Understanding the impacts of tropical selective logging on ecological mechanisms

Selectively logged tropical forests have been recommended for forest protection and restoration initiatives as these forests maintain a substantial amount of biodiversity and ecosystem functions compared to other tropical land-uses. Most work on selective logging impacts on biodiversity examines species richness, abundance and community composition, yet these metrics can conceal underlying impacts. It is important that we examine the impacts of logging on processes that underpin biodiversity changes, including species’ vital rates (i.e. survival, reproductive success and movement) and community function (i.e. mass-abundance scaling). In Chapter 2, I conducted a literature review to examine the state of our current knowledge on how tropical land-use change impacts species’ vital rates. I found that empirical research on species’ vital rates across taxa and regions were greatly lacking and had considerable variation, with some taxa and land-use biases. In Chapter 3, I focused explicitly on tropical selective logging and investigated its impacts on the mass–abundance scaling of avian communities, an underlying response describing the flow of energy through communities, by conducting a meta-analysis to examine pantropical trends. Only the omnivore guild from mist-netting studies and the frugivore guild from point-count studies had mass-abundance relationships affected by selective logging. I then used field data from a capture-mark-recapture mist-netting study of Bornean understory birds to assess species’ vital rate responses (i.e. local movements and survival) to selective logging at the community- and species-level. In Chapter 4, I developed hierarchical Bayesian models, adapting developments from joint-species modelling, to assess local avian movement and found a higher probability of moving shorter distances (below 200 m) in logged forests and higher movement probability at longer distances (above 200 m) in unlogged forests across 71 species. Finally, in Chapter 5, I developed a multi-species hierarchical Cormack-Jolly-Seber model in a Bayesian framework to determine avian survival rates, revealing similar apparent survival probabilities across 71 species in both unlogged and logged forests. Together, these results suggest limited impacts on avian species and communities. This highlights the potential high ecological value of selectively logged forests, lending further support for the protection of these forests for biodiversity conservation. Integrating post-logging management interventions with various restoration funds, long-term commercial investments, and effective governance will drive transformative change for the long-term environmentally sustainable management of logging concessions.