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Lecture

BMEN 515 Lecture Notes - Alpine Tundra, Permafrost, Species Richness


Department
Biomedical Engineering
Course Code
BMEN 515
Professor
William Huddleston

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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.
TUNDRA
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.
BOREAL FOREST AND TEMPERATE EVERGREEN FOREST
o Found toward the equator Arctic tundra and at lower elevations on temperate-zone mountains.
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

trees, but only a few species of trees exist.
TEMPERATE DECIDUOUS FOREST
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.
HOT DESERT
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.
CHAPARRAL
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.
TROPICAL DECIDUOUS FOREST
o As length of the rainy seasons increases, tropical deciduous forest replaces thorn forests.
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 agriculture.
What is a Biogeographic Region?
Biogeography: the study of the patterns of distribution of populations, species, and ecological communities across
Earth.
Biogeographic regions are based on the taxonomic composition of the organism living in them; boundaries are set
where species compositions change dramatically over short distances.
Species found only within a certain region is said to be endemic to that region. Remote islands typically have distinctive
endemic biotas b/c water barriers greatly restrict immigration.
Three scientific advances changed the field of biogeography
Three scientific advances changed biogeography into the field it is today: 1. Acceptance of the theory of continental
drift, 2. the development of phylogenetic taxonomy, 3. The development of the theory of island biogeography.
CONTINENTAL DRIFT: Carolus Linnaeus believed that all organisms had been created in one place from which they later
dispersed.
PHYLOGENETIC TAXONOMY: method of reconstructing phylogenetic relationships among organisms.
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