Habitat heterogeneity diversity: A simple animal biodiversity surrogate in Spain

The lack of wall-to-wall biotic inventories poses a significant challenge for conservation biology. Therefore, a primary goal in conserving the unknown (species and their distribution) is finding biodiversity surrogates. This study uses remote sensing techniques and animal distribution in Spain to propose a new surrogate - habitat heterogeneity diversity (HHD). HHD was defined using measures of NDVI (Normalized difference vegetation index) and maximum dispersion approach to identify areas that spam habitat heterogeneity among sites. The efficacy of HHD in selecting sites to represent species was compared to the biotic surrogate rarity-weighted richness (RWR), a single NDVI measure, and a null solution. This study also investigated the spatial patterns of RWR and whether the methodology used to estimate HHD influences its efficiency as a surrogate. RWR patterns generally show high values in the north. While the correlations among RWR values were generally moderate, HHD successfully represented species compared to NDVI and null solutions and, in some cases, RWR. HHD is a robust alternative for complementarity-based solutions for solving problems that require the representation of at least one occurrence per species. Since HHD could be calculated using NDVI variables, the cost of conservation planning could be reduced since remote sensing variables are widely available and accessible most of the time. When validated, HHD could be incorporated into spatial conservation prioritization plans alongside other abiotic-based solutions at the same scale that conservation is practiced.