10.3 - Species diversity and human activity Flashcards
what is a population
A group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed.
what is a community
all the living organisms present in an ecosystem at a given time
what is abundance
the number of individuals within a species
what is a habitat
the place where an organism normally lives and which is characterised by physical conditions and the types of other organisms present
what is species
a group of similar organisms that can breed together to produce fertile offspring
what is biodiversity
the range and variety of genes, species, and habitats within a particular region
what is abiotic
an ecological factor that makes up part of the non-biological environment of an organism (e.g. temp, pH, rainfall, humidity, etc)
describe what an agricultural ecosystem is, and how it’s related to genetic diversity
- controlled by humans and are different
- farmers create these in order to select species for particular qualities that make them more productive
- as a result, the number of species (and the genetic variety of alleles they posses) is reduced to few = in order to exhibit the desired features
how do agricultural ecosystems having large quantities of 1 species leads to reduced species diversity
- to be economic = numbers of the desired species needs to be large
- this is because any area can only support a certain amount of biomass
- if this area is taken up by the desired species = smaller area available for other species
- these species then need to compete for what limited resources are there = many don’t survive this competition (regardless of if they evolve because the population would still be reduced)
how do agricultural ecosystems using pesticides reduce species diversity
- pesticides are used to exclude any other species present that the farmer doesn’t want
- because these unwanted species will compete for the light, mineral ions, water and food that the farmed species wants
- therefore the pesticides reduce species diversity
is the index of species diversity high or low
low
describe the balance between conservation and farming
- food is essential for an ever-expanding human population
- because it’s expanding = increasing pressures to produce more
- this is achieved via:
1) improved genetic varieties of plant and animal species
2) greater use of chemical fertilisers and fertilisers
3) uses of biotechnology
4) changes in farming practise (leading to larger farms)
–> overriding ecological impact of this = diminished variety of habitats within ecosystems = reduction in species diversity
what are some of the practises that have directly removed habitats and reduced species diversity
- Removal of hedgerows and grubbing out woodland
- creating monocultures (e.g. replacing natural meadows with cereal crops)
- filling in ponds and draining marsh/other wetland
- over-grazing of land (e.g. upland areas by sheep, thereby preventing regeneration of woodland)
what are some of the practises that have indirectly removed habitats and reduced 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 under sowing
what are some of the advantages of management techniques
- increase species and habitat diversity
- whilst not raising food costs or lowing yields
what are some of the management techniques in order to promote species diversity and habitat diversity
- maintain existing hedgerows at the most beneficial height and shape (e.g. an A shape rather than a square shape)
- Plant hedges rather than erect fences as field boundaries
- maintain existing ponds and (where possible) create new ones
- leave wet corners of fields instead of draining them
- plant native trees on land with a low species diversity rather than in species-rich areas
- reduce the use of pesticides (use biological control where possible or genetically modified organisms that are resistant to pests)
- use organic, rather than inorganic fertilisers
- use crop rotation that includes a nitrogen-fixing crop, rather than fertilisers, to improve soil fertility
- use intercropping rather than herbicides to control weeds and other pests
- create natural meadows and use hay rather than grasses for silage
- leave the cutting of verges and field edges until after flowering and when seeds have dispersed
- introduce conservation headlands (areas at the edges of fields where pesticides are used restrictively so that wild flowers and insects can breed
what are the disadvantages of some conservation techniques, how is this countered?
- makes food slightly more expensive to produce
counter: - encourage farmers that there a number of financial incentives from the DEFRA and the European Union
