Sampling methods

Purpose There is not enough time to count every organisms within an area or population. Assume sample is representative of the whole. Need to use a standard sampling method.

Lincoln Index – capture-mark-release-recapture 2.3.2 Describe and evaluate methods for estimating abundance of organisms Lincoln Index – capture-mark-release-recapture It is essential that the marking is non-harmful, and non-conspicuous. Movement of animals into and out of your sample area will give bad results.

2.3.2 Describe and evaluate methods for estimating abundance of organisms Quadrats- Used for non-mobile organisms. Vary from .25 to 1 m squares Select quadrant size by finding smallest quadrant that has the largest diversity Used to calculate population density – individuals of each species per unit area. Plant coverage determined through percentage coverage.

2.3.2 Describe and evaluate methods for estimating abundance of organisms If habitat is same throughout use, random grid. If the habitat varies, get equal samples from each type. If there is an environmental gradient, then place quadrats at set distances. Percentage frequency – how many quadrats a species is in.

Samples are dried to a constant weight to remove water. 2.3.3 Describe and evaluate methods for estimating the biomass of trophic levels in a community Samples are dried to a constant weight to remove water. For plants you would take all the samples from a quadrat, and then multiply by the total number of quadrats. Stated per unit area.