BIOL 2060 Lecture Notes - Tropical And Subtropical Moist Broadleaf Forests, Temperate Deciduous Forest, Intertropical Convergence Zone

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Published on 25 Nov 2012
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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 them
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
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:
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
temperate deciduous forest: eastern NA, eastern Asia, Europe
otemps fluctuate btwn winter and summer, precipitation evenly distributed
odeciduous trees dominate; more tree species than boreal
omany genera or plants+animals shared in those 3 separate regions
temperate grassland: areas dry for much of year
ohot summers, cold winters; converted to agriculture
oin some, most precipitation falls in water, others in summer
ovegetation = simple – perennial grasses, sedges, forbs (colourful)
oplants adapted to grazing and fire; store energy underground and resprout
cold desert: dry regions at middle to high latitudes; esp in continents in rain shadows of
mountain ranges
oseasonal temp changes great; dominated by few species of low-growing shrubs;
annual productivity is low b/c soils dry rapidly in spring
osurface of soil recharged w/ moisture in winter, plant growth concentrated in spring
opoor in species of most taxonomic groups, but lots of seeded plantssupports seed-
eating animals
hot desert: two belts – 30o N and S – where air descends, warms, picks up moisture
oscarce rainfall in summer, winter rains from ocean storms
oricher, structurally more diverse vegetation (cacti)
oannual plants germinate+ abundantly grow; pollination+dispersal of fruits
orodents, termites, ants, lizards, snakes
chaparral: western sides of continents, mid-latitude, cool ocean currents flow off-shore
ocool, wet winters; warm, dry summers
odominant plants: low growing shrubs and trees with tough evergreen leaves
oannual plants abundant, produce seeds that fall into soil small rodents
ovegetation is naturally adapted to survive periodic fires
thorn forest: equatorial sides of hot deserts
oclimate: semiarid – little rain in winter, heavy rain in summer
oplants similar to those in hot deserts; spiny shrubs+small trees=dominant (deciduous)
otropical savanna: expanses of grasses/grass-like plants with scattered trees
supports grazing and browsing mammals, large carnivores
if vegetation is not grazed, it reverts to dense thorn forest
tropical deciduous forest: closer to equator where length of rainy season increases
otaller trees, fewer succulent plants than TF; richer in plant+animal species
omost trees lose leaves during long, hot dry season, flower while leafless, pollinated by
animals; during hot dry season, biological activity is intense
obest soils for agriculture b/c contains more nutrients than wetter areas
most cleared for agriculture and cattle grazing
tropical evergreen forest: equatorial regions; total rainfalls >250cm/year; dry season <3mths
orichest in # of species of animals+plants; highest overall productivity of all
omost mineral nutrients are tied up in vegetation; soil needs fertilizers for agriculture