3.4.6 Biodiversity Within a Community Flashcards
What do farmers do that reduces the genetic variety of alleles?
They select species for particular qualities that make them more productive
Most of a farmers area is taken up by desirable species which means that other species have to compete for remaining resources which will reduce their numbers or cause them to go extinct
Why do pesticides reduce the diversity index?
They exclude those species that compete with the farmed species for food, light, mineral ions and water
This reduces the diversity index
What practises reduce biodiversity?
Removal of hedgerows and woodland
Creating monocultures e.g replacing a field with one crop
Filling in ponds and draining marsh/wetland
Over-grazing of land e.g upland areas by sheep which prevents regeneration
Use of pesticides and inorganic fertilisers
What are the main conservation techniques?
Use hedges over fences as field boundaries
Maintain existing ponds and create new ones
Plant native trees on land with a low species diversity
Reduce pesticide use
Use organic fertilisers
Introduce conservation headlands- free of pesticides to aid wildlife
How has the government encouraged conservation efforts?
Conservation methods make food more expensive so financial incentives have been put in place
How do you calculate the means of grouped or tallied data?
Sum of fx -------------------------------- Number of data values f = frequency, x = data value When x is a range, use the midpoint
What is the individual?
One member of the population
What is a population?
Members of the same species living in the same area
What is a community?
Populations that live together in a defined area
What is an ecosystem?
A community plus it’s non-living surroundings
What is a biosphere?
All of the ecosystems on Earth
What is a habitat?
The place where an organism lives
What is the equation for the diversity index?
N(N - 1) ------------------- Sum of n(n - 1) N = total number of all organisms n = total number of each different species
What are the limiting factors in aquatic environments?
Salinity
Dissolved oxygen content
Light
Temperature
