Long-term land transformation alters potential ecological corridors and increases functional connectivity cost among nature reserves in Guangdong, China

The functional connectivity of nature reserve networks affects species dispersal, conservation effectiveness and even the integrity of local ecosystems. Drastic land transformation might bring about challenges in the formation of nature reserve networks. In this study, we combined land cover data from 1992 to 2020 and terrestrial nature reserves to model potential ecological corridors with the least cost-weighted distance method in Guangdong Province, China. We analyzed the changes in potential ecological corridors and defined the variations in the cumulative cost-weighted distance with long-term land transformation. Inefficient corridors and conservation priorities were also identified. Our results indicate that the number, spatial distribution and patch pairing pattern of potential ecological corridors are affected by the increasing cost-weighted distance. Before 2015, the cost and total length of the potential ecological corridors increased and then decreased until 2020. The variations in potential ecological corridors are induced by the transformation of multiple land covers, with the expansion of croplands and urban areas, and the degradation of shrublands and grasslands. The grids with higher resistance values, namely, urban areas and croplands, in the potential ecological corridors increase, resulting in the increase of the functional connectivity cost. In terms of the composition of potential ecological corridors, compared with urban expansions, the proportion of cropland grids increased slightly but with a larger base and contributed more to the cost increase. Therefore, it is recommended that key ecological corridors and nodes are not to be utilized, which would increase dispersal cost of wild species, and we suggest a more dynamic and integral perspective for effectively managing land resources and designing regional ecological corridors.