Standing dead trees as indicators of vertebrate diversity: Bringing continuity to the ecological role of senescent trees in austral temperate forests

Abstract

Standing dead trees are known to house diverse assemblages of vertebrates in temperate forests worldwide. In temperate austral forests of South America, however, the functional role of dead trees has been mostly focused on cavity provision, but other functions remain poorly understood. Thus, we conducted a preliminary study examining the effect of dead trees on the taxonomic diversity of vertebrates in South American temperate forests. Diversity metrics estimated from rarefaction curves and community data augmentation showed that taxonomic diversity of vertebrate species was equal between dead and living trees. Habitat variables equally affected species diversity of vertebrates in dead and living trees. Tree height and elevation had a positive effect while forest cover negatively affected species diversity. The similar diversity and composition of vertebrates found in living and dead trees suggests dead trees are equally valuable for conservation. In austral forests dominated by long-living tree species, the death of a tree is a long process involving the retention of several microhabitats once the tree dies and the enrichment of deadwood structures attracting saproxylic organisms. These findings highlight the need of establishing minimum stocks of dying and senescent trees for achieving ecosystem integrity.