2.7 Quantifying connectivity properties
We identified the least-cost paths using Linkage Mapper v. 2.0.0.
(McRae and Kavanagh, 2011 ), a GIS
toolbox developed for connectivity analysis based on cost-weighted
distance surface. We used the core area (protected area) polygons and
resistance raster to perform cost-weighted distance calculations from
each protected area. As each cost-weighted distance surface is created,
Linkage Pathways also extracts minimum cost-weighted distances between
source and target core area pairs. Once the linkage zones have been
mapped using Linkage Mapper, the Centrality tools from the Linkage
Mapper toolbox were used to calculate current flow centrality across the
networks. Current flow centrality is a measure of how important a link
or core area is for keeping the overall network connected.
To identify the barrier areas and priority areas of connectivity
restoration,we used the Barrier Mapper tool from Linkage Mapper.
Barrier Mapper detects important barriers that affect the quality and/or
location of the corridors using a circular search window. Results give
expected reduction in least-cost distance per unit distance restored
assuming pixels in the window are changed to a resistance of 1.0.
Greater reductions in cost-weighted distance (i.e. increase in
connectivity) indicate areas of greater restoration potential
(McRae, 2012 ). We applied a single
moving window radius (110 km) to search. This range accounts for the
maximum dispersal capacity of North China leopard. For each pixel we
calculated the sum of connectivity improvement scores taken across all
core area pairs, highlighting areas that impede movement between
multiple pairs of conservancies.