This page provides links to several datasets that were generated for and presented in Littlefield et al. 2017, a paper entitled "Connecting today's climates to future analogs to facilitate species movement under climate change" (full citation below). These datasets represent potential movement routes of organisms which will need to shift their range in response to climate change. Conserving the areas which hold a high number of potential movement routes can help facilitate these range shifts and thus reduce loss of biodiversity as climate changes.

Increasing connectivity is an important strategy for facilitating species range shifts and maintaining biodiversity in the face of climate change. To date, however, few studies have included future climate projections in efforts to prioritize areas for increasing connectivity. The data linked below identifies key areas likely to facilitate climate-induced species movement across western North America. Using historical climate datasets and future climate projections, the researchers mapped potential routes between current climates and their future analogs with a novel moving-window analysis based on electrical circuit theory. In addition to tracing shifting climates, the approach accounts for landscape permeability and empirically-derived species dispersal capabilities. The researchers compared connectivity maps generated with the new climate-change informed approach to maps of connectivity based solely on the degree of human modification of the landscape. The results show that including future climate projections in connectivity models substantially shifts and constrains priority areas for movement to a smaller proportion of the landscape than when climate projections are not considered. Potential movement, measured as current flow, decreases in all ecoregions when climate projections are included, particularly when dispersal is limited, making climate analogs inaccessible. The results illustrate that movement routes needed to track changing climatic conditions may differ from those that connect present-day landscapes, and that incorporating future climate projections into connectivity modeling is an important step towards facilitating successful species movement and population persistence in a changing climate.

The new connectivity analysis approach, called Omniscape, was developed based on Circuitscape, one of the most widely-used software packages for connectivity analysis. More information on Omniscape can be found here.

 

Figure 2. Potential movement in Washington State (a) between climate analogs without considering human modification (i.e., a uniform resistance value of 1 was applied across the study area and there was no naturalness criteria for climate analogs); (b) across a human-modified landscape but not including climate analogs (i.e., within a given moving window, Circuitscape injects current from all natural cells—not only matching climate analogs—that may then flow to the central target cell); and (c) between climate analogs across a human-modified landscape (as per methods described in the text). The connectivity impact of climate projections (d) was computed by normalizing and then taking the difference between potential movement that does not (b) and does (c) link climate analogs: red areas in (d) are important for climate-induced movements whereas green areas emerge as important for connectivity when climate change is not considered. Sources and targets for connectivity (i.e., climate analogs) were constrained to only the most natural areas, except in (a). The color ramp of (a), (b), and (c) reflects the low (blue) and high (yellow) values of potential movement for each frame. Thus, the colors are not directly comparable across frames, and results should be interpreted with regards to relative importance of specific areas for potential movement. Analogous climates were defined for the historical time period and the 2080s using MIROC5 projections under RCP 8.5, and a dispersal rate of 0.5 km/yr was used. The channeled scablands of southeastern Washington, referenced in the text, are circled in (b).

Figure 3. Potential movement in two time steps versus one and for two different dispersal capacities across a human-modified landscape. (a) and (b): potential movement between climate analogs from the historic-2050s period; (c) and (d): potential movement between climate analogs from the subsequent 2050s-2080s period; and (e) and (f): potential movement between climate analogs from the historic-2080s period (i.e., one extended time step). Panels on the left reflect dispersal capacities of 0.5 km/yr, and panels on the right reflect dispersal capacities of 5 km/yr. Analogous climates were defined using MIROC5 projections under RCP 8.5. Sources and targets for connectivity (i.e., climate analogs) were constrained to only the most natural areas. The color ramp reflects the low (blue) and high (yellow) values of potential movement for each frame. Thus, the colors are not directly comparable across frames, and results should be interpreted with regards to relative importance of specific areas for potential movement. The western-most foothills of the Cascades, referenced in the text, are circled in (a).

Data

Each archive provides results relevant to one of 3 general circulation models (GCMs) that were chosen to be representative of variation within a broader group of GCMs: a) INM CM4 (Volodin et al. 2010), which projects low levels of climate change for the study area; b) MIROC5 (Watanabe et al. 2010), which projects moderate change; and c) GFDL CM3 (Donner et al. 2011), which projects considerable change. There are 3 gridded products contained in each of the 3 GCM files linked below:

a) Flow including climate and including resistance, scaled from 0-1;
b) Flow not including climate and including resistance, scaled from 0-1;
c) Connectivity impact of including climate projections. Flow not including climate was subtracted from flow including climate.

Relevant parameters/values used throughout (unless otherwise noted) are:

1. RCP - RCP8.5 (high emissions scenario).
2. Time period: historical (1961-1990) to "2080s" (2071-2100) analogs.
3. Dispersal rate - 0.5 km/year.
4. Resistance values were squared where included.
5. Climate analog threshold was 0.9 PCA units.

This data has been prepared for the AdaptWest project and its development was funded by the Wilburforce Foundation. All input climate datasets can be obtained from AdaptWest.