Post-logging changes in a neotropical dry forest composition and structure modify the ecosystem functioning

Abstract

Native forests are considered to be the main centers of terrestrial diversity in the world and they provide important ecosystem services for humanity. Unsustainable logging is currently-one of the greatest threats to the biodiversity of these forests. In northwestern Argentina, about 90 % of the piedmont forest in the Southern Yungas has been transformed and the remaining 10% is being intensively logged. The aim of this study was to identify post-logging changes in the structural and compositional attributes affecting the functionality of a dry forest in Argentina. In the control forest, we recorded 1559 individuals from 45 tree species and 22 families, and at post-logging forest, 1376 trees from 47 species and 25 families. Logging affected the forest structure by decreasing timber tree density and basal area. In addition, at the post-logging forest, we observed an increase in the density of non-timber trees and in the horizontal understory cover, which were associated with the normalized difference vegetation index, thus, affecting the forest functioning. The threatened timber species Amburana cearensis and Jacaranda mimosifolia were not recorded in the logged forest. In the control, four timber species had the highest importance value indexes (IVI): Phyllostilon rhamnoides, Anadenanthera colubrina, Calicophylum multiflorum, and Myracrodruon urundeuva. Additionally, in the logged forest there was a change in the species order regarding the IVI, with A. colubrina, P. rhamnoides, Cordia americana, and a non-valuable timber species (Ocotea puberula) being the most important tree species. In order to preserve the economic and ecological value of the piedmont forest, the density of non-timber tree species and the horizontal understory cover must be maintained at values close to the control forest. These guidelines can be implemented by applying low-impact logging techniques.