Читать книгу Practical Field Ecology - C. Philip Wheater - Страница 19

In studies examining species richness, you might be interested in the presence or absence of one or more species (or other taxonomic group) in order to investigate the links between such species and aspects of the environment; for example, in terms of the ecology of the species concerned, or in studies of pollution where the species may be useful as a biological indicator of certain toxins. Here, simply listing the plants and animals present may suffice. Although this may appear to be a quite simple approach, care needs to be taken to ensure that sampling techniques are used that are appropriate to both the organisms under consideration and the habitats in which they are found. For example, studies on bird species richness in urban parks may be complicated if some parks are dominated by relatively open habitats of amenity grassland and formal flower gardens, whilst others feature dense shrubberies and even woodland. Observations of the species present may be easier in the open habitats than under dense canopy. Care will thus be needed to ensure that all species are counted (as accurately as possible) using the most appropriate method for that site or habitat type. For these reasons, issues around surveying habitats and sampling organisms are considered in the next three chapters.