Env. Geo. final exam

Why do biomes vary in their productivity?
temperature and precipitation (they change with elevation and latitude) are very imporstant determinants 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 forestssavannas: grasslands with sparse tree coversubject to fires b/c of lack of rainplants have adaptations to survive drought, heat, and fire
sparse vegetation (can be damaged by vehicles), but diverseoccur where pric. in uncommonwarm, dry, gigh-pressure climate conditionsplants/animals highly adapted to survive droughts, heat, and cold
temperate grasslands
Occur where there is enough rain to support grass but not enough for forestscomplex, diverse mix of grass and flowering plantsorganic-rich soils are made from roots and dead leaves
temperate shrublands
dry environments that support drought-adapted shrubs and trees, as well as grasscan be rich biologically and variable 
temperate forests deciduous and coniferous
d: trees and shrubs shed their leaves at the end of their growing seasonmoist, moderate climates but human impacts are extensive, making most native species somewhat threatenedc: 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 forestsslow growing
treeless landscape at high lat.

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s or on mountaintops with a very short growing seasonnot badly threatened

marine ecosystems
oceans cover 3/4 of earth’s surface and contribute to other ecosystemsmost marine communities depend on photosynthetic plants (phytoplankton) that support the food web
benthic and pelagic communities
b: at the bottomp: at the top
coral reefs
best known marine systemextraordinary biological productivity and diversity they are colonies of minute animals that live symbiotically with algaeendangered 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 shelterhumans 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 actionprevents most plant growth
lakes (freshwater)
warmer upper layerbelow is a colder deeper layerthermocliine 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 treesmarshes are wl’s w/o trees
streams and rivers
streams form when precipitation exceeds evaporation and water drains from the landas streams collect water and merge they form rivers
the variety of living thingsgenetic diversity: differences, genetically among speciesspecies diversity: # of kinds organismsecological 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)definitionmass extinctionpremature 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 radiationspremature extinction is happening today, the only difference is that it is b/c of human action
the human threats to biodiversityhabitat destruction, invasive species, pollution, population, and overharvesting
habitat destruction(loss or degredation)
biggest cause of extinctionloss: amt of habitats, forests, plowing grasslandsdegredation: fragmentation which is reducing habitats into small isolated patchescreating hab. islands, surrounded by some other hab.


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 habitatsif new organisms achieve “ecological release” they have nothing to control their populationthis causes decrease in global biodiversity
change # 2 we can increse numbers w/in species
“minion biota”: increasing things we likesyanthropes: 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 possibleendangered: imminent dnager of ext.threatened: likely to become endangeredvulnerable: 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