The term 'biodiversity mapping' encompasses a variety of techniques used to represent and analyze patterns of biodiversity, and is almost always used within the framework of environmental conservation. Although maps of biodiversity can be useful simply as a way to represent complex environmental data in an easily interpretable form, usually biodiversity mapping involves further analysis and manipulation of the data in order to answer specific conservation questions. Out of necessity, some areas must be prioritized over others in terms of their conservation value. Until recently, this was done on a largely ad hoc basis with ecosystems receiving protection largely because of dramatic landscapes, recreational value, or the absence of alternative economic uses of the landscape. Over the past two decades, however, there has been a growing effort to protect important landscapes according to scientifically rigorous criteria; biodiversity mapping has been a critical tool in this effort.
Biodiversity mapping involves the cartographic representation of species distributions and/or other environmental characteristics as proxies for biodiversity. Further data, such as information on human use of the land, can also be incorporated in the analysis. These layers of data are typically entered into a geographic information system (GIS) in order to generate maps that can be used to answer the conservation questions at hand. There remain many barriers to producing useful biodiversity maps: the very notion of biodiversity is not easily quantifiable; there is a profound lack of environmental data for certain elements of ecosystems and many parts of the world, and often the quality of available data is poor. Much of the debate surrounding biodiversity mapping focuses on how to approach the problem of imperfect data and how the notion of biodiversity can best be represented. In particular, at what scale, and with what surrogate measures, can we best quantify biodiversity in ways that provide meaningful answers to conservation questions?