Population & Sustainability Flashcards
r- and k-strategists
represent 2 ends of a continuum of strategies adopted by living things
k-strategists
species who population is determined by carrying capacity
r-strategists
population size increases so quickly it can exceed capacity before limiting factors start to have an effect
most important influence on population growth
physical rate (r) at which individuals can reproduce- bacteria and pioneer species
which colonise during succession first
pioneer r-strategist during fast population growth before k-strategists disperse to other habitats as limiting factors take affect
carrying capacity
the maximum population size that can be maintained over a period in a particular habitat
limiting factor
factor whose magnitude slows down the rate of a natural process
competition
when resources not present in adequate amounts to satisfy needs of all individuals who depend on them
intraspecific competition
individuals of same species compete for food so those best adapted obtain, survive, reproduce so slows pop. growth, entering stationary phase
interspecific competition
affects both pop. size of different species and distribution within ecosystem
as intensity of competition increases…
rate of repro. decreases but DR increase as fewer organisms have resources
why doesn’t the competitive exclusion principle always apply in natural ecosystems
environmental conditions always changing so will be a variety of limiting factors with differing strength —> pop. growth vary too much to conclude one species grows in one place
preservation
keeping species/habitats as they are now by keeping things natural and eliminating any human effects on ecosystems that exist today
conservation
more active management process involving human intervention, maintaining/improving biodiversity (also genetic diversity) and range of habitats/ecosystems
threats to biodiversity
over-exploitation for food/sport/commerce
intensive agri/increased pollution/widespread building –> habitat destruction
species introduced–> outcompete native species
effects on community when deciding conservation strategies
social/economic costs to local community, effective education/liason with community
examples of conservation strategies
extra food to raise carrying capacity, control predators/poachers, vaccinate, restrict succession, dispersal corridors
ethical reasons for conservation
species has value, human responsibility, arguments in favour of human activities are objective/driven by economics
economic/social reasons for conservation
genetic diversity need in future to breed resistance etc, food source, predators act as biological control agents, ecotourism
small scale methods of managing timber production
coppicing, pollarding, rotational coppicing, standards
large scale methods of managing timber production
felling, selective cutting, sustainable management (planting)
issues associated with felling large areas of trees
destroy habitats, reduce soil mineral levels, soil susceptible to erosion, not remove water/stop washing into waterways, not maintain levels through carbon/nitrogen cycles
