How ELUs Can Guide Conservation





1. What Drives Biodiversity?

Plant and Animal Diversity
Many factors determine which species of plants and animals live in an area.  For animals, the variety and species of plants in an area are important components of “habitat.”  For plants, the physical properties of a site frequently determine the suitability of the area for supporting specific species.  Critical physical properties are elevation, slope, aspect, geology, soils, and hydrology.  For example, some species of plants (e.g., pitch pines) thrive in gravelly, well-drained soils, in dry landscapes; whereas, other species, such as red maple, prefer moist, highly organic soils in poorly-drained locations.  The land use and disturbance history of a site are also very important and can, in some cases, be the most important factors determining the richness of biodiversity. This is most true when land use destroys habitat, alters hydrology, or replaces natural vegetation with impervious surfaces.

Physical Diversity Begets Biodiversity
Research by many scientists have shown that there is a strong positive relationship between the diversity of physical characteristics on the landscape and the variety of plants that occur there.  This relationship occurs at site-level scales (5 acre study plots) and larger landscape scales (tens and hundreds of acres). Recently, scientists from The Nature Conservancy showed the same relationship across states in the eastern United States.  In that study, over 90% of the variation in plant and animal variety could be explained by the diversity of geological and topographic settings in a state.

Physical Diversity and Conservation
The relationship between physical diversity and ecological diversity has important relevance to the conservation community – protected lands that are highly variable with respect to physical properties will likely support diverse communities of plants and animals as climate changes.  It is difficult to know which species will occur at a specific location many decades into the future, but landscapes that contain many different physical characteristics will contain diverse assemblages of plants (and therefore animals) that are best suited for those specific conditions.  Therefore, the identification of areas on the landscape that are physically diverse might be important targets for conservationists because they are likely to support high biodiversity as climactic conditions change.

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