Topic 4: Biodiversity Flashcards
Biodiversity
Variety in the living world
Local biodiversity
The variety of different species living in a small, local habitat
Global biodiversity
Variety of species on earth
Recent estimates put the number of species at 8.7 million
Where is global biodiversity greatest?
At the equator
It decreases towards the poles
Species diversity?
The number of different species and the number of individuals of each species within any one community
genetic diversity
The variety of genes (alleles) possessed by the individuals that make up any one species
Ecosystems diversity
The range of different habitats within a particular area
2 ways that biodiversity can be measured
Species richness
Index of diversity
What is species richness?
A measure of the number of different species in a community
- 2 communities may have the same number of species but the proportions of the community made up of each species may differ significantly
What is an index of diversity?
The relationship between the number of species in a community and the number of individuals in each species
It provides a number that makes it easier to compare species richness in different habitats
The larger the value, the greater species richness
Calculation for index of diversity
D= N(N-1)/sum of n(n-1)
D= index of diversity
N= no. Organisms of all species
n=no. Of organisms of each species
What are the effects of reducing biodiversity?
It reduces the variety of habitats
Reduces the variety of species
Reduces the variety of food sources
Farming practices that reduce biodiversity
Removing hedgerows
Creating monocultures
Draining wetlands
Overgrazing of land
Use of pesticides,inorganic fertilisers and herbicides
How does removing hedgerows benefit farmers but reduce biodiversity?
Increased farmland
Reduces species habitats
What is the impact on biodiversity of crop monocultures?
Reduces plant biodiversity which affects food webs
Conservation measure to minimise the effects of hedgerow removal
Maintains existing hedgerows to the most beneficial height
Plant hedges rather than using fences
Conservation measures to minimise the effects of monocultures on biodiversity
Create natural meadows
Conservation measures to minimise the effects of draining wetlands on biodiversity
Maintain existing ponds or create new ones
Leave wet corners of fields
Conservation measures to minimise the effects of pesticides on biodiversity
Use biological control or let wildflowers grow at the field edge as habitats for insect predators
Conservation measures to minimise the effects of inorganic fertilisers on biodiversity
Use organic fertilisers
Use crop rotation with a nitrogen fixing crop to improve soil fertility
Conservation measures to minimise the effects of herbicides on biodiversity
Use intercropping (growing 2 crops at once so you dont leave bare soil)
Rather than using herbicides to control weeds
