2.7 Connectivity analyses
We have used the universal corridor network simulator UNICOR; (Landguth,
Hand, Glassy, Cushman, & Sawaya, 2012) to create two sets of
connectivity predictions including (1) resistant kernels (Compton et
al., 2007) and (2) factorial least-cost paths (Cushman et al., 2009).
The factorial least-cost path analysis implanted in the UNICOR simulator
applies Dijkstra’s algorithm to resolve the single-source shortest path
issue from every mapped species occurrence location on a landscape to
every other occurrence location (Landguth et al., 2012). The analysis
produces the sum of predicted least-cost paths from each source point to
each destination point. The resistant kernel algorithm calculates the
cumulative resistance cost-weighted dispersal kernel around each source
point up to a user-defined dispersal threshold. As such it provides an
incidence function of the rate of organism movement through every pixel
in the landscape as a function of the density and number of source
points, the dispersal ability of the species, and the resistance of the
landscape (Compton et al., 2007). And also it produces a spatial
incidence function of the expected rate of movement of each species
through each pixel in the landscape (Cushman, Landguth, & Flather,
2013).
To account for uncertainties regarding the movement behavior of two
target species, four distance thresholds were used in the resistant
kernel analyses: 50000, 100000, 150000 and 200000 cost units, which
represent movement abilities of 50, 100, 150 and 200 km, respectively,
through optimum, low resistance habitat (Shahnaseri et al., 2019). Also,
we used the connectivity maps to identify core areas for each species.
We defined core habitat patches as contiguous patches with resistant
kernel values > 10% of the highest recorded for the
species (Ashrafzadeh et al., 2020; Cushman, Landguth, et al., 2013). We
ranked these key patches based on their strength (sum of kernel values)
and size (Cushman et al., 2018). The final ranking value for the core
areas prioritization represented the averaged values of these
sub-rankings. We quantified the extent and percentage of PAs and
corridors for each species that were within the current conservation
network to evaluate the effectiveness of the current conservation
network in providing connectivity for these species in Iran. We also,
intersected the predicted core habitats and corridor path of both study
species to identify important areas to both species.