Landscape Diversity Stratified by Geophysical Setting and Ecoregion with Regional Override, 2016 Eastern U.S. and Canada
Dates
Publication Date
2016-04
Summary
A climate-resilient conservation portfolio includes sites representative of all geophysical settings selected for their landscape diversity and local connectedness. We developed methods to identify such a portfolio. First, we mapped geophysical settings across the entire study area. Second, within each geophysical setting we located sites with diverse topography that were highly connected by natural cover. Third, we compared the identified sites with the current network of conservation lands and with The Nature Conservancy’s (TNC’s) portfolio of important biodiversity sites identified based on rare species and natural community locations.Using this information we noted geophysical settings that were underrepresented in current conservation [...]
Summary
A climate-resilient conservation portfolio includes sites representative of all geophysical settings selected for their landscape diversity and local connectedness. We developed methods to identify such a portfolio. First, we mapped geophysical settings across the entire study area. Second, within each geophysical setting we located sites with diverse topography that were highly connected by natural cover. Third, we compared the identified sites with the current network of conservation lands and with The Nature Conservancy’s (TNC’s) portfolio of important biodiversity sites identified based on rare species and natural community locations.Using this information we noted geophysical settings that were underrepresented in current conservation and identified places for each setting that could serve as strongholds for diversity both now and into the future. The variety of microclimates present in a landscape, what we term the site’s landscape diversity,can be used to estimate the capacity of the site to maintain species and functions. We measured landscape diversity as a function of topography, elevation range, the density and configuration of wetlands, and soil diversity. Topography describes the natural surface features of an area, and forms local landforms such as cliffs, summits, coves, basins, and valleys. Landforms are a primary edaphic controller of species distributions, due to the variation they create in rates of erosion and deposition, in soil depth and texture, in nutrient availability, and in the distribution of moisture and temperature. Because each landform represents a local expression of solar radiation and moisture availability,a variety of landforms results in a variety of meso and micro climates. When climate change is considered, landform variation increases the persistence of species by providing many combinations of temperature and moisture within a local neighborhood, and these options buffer the resident species from the direct effects of the changing regional climate. We hypothesized that sites with a large variety of landforms and long elevation gradients will retain more species throughout a changing climate by offering ample microclimates and thus more options for rearrangement. However, we found that in areas with very little topographic diversity, we needed a finer-scale indicator of subtle micro topographic features, to distinguish between otherwise similar landscapes. We chose wetland density as a surrogate for micro-topography in flat landscapes after experimenting with several rugosity measures. Our final measure of landscape diversity was based on landform variety, elevation range, wetland density and configuration, and soil diversity.
This attribute provides the cell’s score for landscape diversity calculated using a 100 acre search area around a 30-meter cell. Landscape diversity is a measure of the variety of landforms, the elevation range, and in very flat areas: the density of wetlands. It estimates the number of micro-climates available for species. The diversity score is given as a SD category based on its standard normalized score for setting and ecoregion for the 30-meter grid. The Nature Conservancy’s Appalachian Resilience Project aimed to identify key places areas for conservation based on land characteristics that increase diversity and resilience. This is the estimated resilience score, based on the combined scores of landscape diversity and local connectedness, and ranked relative to the geophysical setting and ecoregion. The estimated resilience score is given as a SD category based on its standard normalized score for the setting and ecoregion. This is an update to Resilient Networks for Terrestrial Conservation in Eastern North America and Resilient Sites for Terrestrial Conservation in the Southeast. This data was completed in April 2016.