populations and sustainability Flashcards
what is a population?
the number of individuals of the same species in a particular area
describe the stages in a population graph
lag phase -> log phase -> carrying capacity -> death phase
what shape is the population growth curve?
s shape
what is the lag phase?
only few individuals, still acclimitising to their habitat. initial small population size means few births. growth in pop. size is slow
what is the log phase?
plenty of resources, optimal conditions. rate of reproduction exceeds death rate and pop. growth is rapid
what is carrying capacity?
stationary phase where habitat cannot support larger population. reproduction rate and death rate are equal
what is the death phase?
when death rate exceeds birth rate
what are limiting factors?
factors that limit the growth in population size
what are density dependent limiting factor examples?
availability of resources, parasitism, disease, predation and competition. acts mores strongly as size increases
what are density independent limiting factor examples?
temperature changes, earthquakes, fires. act strongly irrespective of population size
what are k strategists?
species that have population sizes determined by carrying capacity. limiting factors exert increasingly significant effect as pop. size reaches carrying capacity (e.g. birds,animals)
what are some characteristics for k strategists?
long lifespan, late reproductive age, slow development, larger body mass, low reproductive rate
what are r strategists?
species in which the population size increases so quickly that it can exceed the carrying capacity before limiting factors start to have an effect
what are some characteristics for r strategists?
short lifespan, small body mass, high reproductive rate, quick development, young reproductive age
describe the population growth graph for r strategists
once carrying capacity exceed -> death phase of boom -> bust
could be due to resources running out
are predators or prey always smaller in number on predator-prey graph
predators
what are the types of competition?
intraspecific and interspecific
what is the competitive exclusion principle?
2 species cannot occupy the same niche
what is a case study of interspecific competition?
P.aurelia and P.caudatum have an overlap in the niche so more intense competition. P.caudatim dies out due to comp. and is outcompeted for food
what is conservation?
humans actively managing a resource, habitat or ecosystem o maintain or restore biodiversity
what is preservation?
the resource of habitat is left untouched by humans. this can mean that the ecosystem changes over time (succession)
what are sustainable methods of small scale timber production?
coppicing (where tree trunks cut close to ground so new shoots form from cut surface and mature). rotational coppicing. pollarding (trunk cut higher up than coppicing)
what are sustainable methods of large scale timber production?
selective cutting (removing largest trees). replace trees through replanting rather than waiting for natural regeneration. plant trees far enough from each other. manage pests and pathogens. ensure areas of forest remain for indigenous ppl
what are sustainable methods for fishing?
international agreements, fishing quotas, using nets of different mesh sizes, allowing commerical and recreational fishing only at certain times of the year, reintroducing fish farming to maintain the supply of protein food & preventing the loss of wild species
case study: terai region of nepal
problem -> overgrazing, over exploitation of forest, expansion of agriculture into forested areas
solution -> employment for sustainable jobs, conservation of areas has spread, improve soil & water management
case study: masai mara
problem -> poachers for elephants, overgrazing, overcultivation
ecotourism -> support conservation, no exploitation
research -> employment of reserve rangers, provision of communication equipment, has helped lion, buffalo etc
case study: galapagos islands
methods to reduce human activity -> limiting area tourist, controlling livestock movement, introducing anti poaching measures, replanting forests, limiting hunting (quotas) galapagos national park -> park rangers, strict control
case study: antartica
1961 antarctic treaty -> signed by 12 countries, nuclear explosives banned, disposal of radioactive waste
effect of human activity -> global warming, hunting of whales and seals, soil contamination, discharge of waste into seas
case study: uk conservation
snowdonia national park -> conserve natural beauty in park
lake district -> regions of moorland. wide range of wildlife. replanting native tree species
