Public LiDAR data are an important tool for the detection of saproxylic insect hotspots in Mediterranean forests and their connectivity

Abstract

Light Detection and Ranging (LiDAR) is a remote sensing technique with multiple uses throughout scientific fields. It can also be used to transfer point data measured in the field to broader spatial scales, which might enable the evaluation of habitats over large areas and define biodiversity hotspots. Our study took place in Cabañeros National Park, which is situated in the Mediterranean, namely, central Spain, and its vegetation is dominated by forest and impenetrable scrubland. LiDAR was used to detect veteran trees as key elements for a highly diverse saproxylic community. The saproxylic beetle community inhabiting tree hollows was studied among different forest types and habitats to determine its preferences. We identified potential hotspots for the saproxylic beetle community of tree hollows both inside and outside of the park, as well as the connectivity of suitable habitat patches. This was based on the species response to the spatial partitioning of the landscape. We found that not all potentially suitable forest types hosted the same saproxylic diversity or similar species compositions. In addition, forest distribution and connectivity inside and outside of the park also varied highly among forest types and habitats, where the most diverse deciduous oak forest was also the least connected together with the riparian forest. The evergreen oak forest could act as a habitat linkage for most of the threatened and less mobile species in the park. However, the low connectivity of the most diverse forest types in the park surroundings can compromise the persistence of saproxylic diversity in the near future. We concluded that LiDAR data were an effective tool for estimating saproxylic beetle diversity distribution over large-scale areas in the context of landscapes with low accessibility. Additionally, this tool allowed us to identify the most threatened forest types and critical patches for connectivity persistence where management practices capable of accelerating tree veteranisation could help to increase adequate forest connectivity in the region.