Natural woodlands hold more diverse, abundant, and unique biota than novel anthropogenic forests: a multi-group assessment

Abstract

Biodiversity sustained by natural ecosystems, particularly forests, provides ecosystem services essential to human well-being. However, many forests have been severely transformed, notably via monospecific plantations and the spread of invasive species. Given the extension of these novel anthropogenic forests (plantations and invasive copses), it is critical to know how they can support forest biodiversity, particularly in highly humanized biodiversity hotspots as the southwest Mediterranean Europe. Because the effects likely vary across taxonomic groups, such assessments require an integrative multi-group approach. Here, we evaluated the abundance, richness, and composition of shrubs, herbs, macrofungi, ground and flying arthropods, birds, small mammals, carnivores, and bats across the four most common forest types in Central Portugal, namely: natural oak woodlands (dominated by Quercus faginea Lam.) and anthropogenic forests, invasive Acacia dealbata Link copses, Pinus pinaster Aiton plantations (native), and Eucalyptus globulus Labill. plantations (exotic). Oak woodlands sustained higher abundance, diversity, and a unique species composition compared to the other forests, especially those dominated by exotic species. The greatest changes in biodiversity occurred in herbs and birds. Contrary to our expectations, species richness and composition of macrofungi and carnivores in acacia copses were similar to those of oak woodlands, revealing that groups respond differently to forest changes. The large-scale replacement of natural forests by novel anthropogenic forests has significant negative impacts in most, but not all groups, which should be actively considered for integrative conservation strategies.