3.4.6 Biodiversity within a community Flashcards
What is biodiversity?
The variety of all the different species of organisms in all habitats.
What range of habitats can biodiversity relate to?
From a small local habitat to the whole Earth.
Define species richness.
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 and the number of individuals in each species.
State the formula for the index of diversity.
d equals N open bracket N minus 1 close bracket divided by the sum of n open bracket n minus 1 close bracket.
In the index of diversity formula what does N represent?
Total number of organisms of all species.
In the index of diversity formula what does n represent?
Total number of organisms of each species.
How do farming techniques generally affect biodiversity?
Farming techniques reduce biodiversity.
Explain why farming reduces biodiversity.
Farming often involves removal of hedgerows monocultures use of pesticides and herbicides all of which reduce habitat variety and food sources.
How can farmers balance conservation and farming?
Farmers can maintain biodiversity by leaving margins around fields maintaining hedgerows and practicing crop rotation.
What is species richness
(A measure of) the number of (different) species in a community;
Why is calculation of index of diversity more reliable than species richness?
(Index of diversity also) measures abundance / number / population (size) of each species;
(So useful because) may be many of some species
Suggest one reason the scientists used biomass instead of the number of individuals of each plant species when collecting data to measure diversity.
Individual organisms could not be identified/separated OR Too small/numerous to count individuals
Outline a method the ecologists could have used to determine the plant species richness at one site.
- A method of selecting sampling sites at random e.g. random number generator
- Use of quadrat;
- Identify (plant) species (at site / in each quadrat)
Farming Techniques – Pros and Cons to farmer for Planting Hedges
(Pros)
- Greater (bio)diversity so increase in predators of pests
- Increase in predators of pests so more yield/income
- Increase in pollinators so more yield/income
(Cons)
- Reduced land area for crop growth/income
- Greater (bio)diversity so increase pest population
- Increase pest population so less yield/income
- Increased competition so less yield/income
Suggest one ethical argument for maintaining biodiversity.
Prevent extinction / loss of populations / reduction in populations / loss of habitats
Suggest one economic argument for maintaining biodiversity.
Medical or pharmaceutical uses of plants Tourism Agriculture Saving forest communities
