BIOL 331 Lecture Notes - Marine Biology, Species Pool, Insular Biogeography

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What is a Biome?
Biome is a terrestrial environment defined by the growth forms of its plants.
Species richness the number of species present in its communities.
o Found in Arctic at high elevations in mountains at all latitudes
o Vegetation consists of low-growing perennial plants underlain by permafrost
o Little precipitation, lowland Arctic tundra is very wet (no drain source).
o Plants grow for only a few months each year
o Most Arctic tundra animals either migrate or remain dormant for most of the year.
o Tropical alpine tundra is not underlain by permafrost.
o Found toward the equator Arctic tundra and at lower elevations on temperate-zone
o Winters are long and very cold; summers are short (favours trees w/evergreen leaves).
o Boreal forests of the N. Hemisphere are dominated by evergreen coniferous
gymnosperms; in S. Hemisphere the dominant trees are southern beeches.
o Temperate evergreen forests also grow along the western coasts of continents at
middle to high latitudes in both hemispheres; winters are mild but very wet and
trees exist.
o Found in eastern N. America, E. Asia, and Europe.
o Temperatures fluctuate dramatically and precipitated is evenly distributed.
o Deciduous trees dominate these forests.
o More trees live here than in boreal forests.
o 
o Receive most of their scarce rainfall in summer; also receive winter rains from storms
that form over the mid-latitude oceans.
o Driest large regions are in the center of Australia and the middle of the Sahara Desert.
o Except in driest regions, hot deserts have richer and structurally more diverse
vegetation than cold deserts.
o A rich fauna of rodents, termites, ants, lizards, and snakes.
o Found on the western sides of continents at mid-latitudes where cool ocean currents
flow off-shore.
o Winters are cool and wet; summers are warm and dry
o Dominant vegetation are low-growing shrubs and trees with tough, evergreen leaves.
o Annual plants are abundant; supports large populations of small rodents.
o As length of the rainy seasons increases, tropical deciduous forest replaces thorn
o Have taller trees and fewer succulent plants than thorn forests; are much richer in plant
and animal species.
o Soils of the tropical deciduous forest biome are some of the best soils in the tropics for
What is a Biogeographic Region?
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