Resilience concerns the ability of a living system to adjust to climate change, moderate potential damages, take advantage of opportunities, or cope with consequences; in short, the capacity to adapt. The Nature Conservancy’s resilience analysis develops an approach to conserve biological diversity while allowing species and communities to rearrange in response to a continually changing climate. - See more at: http://nature.org/TNCResilience
Eastern Division scientists analyzed 393 million acres of land for resilience, stretching from Florida to Maine and adjacent areas of Canada (NOTE - The dataset included in the download was clipped to the Northeast (Region 5), for the original data see: https://nalcc.databasin.org/datasets/c57ec56be4524d81af3491747c865d29). Scientists considered individual landscapes such as forests, wetlands, and mountain ranges as collections of neighborhoods where plants and animals reside. Areas with the most complex neighborhoods in terms of topography, elevation ranges, and wetland density were estimated to offer the greatest potential for plant and animal species to “move down the block” and find new homes as climate change alters their traditional neighborhoods. The resilience study also considered the permeability of landscapes, analyzing where roads, dams, development, or other fragmenting features create barriers that prevent plants and animals from moving into new neighborhoods.
A particularly useful feature of the wall-to-wall permeability results is that they reveal basic patterns in current flow that reflect how the human modified landscape is spatially configured. Thus you can identify where population movements and potential range shifts may become concentrated or where they are well dispersed, and it is possbile to quantify the importance of a area by measuring how much flow passes through it, and how concentrated that flow is. The results can be used to identify important pinch points where movements are predicted to concentrate, or diffuse intact areas that allow for more random movements.
The four prevalent flow types each suggest different conservation strategies:
-
Diffuse flow: areas that are extremely intact and consequently facilitate high levels of dispersed flow that spreads out to follow many different and alternative pathways. The conservation strategy is to keep these areas intact and prevent the flow from becoming concentrated. This might be achievable through land management or broad scale conservation easements.
-
Concentrated flow: areas where large quantities of flow are concentrated through a narrow area. Because of their importance in maintaining flow across a larger network these pinch points are good candidates for land conservation.
-
Constrained flow: areas of low flow that is neither concentrated nor fully blocked but instead moves across the landscape in a weak reticulated network. These areas present large conservation challenges as it is not clear what the best strategy is. In some cases restoring a riparian network might end up concentrating the flow and creating a linkage that will be easier to maintain over time.
-
Blocked/Low flow: areas where little flow gets through and is consequently deflected around these features. Some of these might be important restoration areas where restoring native vegetation or altering road infrastructure might reconnect a historic connection.
To create a categorical classification of flow patterns we first converted the raster data into points and then ran a point density function on a small neighborhood (1000 acres) to calculate the flow density in the local neighborhood. Then the wall to wall grid results were compared to the neighborhood results to pull out areas where the current flow was significantly different or similar. Areas that were different from their neighborhood and had high flow were classified as concentrated flow. Areas that were different from their neighborhood and had low to medium flow were classified as constrained flow. Areas that were similar to their neighborhood and had flow were classified as diffuse flow.
For simplification of display and ease of understanding, the original six categories of flow were collapsed into four, by merging the concentrated flow categories, and the two top diffuse flow categories. This can assist the user in seeing the patterns more clearly on the landscap without needing to interpret gradations of flow. All the detailed information is still contained within the data sets - this is just simplified symbology.
