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ENVB 3280 Lecture Notes - Tropical And Subtropical Moist Broadleaf Forests, Temperate Deciduous Forest, Intertropical Convergence Zone

Environmental Biology
Course Code
ENVB 3280

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Ch 52: Ecology and the Distribution of Life
ecology: scientific study of rich and varied interactions btwn organisms and environment
communities: systems embracing all the organisms loving together in the same area
ecosystems: systems embracing all organisms in an area plus their physical environment
environment: encompasses abiotic (physical+chemical ex water, minerals) and biotic (living
organisms) factors
interactions btwn organisms and environment are 2 way processes:
oorganisms both influence and are influenced by environment
understanding ecology allows us to manage ecosystems, to grow food, control pests, deal with
natural disasters, etc
ecologists become familiar with various environments and understand how organisms adapt to
climate: average of atmospheric conditions (temp, precipitation, wind direction, velocity)
found over long term [weather: short-term state of conditions]
ovary in different parts of world due to solar energy
diff in air temp largely determined by solar energy input
rate at which solar energy arrives on Earth per unit of Earth’s surface depends on angle of
ohigh latitudes (closer to poles) get less solar energy than equatorial places
ohigher latitudes have greater variation in day length and angle of arriving solar energy
over year more seasonal variation in temp
air temp decreases with elevation
oair rises, expands, pressure and temp dropmoisture released
global air circulation patterns result from global variation in solar energy input
intertropical convergence zone: the coming together of air masses. Air rises when it is heated
by sun, so warm air rises in tropics, which receive greatest solar energy input. Rising air is replaced by
air that flows in toward equator from N +S
oheavy rains fall as rising air cools and releases moisture
oshifts latitudinally with seasons, following zone of greatest energy input
ocan predict precipitation patterns in tropical and subtropical areas
air that replaces rising air in ICZ is replaced by air from aloft, that descends at 30o N and S
latitudes after having travelled away from equator in atmosphere
oair cooled+lost moisture while it rose to equator. Now, it descends, warms, takes up
moisture ex. Sahara and Australian deserts
at poles (little solar energy), air descends; responsible for global wind patterns
spinning of earth on its axis also influences surface winds b/c earth’s velocity is rapid at
equator, but relatively close to poles
ostationary air mass’ velocity=earth’s velocity at same latitude
oas air mass moves toward equator, meets a faster spin, and its rotational movement is
slower than earth’s beneath it

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oair masses moving latitudinally are deflected to right in N hemisphere (NH) and to left
in S hemisphere (SH)
those moving toward equator from N and S become northeast and south east
trade winds respectively
oair masses moving away from equator become westerly winds
oair rises to pass over mountains, cools; clouds form on windward side of mountains and
release moisture as rain/snow; on leeward side, dry air descends, warms, and again picks up
moisturerain shadow = dry area
these global air circulation patterns drive circulation patterns of surface ocean waters: currents
trade winds cause water to converge at equator until encountering continental land mass; water
splits so some moves north and south; transfers large amounts of heat at high latitudes
ocurrents move towards poles, water veers right in NH and left in SH, and turns
eastward until encountering another continent and is deflected laterally along shores
oin NH +SH, water flows toward equator along western sides of continents
changes in env’t require immediate responses, some gradual (plants, lizards)
morphological+physiological features let organisms function in variable env’t
some anticipate changes so they migrate or enter resting state (hibernation) before adverse
conditions come
most changes in physical environment happen independently of anything organisms do; others
influenced by activities or organisms
biome: terrestrial environment defined by grown forms of plants (forests, tundra)
oplant distribution influenced by temp and rainfall
oone set of graphs plots seasonal patterns of temp and precipitation at a site in a biome
osome graphs show activity patterns of different kinds of organisms / year; levels of
biological activity shown by width of horizontal bars
ospecies richness: number of species present in communities
boundary btwn biomes is arbitrary; gradually merge into another
tundra biome: arctic and high elevations in mountains everywhere
oin Arctic t, vegetation is underlain by permafrost—soil who water is permanently
frozen; soil may thaw in short summer
little precipitation but very wet b/c water can NOT drain through permafrost
plant grow for few months/year
animals migrate into area for summer or are dormant for most of year
otropical alpine t: photosynthesis and most bio activities continue (slowly)
more plant forms present
boreal forest: toward equator from Arctic t, lower elevations on mountains
owinders long and cold, summers short, warm
oevergreen tress b/c ready to photosynthesize as soon as it gets warm
oNH: has evergreen coniferous gymnosperms; SH: southern beeches
oTemperate evergreen forests: grow along western coasts of continents at middle to high
latitudes; winters mind and wet, summers cool and dry; earth’s tallest trees
ofew tree species; moose, hares; seeds of conifersrodents, birds, insects
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