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17 Cards in this Set
- Front
- Back
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what are megafauna?
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animals larger than 45kg (100 lb)
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the growth form of a plant is an evolutionary response to?
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the selection pressures of the terrestrial environment (aridity, high and subfreezing temperatures, intense solar radiation, nutrient poor soils, grazing, crowding by neighbors)
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what is land use change? what human activities have altered the earth's land surface?
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the effects of land conversion and resource extraction by humans; most have been altered by agriculture, forestry, and livestock grazing - smaller amount by urban development and transportation corridors
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why are the potential and actual distributions of biomes different?
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the alteration of the earth's land surface by human activities
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name and describe the 5 layers of plants that could occur in tropical rainforests
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emergent trees = rise above other canopy trees (evergreen trees that rise 30-40 m above ground)
lianas = woody vines that utilize trees for support epiphytes = plants that grow on tree branches understory = plants that grow in the shade of the canopy shrubs and forbs = broad leaved herbaceous plants that occupy the forest floor |
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what is desertification?
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long term droughts in association with unsustainable grazing practices can result in loss of plant cover and soil erosion
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why are grasslands well suited for agricultural use?
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grasses grow more roots than stems and leaves - the rich organic matter that accumulates in the soils as a result enhances their fertility
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compare and contrast the terms mallee, fynbos, matorral, maquis, and chaparral
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zones characterized by a Mediterranean climate
mallee = Australia fynbos = South Africa matorral = chile maquis = around the Mediterranean Sea chaparral = North America |
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the biota of freshwater ecosystems reflect?
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the physical characteristics of water (velocity - flowing streams and rivers vs lakes and ponds, temperature, how far light can penetrate it - clarity, chemistry - salinity, O2 concentration, nutrient status, pH)
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the river continuum concept was developed to? (figure 3.13)
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describe changes of composition of biological communities in streams and rivers due to variation in stream order and channel size in both physical and biological characteristics of a stream; first order streams pool together to form second order etc; stream order affects environmental conditions, community composition, and the energy and nutrient relationships of communities within the stream
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Compare and contrast shredders and collectors
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shredders are organisms adapted to tear up and chew leaves; more abundant in the higher parts of the stream
collectors are organisms that collect fine particles from the water; more abundant in the lower parts of the stream. |
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how have human effects been significant and extensive on lotic systems?
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fourth and higher order rivers have been altered by pollution, increases in inputs of sediments, and introductions of non-native species; also have been used as conduits for the disposal of sewage and industrial wastes; excessive application of fertilizers results in runoff and leaching of nutrients into ground water, which eventually reaches rivers; deforestation increases sediment inputs which can reduce water clarity, alter benthic habitat and inhibit gill function in many aquatic organisms; sport fish introduction have lowered the diversity of native species in both stream and lake ecosystems
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where do lentic systems occur?
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lentic systems, lakes and other still waters, occur where natural depressions have filled with water or where humans have dammed rivers to form reservoirs
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compare and contrast the pelagic zone, littoral zone, and the benthic zone of a lake
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the pelagic zone is inhabited by plankton; phytoplankton hang out near the surface while zooplankton are dispersed throughout the pelagic zone; the littoral zone is where the photic zone reaches to the lake bottom where macrophytes join with floating and benthic phytoplankton to produce energy by photosynthesis; the benthic zone has detritus derived from the other zones and serves as an energy source for animals fungi and bacteria; usually coldest part of a lake and has the least oxygen concentration
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how are estuaries characterized?
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characterized by variations in salinity associated with the flow of fresh river water into the ocean and the influx of salt water flowing inland from the ocean as tides rise
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what is the overkill hypothesis?
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Paul Martin's theory that the rapidity of the extinctions and the greater proportion of large animals that disappeared reflected the hunting efficiency of those early humans; larger animals have lower reproduction rates, therefore giving this theory the name
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research at LTER sites is providing?
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research is providing a view of how environmental change, including climate change, may influence terrestrial biomes and marine ecosystems in the future
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