Biodiversity, an indicator of biological complexity, can be measured at the species level, with a catalogue of the number of types of organisms present. In order to understand the importance of biodiversity, diversity both above and below the species level must also be known. At the ecosystem level, diversity of habitat and functional types must be recognized. Within a species, long-term ecological health requires diversity at the genetic level: for instance, not only must there be a large number of beetles, but the beetles must not all be bark-borers and there must be genetic flexibility within the species, in order for the species to survive in the changes found within a natural environment.
An area with a high biodiversity has a large number of species of organisms, from microbes to mammals and flowering plants; there are many biological communities, not large tracts of a few species; and there are large numbers of individuals from different gene lines within any species. Natural communities are made up of a number of species: these species fill a number of niches or functions within the communities; and species which reproduce sexually will have genetic diversity if their populations are large enough. On the other hand, in agriculture, a field contains a single species of plant, and other species are discouraged by various practices. In Saskatchewan, this field may cover a considerable amount of land; it is the product of commercial seed in which a number of traits have been selected, resulting in reduced genetic variability. Thus, agricultural settings are characterized by very low biodiversity.
Natural communities differ in their level of biodiversity. Saskatchewan has relatively low biodiversity due to its high latitude position, the absence of mountains, the absence of an ocean coast, low precipitation, and the large scale of its landscape, resulting in only four ecozones and eleven ecoregions. Higher biodiversity is found in areas such as Peru, which is at a low latitude, benefits from the foothills and mountains of the Andes, borders on the Pacific Ocean, and has areas of high and low rainfall as well as a variable landscape. If we contrast the well-known bird faunas of the two areas, we see that Saskatchewan has 300 regularly occurring species while Peru, at only twice the area, has 1,800 species. These include a number of types of birds, such as fish-eating seabirds and fruit-eaters, which do not occur in Saskatchewan. Research has shown that areas of low biodiversity may be particularly vulnerable to species loss with the occurrence of any perturbation, such as human processes and climate change. Conservation is the process where groups and agencies attempt to maintain biodiversity at as high a level as possible, for the good health of the environment in which all the species, including humans, live.