess algae die, decomposers consume the water s oxygen as they breakdown the dead algae. Succession The gradual replacement of one plant community by another one. Succession starts with pioneer species and proceeds towards the climax species. These changes are in response to natural and human disturbances. (Although these communities tend to be named after the dominant plant species, e.g. oak-hickory, there are certain animals associated with them) ex. bare rock lichens, mosses grasses, small shrubs birches, aspen (fast-growing trees) oaks, hickories, maples Pioneer Species The first plant species to colonize an area that is void of vegetation. An area may lack plants because the land area has only recently been formed (lava flow) primary succession or due to a disturbance (fire, clearcut) secondary succession. Climax Community A community dominated by plant species that are relatively stable and self-sustaining in a specific environment (unless removed by a disturbance) Ex. oak-hickory (temperate deciduous forest) Limiting Factor - A condition that restricts a population s growth. Ex. space, food availability, lack of particular nutrient, ph, oxygen. Carrying Capacity The maximum number of individuals, of a given species, that an environment can support for the long term the size of population would not negatively impact the environment. Water Cycle The pathway by which water cycles between the Earth's surface, ground, and atmosphere. (includes precipitation, evaporation, condensation, runoff, soil infiltration, ground water storage). Watershed An area of land that drains its water to a shared destination. (the water moves through a number of drainage pathways including streams and rivers). Non-Point Source Pollution The pollution of water from numerous, widespread locations. It can be difficult to pinpoint the sources of the pollution and even harder to regulate the pollution. Ex. fertilizer runoff from farms and lawns, oil spills in driveways.

5 Point Source Pollution The pollution of water from one location in a concentrated manner. Ex. Discharge pipe from a sewage treatment plant. Succession: the gradual replacement of one plant community by another. Brought about by changes in climate, in environment, or in the community (climatic succession, physiographic succession, biotic succession), and most frequently by erosion, dropping water levels, or invasion by another species. Succession due to external forces is allogenic, and autogenic when self-prompted. Overall, succession starts with pioneer species and proceeds to those more mature and longer lived (climax). Example: an empty lot taken over by weeds, then bushes, then flowering plants and finally trees. Primary Production: the total amount of energy and nutrients transformed by plants into biomass or chemical energy (roughly 1-3% efficiency for photosynthesis and.2% for the ecosphere as a whole). Productivity: the rate at which a group of organisms produces biomass.