Biodiversity is the degree of variation of life. It is a measure of the variety of organisms present in different ecosystems. It can be studied on many levels. At the highest level, you can look at all the different species on the entire Earth. On a much smaller scale, you can study biodiversity within a pond ecosystem or a neighborhood park.
Conservation biologists have designed a variety of objective means to measure biodiversity empirically. For practical conservationists, measurements should include a quantification of values that are commonly shared among locally affected organisms. More about measurment .