Landscape factors
A relatively recent (2009) land cover map of the BMR was used to assess
landscape functional structure in the nearby of both butterfly and bird
transects. These biodiversity databases consist in 91 transects
monitored to get data of birds (linear buffer: 500 m), and 23 transects
monitored to obtain data of butterflies (circular buffer: 750 m). In
these buffers (Fig. 2 ), a set of landscape metrics of landscape
composition and configuration were obtained using SIG (ArcGIS) methods.
Regarding landscape composition, we calculated the proportion of main
land cover categories (Forest, Scrubland, Cropland and Built-up) per
buffer. Regarding landscape configuration, we obtained landscape
heterogeneity (i.e. land cover evenness), edge density (i.e. the sum of
edge length divided by buffer area), polygon density (i.e. the amount of
patches per buffer area), largest patch index (i.e. the area percentage
of the largest patch in the buffer), effective mesh size, a
defragmentation measure proposed by Jaeger (52 ), and ecological
connectivity, inferred from the ecological connectivity index proposed
by Marull and Mallarach (53 ).