Читать книгу Practical Field Ecology - C. Philip Wheater - Страница 21

Another type of study of interest would be to establish the structure of the community of a specified area or habitat type (e.g. the community of fish in a lake, or the community of insects inhabiting a certain species of tree). Such studies may involve sampling a large range of quite different organisms. Organisms differ in size, distribution (both spatially and temporally), their use of microhabitats and, in the case of many animals, mobility. As such, care needs to be taken to ensure that the methods are as comprehensive as possible and are not biased towards or against any particular species or groups of species. For example, sieving soil to examine the communities of animals living within different layers (leaf litter, humus layer, the ‘A’ horizon of the soil, etc.) may underestimate larger animals that are found at low densities (e.g. large ground beetles), and may overestimate species that are found in large aggregations if sampling happens to coincide with these groupings (e.g. some woodlice). Several different techniques may need to be used together during a single study in order to obtain a broad understanding of the community structure of such habitats.