🩶 3.4 Topic 4 - 3.4.6 Biodiversity within a community Flashcards
give a definition for biodiversity
the number and variety of living organisms in a particular area.
give a definition for habitat
the place where an organism lives.
give a definition for community
all the populations of different species in a habitat.
give a definition for a species
a group of similar organisms which are able reproduce to give fertile offspring.
what does it mean if areas have high biodiversity?
that there are lots of different species.
what are the two levels biodiversity can be considered at?
Local and global.
give a definition for local biodiversity
variety of different species living in a small habitat that’s local to you.
give a definition for global biodiversity
variety of different species on earth.
what 3 components [beginning with S, G and E] does biodiversity have?
species diversity, genetic diversity and ecosystem diversity.
what does species diversity refer to?
refers to the number of different species and the number of individuals of each species within any one community.
what does genetic diversity refer to?
refers to the variety of genes possessed by the individuals that make up a population of a species.
what does ecosystem diversity refer to?
refers to the range of different habitats, from a small local habitat to the whole of the earth.
what is the measure of species diversity called?
species richness.
give a definition for species richness
a measure of the number of different species in a community.
what does an index of diversity describe?
the relationship between the number of species in a community (species richness) and the number of individuals in each species.
give the index of diversity formula
d = N (N- 1) / £n(n - 1)
what does the N in the index of diversity formula mean?
total number of organisms of all species.
what does the n in the index of diversity formula mean?
total number of organisms of each species.
what does the £ in the index of diversity formula mean?
the sum of.
The number of species in a community and the abundance of each species is also known as the …
… species diversity
what does a high value of the index of diversity mean?
the species diversity is high.
If all the individuals are of the same species (no biodiversity), what is the index of diversity?
1.
what techniques reduce biodiversity?
farming and agriculture.
what do natural ecosystems become after developing over time?
complex communities with many individuals of a large number of different species – these communities have a high index of diversity.
what happens to the number of species when farmers select species for particular qualities that make them more productive?
the number of species, and the genetic variety of allele they possess is reduced to the few which exhibit the desired features.
list 4 ways agricultural practices can reduce biodiversity:
monoculture, deforestation(woodland clearance), hedgerow removal, pesticides and herbicides.
how do monocultures reduce biodiversity?
+ when crops are grown on a large scale for agriculture, a single crop (a monoculture) species covers many fields.
- monocultures directly remove species and fewer species can survive in monoculture environments.
how does deforestation/woodland clearance reduce biodiversity?
+ large regions of forests are cleared to provide space for farming.
+ forests are biodiverse environments because there are many different habitats for different species.
- direct removal of species and removal of habitats causing species to die.
how does hedgerow removal reduce biodiversity?
+ done to increase farmland by turning lots of small fields into fewer large fields.
how do pesticides reduce biodiversity?
+ pesticides are sprayed onto crops to prevent pests e.g. slugs from feeding on crops.
- direct removal of pests and species that feed on the pests cannot survive as lose a food source.
how do herbicides reduce biodiversity?
+ herbicides are sprayed onto crops to prevent growth of unwanted plants and weeds.
- direct removal of plants and species that feed on unwanted plants cannot survive.
what schemes can help avoid the impacts of agriculture?
conservation schemes.
how do conservation schemes help avoid the impacts of agriculture?
: endangered species can be legally protected to avoid extinction.
: specific areas with high biodiversity can be protected (cannot be developed into farmland).
: farmers are encouraged to balance agriculture with conserving biodiversity.
What are 3 examples of conservation schemes?
Giving legal protection to endangered species.
Creating protected area such as SSSIs (Sites of Special Scientific Interest) and AONBs (Areas of Outstanding Natural Beauty). These restrict further development, including agricultural development.
The Environmental Stewardship Scheme which encourages farmers to conserve biodiversity e.g. by replanting hedgerows and leaving margins around fields for wild flowers to grow.
what are 4 direct removals of habitats, reducing species diversity?
> removing hedgerows and grubbing out woodland.
creating monocultures, for example replacing natural meadows with cereal crops or grass for silage.
filling in ponds and draining marsh and other wetland.
over-grazing of land, for example, upland areas by sheep, thereby preventing regeneration of woodland.
what are 3 indirect removals of habitats, reducing species diversity?
< use of pesticides and inorganic fertilisers.
< escape of effluent from silage stores and slurry tanks into water courses.
< absence of crop rotation and lack of intercropping or undersowing.
what happens if biodiversity is reduced?
the global living system becomes increasingly unstable and we all rely on the global system for food and other resources.
what two things need to be balanced so we don’t lose too much biodiversity?
agriculture and conservation.
