Biodiversity

Biodiversity is a shortened form of the term “biological diversity”. Simply stated, it is the entire spectrum of life forms and the many ecological processes that support them. Biodiversity occurs at four interacting levels: genetic diversity, species diversity, community diversity and ecosystem diversity.

Wisconsin is blessed with abundant biodiversity. Located at the junction of three of North America's six biotic provinces - the eastern deciduous forest, the northern boreal forest, and the temperate grasslands - we have a wealth of species and natural communities. Approximately 1,800 species of native plants and 657 species of native vertebrates have been identified in Wisconsin. In addition, there are thousands of species of nonvascular plants and invertebrates. The challenge is to manage this diversity to conserve Wisconsin's biological heritage and preserve future management options.

In 1995, the Wisconsin Department of Natural Resources (DNR) released a report "Wisconsin's Biodiversity as a Management Issue". The report presents a Department strategy for the conservation of biological diversity. It provides DNR employees with an overview of the issues associated with biodiversity and provides a common point of reference for incorporating the conservation of biodiversity into our management framework.

Four Interacting Levels of Biodiversity

Genetic diversity is the spectrum of genetic material carried by all the individuals of a particular species. Genetic diversity within a population of a plant or animal species has the potential to change over time, allowing species to adapt to environmental conditions and retain vigor. Although genetic diversity may be expressed in visible characteristics, such as color, size, and shape, much is expressed in biochemical processes that are hidden from view. Individuals within a population carry a variety of genes. If something happens to reduce the size or variety of the gene pool, then that populations' genetic diversity is compromised.

Species diversity is the variety of species in a geographic area, including not only the number of species but also their relative abundance and spatial distribution. Species are the more familiar level of diversity because they can be classified and counted, and many though not all, are readily visible. Species include everything from soil fungi and insects to eagles and deer, from darters to muskies, and from mosses and lichens to hemlock and red pine. Every species has a niche, or a role it plays in a natural community, defined by how individuals of a species carry out their activities, use resources, and occupy space. Understanding the niche of a single plant or animal species requires in-depth study as well as an understanding of the environment in which the species lives and interacts.

A community is an assemblage of species, living together in a particular area at a particular time. Communities usually bear the name of their dominant plant species, for example, pine barrens, sedge meadows, and cedar glades. However, the community includes all of the plants living in association with the dominant species plus all of the animals present at a given time. Communities area often perceived as static, but they are actually in a constant state of change – change usually occurs, however, at a rate too slow from humans to note in our brief lifetimes.
Communities range in size from less than an acre (e.g., shaded cliff) to thousands of acres (e.g., mesic hardwood forest). The diversity of a given community is determined by the variety of type of species present, the intricacies of their interactions, and the age and stability of the community.

An ecosystem includes not only biological communities but also the myriad, continuing interactions of biological communities with their abiotic (non-living) environment, including moisture, temperature, sunlight, soil, and many other physical and chemical factors. Ecosystems, which range in size from minute to millions of acres, exhibit complex linkages among plants, animals and the physical and chemical environments. Ecosystem diversity is largely determined by the amount and complexity of these linkages. Ecosystems, like biological communities, are in a constant state of change, called “ecological succession.” Succession is the progressive change through time of species composition, organic structure, and energy flows throughout an ecosystem. Ecosystems are constantly changing in response to short-term human impacts such as timber harvest and naturally caused perturbations such as fire or disease, along with long-term influences such as climatic change. Ecosystems are in turn part of the larger landscape of adjacent and interacting ecosystems. Surrounding lands can significantly affect the character of an ecosystem; therefore, ecosystems must be considered within the context of the broader landscape.

For more information on this topic see Wisconsin's Biodiversity as a Management Issue Report pp. 10-12 [PDF 470KB].