Biodiversity

Species: a group of organisms whose members are similar to ach other in shape , physiology, biochemistry and behavior and can be interbreed to produce fertile offspring.

Habitat: the place where an organisms lives includng non living factors aswell. each habitat occupied by a range of species. Species are adapted to live in a particular habitat: eg: earthwomrs live in soil.

Biodiversity: the number and variety of species to be found in the world, the genes they carry and the habitatas in which they live. Biodiversity depends on: the variety of habitats the difference between the species in the habitat and the genetic differences between indivduals within a species.

Measuring biodiversity: Sampling: meausre the biodiversity of a habitat the number and distribution of species has to be counted as wellas the number of indiviuals within each species. Usually just a small part of the habitat is sampled at random. species using key.

Random: is representative of habitat, no biased. Distribution of each species across the area where they are found. The abundance: of each species- how many species present.

Measuringh: Starting point should be rando, Pull the line across the habitat, all species touching the line are recorded, gives an immediate impression of what lives in the habitat. Qualitative results. (Line transect)

Abundance of species: Sampling habitatas with uniform abiotic conditionc: randomly placed frame quads, A grid plan is drawn, coordinates are assigned. 15 quads. percentage cover of plant species within the quad. Chaning abiotic conditions: steepness, ph soil, temp. Belt trasect is used: line streched across a habitat quads placed at regular intervals. Several transects should be placed parraelle mean % cover recorded

Sampling of animals: sweep nettimng: large nets are swept through the vegetation/ water the animlas caught, collected using a pooter. Animals counted before released.

Small animals: pitfall traps: small cups are buried to their rims and small animals into them. The animals are counted before being released. Flying insects are sampled using light trap.

Using sampling figures to calculate biodiversity: Meaure biodiveristy: richness and eveness has to be considered.

Species richness: the number of species present in a habitat. This is estimated in a qualitative survey using a line transect and by visual observations

Specieseveness: measure abundance of indivuls in each species. A habitat with similat numbers in each species is more even than a habitat where just a few species are in high numbers and others in low.

This is estimated in quanititive sampling using quads, meausre plan frequency.

Simpsons: is a formula used to measure teh diversity of a habitat, it considers evenessa dn richness. D=1E(n/N)2: n: number of individuals of a particular species: (%c) N: total number of all idividuals of all species.

A high value of simpsons index (near1) indicates High biodiversity. therefore more stable. A low number (near0) indicates that a few species dominate, so some enviromental factors such as disease could affect the habitat seriously.