Environmental Engineering Reference
In-Depth Information
which the birds feed, while the cattle are not affected in either a positive or negative way by the egrets' presen-
ce.
In amensalistic relationships, one organism harms or inhibits another while remaining unaffected itself. Only
limited examples of amensalism are understood because of the difficulty in proving that one species does not in
some way benefit from the harm it has caused to another. A common example, though, is the fungus Penicilli-
um notatum, which produces the antibiotic penicillin. Penicillin inhibits the growth of certain types of bacteria,
but it appears that the Penicillium is unaffected.
Biomes: Terrestrial and Aquatic
Throughout the planet are a variety of biomes, large ecological areas dominated by a particular plant type. The
location of biomes is based on many factors, including temperature, precipitation, soil type and characteristics,
and oceanic and atmospheric circulation. Precipitation and temperature are the main influence on vegetation
type and, therefore, on biomes.
Aquatic biomes are slightly more complicated to define and are not grouped the same way as terrestrial bio-
mes. Salinity, temperature, nutrients, currents, depth, wave action, and bottom substrate, as well as animal life,
all help to define an aquatic biome. Aquatic biomes include lakes, rivers, streams, ponds, wetlands (freshwater
and marine), estuaries, and coral reefs.
The Earth has ten major terrestrial biomes: tropical rain forest, tropical dry forest, temperate rain forest, tem-
perate deciduous forest, boreal forest (taiga), savanna, chaparral, temperate grassland, tundra, and desert. The
following chart summarizes the main characteristics of each biome.
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