A LEVEL ENVIRONMENTAL SCIENCE: Biomes
Terms in this set (33)
- north of tree line.
- cold-resistant, woody shrubs.
- caribou, reindeer, arctic hare, artic fox.
- precipitation = 13cm per year
- temperature range = -88 to 15 degrees C.
- precipitation = 48 cm per year.
- temperature range = -45 to 18 degrees C.
- coniferous trees, needle leaves.
- poor acidic soil conditions.
- moose, bear, wolf, lynx.
- precipitation = 150 cm per year.
- temperature range = 0 to 20 degrees C.
- deciduous trees e.g. oak.
- broad leaves that fall off during winter months.
- deer, squirrel, rabbit, fox etc.
- precipitation = 45 cm per year.
- temperature range = -5 to 25 degrees C.
- insufficient moisture to support tree growth.
- bison, horse, rabbits, coyote.
- precipitation = 50 cm per year.
- temperature range = 12 to 30 degrees C.
- grasses with scattered trees and shrubs.
- antelope, zebra, giraffe, lion, cheetah.
- precipitation = 300+ cm per year.
- temperature range = 20 to 30 degrees C.
- year round growth due to lack of seasons.
- large trees (e.g. mahogany).
- widest variety of species world wide.
global atmospheric circulation system
- surface wind always moves from high to low pressure.
- high pressure occurs when air sinks
- low pressure occurs when air rises.
- hadly, ferrel, polar cells.
nutrients are cycled through three stores - biomass, litter, soil.
the size of the store relates to the amount of nutrients in that store.
the flow of nutrients is influenced by processes such as decomposition and decay.
the change in structure and species composition of a community over time.
simplest type of succession. begins with bare surface with no life or soil present. first organisms to colonise are pioneer species, usually algae or lichens.
event will disrupt succession, e.g. fires or landslides. succession will begin again in the new conditions.
non-vegetated surfaces: lithosere (rock)
e.g. new volcanic land, emerging raised beach, retreat of a glacier.
pioneer species = lichen.
non-vegetated surfaces: psammosere (sand)
e.g. sand dunes.
pioneer species = marram grass.
non-vegetated surfaces: halosere (salt water)
e.g. salt marsh.
pioneer species = algae.
non-vegetated surfaces: hydrosere (fresh water)
e.g. lake, pond.
pioneer species = blue/green algae.
changes during succession
- increased size of organisms.
- energy flow becomes more complex.
- soil nutrients increases.
- biodiversity increases then falls as climax community is reached.
succession returned to an earlier stage.
succession kept at a lower level by humans/animals e.g. farming/grazing.
if the human activity that destroyed the climax community continues, then a new community of species will develop, e.g. farming.
a group of organisms of one species in a particular location.
calculation of population change
population growth rate = (birth rate - death rate) +/- net migration rate.
sum of the environmental factors (e.g. drought, competition) that restricts the biotic potential of an organism and limits numerical increase.
unrestricted growth of populations resulting in the maximum growth of that population. when the species has its highest birth rate and lowest death rate.
density dependent factors
proportional effect changes as population numbers change e.g. competition between species.
density independent factors
effect does not change proportionately when population changes e.g. weather.
growth curves: sigmoidal curve (S curve).
- three phases; lag phase, log phase, equilibrium phase.
- carrying capacity = maximum population that can be sustained.
S curves: lag phase
population growth is slow. less breeding aged species. adapting to new environments.
S curves: log phase
period of maximum growth. ideal conditions for food, space, and breeding partners.
S curves: equilibrium phase
birth and death rate are equal. density dependent factors keep population size in check.
growth curves: J curve (reason)
unlike in the natural world where overpopulation would lead to death due to diseases, starvation, and conflict, some species have overcome this e.g HUMANS.
phases of J curve
- start at a fast growth and then collapses due to overpopulation.
- ecosystem can no longer support the large number of animals in that system.
- occurs mostly in smaller ecosystems e.g. invertebrates and small animals.
individuals of the same species compete for food, space, and mates.
individuals of different species compete for food and space.