Identification of organisms
Organisms in an ecosystem can be identified using a variety of tools like dichotomous keys. A dichotomous key is organized in steps, where each step asks a question about a specific characteristic (e.g., leaf shape, body structure), leading the user to the next step or directly to the organism's identification.
Sampling strategy
Sampling strategies may be used to measure biotic and abiotic factors and their change in space, along an environmental gradient, over time, through succession, or before and after a human impact.
Quadrat sampling
Quadrant sampling is a method used to estimate the abundance and distribution of non-motile organisms (e.g., plants, and fungi) within a defined area. A quadrat is a square frame (usually 1m x 1m) placed randomly or systematically on the ground. It is simple, cost-effective, and non-invasive and provides quantitative data for ecological studies. But, this method is limited to non-motile or slow-moving organisms.
Lincoln Index
Lincoln Index is a method used to estimate the population size of motile organisms using a capture–mark–recapture technique.
This method is effective for estimating populations of mobile species and is minimally invasive when done correctly. However, it assumes marked individuals mix evenly back into the population. The accuracy decreases with small or highly mobile populations.
Formula: (M x N)/ R
Where M is the number of individuals caught and marked the first time, N is the total number of individuals recaptured and R is the number of marked individuals recaptured
Species richness and diversity
Species richness is the number of species in a community and is a useful comparative measure. Species diversity is a function of the number of species and their relative abundance and can be compared using an index. Simpson diversity index is a tool used to measure the diversity of a community by considering both the number of species (species richness) and their relative abundance (species evenness).
