3.4.6 biodiversity within a community Flashcards
what is biodiversity?
the number and variety of living organisms in an area
what are the 3 types of biodiversity?
species diversity = the number of different species and individuals within a community
genetic diversity = the variety of genes within a population of a species
ecosystem diversity = the whole range of different habitats on all scales
how can species diversity be measured?
can be measured using species richness
species richness = the number of different species in a particular area at a particular time
what is the equation for index of diversity?
EQUATION
d = N ( N − 1 )
Σ n (n − 1)
importance of species diversity
can be used to measure the health of an ecosystem
the higher the species diversity index the more stable an ecosystem is likely to be
why? more different species allows more species to tolerate a change in the environment
describe the impact of agriculture on biodiversity
don’t want biodiversity with agriculture
agriculture reduces species biodiversity
natural ecosystems usually develop into complex communities with lots of different species
ecosystems associated with agriculture are associated with humans and reduced to a few species
less species and alleles
less species = each area can only support a limited amount of biomass - less species, less variety and genetic diversity
less alleles within a species = species are often selected based on desirable characteristics to make farming more productive, so results in less genetic variation
harmful farming products
directly
removing hedgerows:
+ better financially for farmers
+ easier to crop and graze large fields
- important for biodiversity
overgrazing:
- using cattle to eat grass right down
- prevents biodiversity
creating monocultures:
+ field of certain crops
- reducing biodiversity
harmful farming products
indirectly
use of pesticides + inorganic fertilisers
+ better yield of crop
+ no competition between weeds + crops
effluent runoff into water:
- sewage runoff
not rotating crops:
+ puts nitrogen back into soil every 2 years
why do we use conservation techniques to maintain biodiversity?
help increase diversity without significantly raising food costs or lowering yields
in practice, it is recognised as the conservation of species diversity which will increase the production costs of food
to combat the department for environmental food and rural affairs (DEFRA) and the EU provide financial incentives to assist the use of techniques to maintain biodiversity
examples = set aside ( a gap between hedge and crop) and financial incentives
why do we maintain hedgerows at a beneficial height and shape?
provides vital resources for mammals, birds and insect species
acts as wildlife corridors allowing dispersal between isolated habitats
why do we reduce the use of pesticides?
prevent destruction of beneficial insect populations that act as natural enemies of pests
increase nutritional value of food
protects biodiversity and increases species richness
reduces death rate and prevents contamination in soil and water
why do we plant hedges instead of using fences?
provide a form of shelter, providing forging opportunities for faunal protected species such as dormouse
why do we maintain ponds or create them?
provide important freshwater habitats, supporting both species restricted to ponds
why don’t we drain wet corners or fields?
huge attraction to wildlife and provides habitats
