Env. Geo. final exam

Why do biomes vary in their productivity?

temperature and precipitation (they change with elevation and latitude) are very imporstant determinants


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Landforms such as mountains, and winds also influence biomes

vertical zonation
a term applied to vegetation zones defined by altitude

brad types of biological communites with similar climate conditions, growth patterns, and vegetation types


biological productivity varies and human use of biomes depends on that factor

humid tropical regions

they support one of the most complex and biologically rich biome types. All kinds of tropical forests have a lot of rainfall and uniform temperatures
tropical rainforests

occur where rainfall is abundant and temps are warm to hot yr round


soil is thin, acidic, and nutrient-poor, but many species types


nutrients mostly contained in living org.s

cloud forests

found in tropical forests, high in the mountains where fog and mist keep vegetation wet all the time


soil is thin, acidic, and nutrient-poor but many species


nutrients mainly found in living org.s

tropical seasonal forests

These tropical regions have distinct wet and dry seasons, but temps remain hot all yr.


they are drought-tolerant forests


soils have higher nutrient levels


highly endangered b/c they are commonly degradaded by human habitation

tropical savannas and grasslands

grasslands: too little rainfall to suppprt forests

savannas: grasslands with sparse tree cover

subject to fires b/c of lack of rain

plants have adaptations to survive drought, heat, and fire


sparse vegetation (can be damaged by vehicles), but diverse

occur where pric. in uncommon

warm, dry, gigh-pressure climate conditions

plants/animals highly adapted to survive droughts, heat, and cold

temperate grasslands

Occur where there is enough rain to support grass but not enough for forests

complex, diverse mix of grass and flowering plants

organic-rich soils are made from roots and dead leaves

temperate shrublands

dry environments that support drought-adapted shrubs and trees, as well as grass

can be rich biologically and variable


temperate forests


deciduous and coniferous

d: trees and shrubs shed their leaves at the end of their growing season

moist, moderate climates but human impacts are extensive, making most native species somewhat threatened

c: needle bearing trees, grow in a wide range of temperature and moisture conditions.

temperate rainforest
the wettest coastal forests which are cool and rainy, often with a lot of fog. condensations helps
boreal forests

many conifers in these northern forests

slow growing


treeless landscape at high lat.s or on mountaintops with a very short growing season

not badly threatened

marine ecosystems

oceans cover 3/4 of earth’s surface and contribute to other ecosystems

most marine communities depend on photosynthetic plants (phytoplankton) that support the food web

benthic and pelagic communities

b: at the bottom

p: at the top

coral reefs

best known marine system

extraordinary biological productivity and diversity


they are colonies of minute animals that live symbiotically with algae

endangered community

coral bleaching
the whitening of reefs due to stress leads to coral death


salt tolerant trees that grow along warm coasts around the world.

help stabalize shorelines, provide shelter

humans have been cutting many down and they have also been destroyed/degraded

bays where rivers empty into the sea, mixiing fresh water and salt water
salt marshes

shallow wetlands flooded regularly with seawater


biologically diverse

tide pools

depressions in a rocky shoreline that are flooded at high tide. lots of wave action

prevents most plant growth

lakes (freshwater)

warmer upper layer

below is a colder deeper layer

thermocliine is the sharp temperature boundary between these two

conditions that affect the characteristics of an aquatic community

nutrient availabilit, suspended matter, depth, temperature, currents, bottom characteristics, currents, connections to other systems

wetlands and different types

shallow ecosystems that land surface is saturated or submerged at least part of the yr

swamps are wl’s with trees

marshes are wl’s w/o trees

streams and rivers

streams form when precipitation exceeds evaporation and water drains from the land

as streams collect water and merge they form rivers


the variety of living things

genetic diversity: differences, genetically among species

species diversity: # of kinds organisms

ecological diversity: the complexity of a biological community


number of species that may be alive today
3-50 million
areas with high biodiversity
land by the equator and areas isolated by water, deserts, or mountains
benefits of biodiversity

-many species make important contributions to human food supplies

-rare species can provide medicines

-supports stability in the ecoysystem

-nature-based ativities

-part of people’s culture

change to biosphere # 1 (extinction)


mass extinction

premature extinction

the elimination of a species (natural process always happening)

mass extinction is abrupt rise over natural rate, there have been 5 in the past, followed by radiations

premature extinction is happening today, the only difference is that it is b/c of human action



the human threats to biodiversity

habitat destruction, invasive species, pollution, population, and overharvesting

habitat destruction

(loss or degredation)

biggest cause of extinction

loss: amt of habitats, forests, plowing grasslands

degredation: fragmentation which is reducing habitats into small isolated patches

creating hab. islands, surrounded by some other hab. type

problems with hab. islands
some species can’t survive if island is too small, can’t support large pop., need more gen. diversity, not as many species
minimum viable population
the number of individuals needed for long-term survival of rare and endangered species
factors that affect the success and biodiversity of habitat islands
distance from colonization source, island size, extinction
(bioinvasion) change # 3

introducing exotic species to habitats

if new organisms achieve “ecological release” they have nothing to control their population

this causes decrease in global biodiversity

change # 2

we can increse numbers w/in species

“minion biota”: increasing things we like

syanthropes: we don’t try to increase, but something does well in a certain environment

why save biodiversity?

nature has instrumental value: benefits humans (food, drugs, economy, cultural value “biophilia” means people have love of life)


nature has intrinsic value: ethical justification

Endangered species act

seek to identify all endangered species and pops and to save as much biodiversity as possible

endangered: imminent dnager of ext.

threatened: likely to become endangered

vulnerable: rare or have been depeleted

keystone species
major effects on ecologincal functions and whose elimination would affect many others
convention of international trade in endangered species
no international trade w endangered or threatened animals