jabbrv-ltwa-all.ldf jabbrv-ltwa-en.ldf Herbivory is one of the main biotic processes modulating plant diversity and productivity. In tropical forests, insects may remove up to 30% of total leaf biomass, but the effects on vegetation structure/productivity and biodiversity are poorly understood. Insect herbivory might promote or suppress plant growth, first reducing the photosynthetic area but also providing a rather direct path from nutrients in leaves to the plant-available soil pool. In this study, we used a trait-based Dynamic Global Vegetation Model (LPJ-GUESS-NTD), parameterized with unique field data from a tropical mountain forest gradient in southern Ecuador, to analyze how observed leaf-trait dependent insect herbivory influences the functional diversity and productivity of vegetation. According to the model, insect herbivory decreases net primary production by 6% and vegetation carbon storage by 26%. Herbivory also causes a vegetation community trait shift related to the leaf and wood economic spectrum, since with it specific leaf area (SLA) is reduced by 34% and wood specific gravity (WSG) increases by 10% respectively. This herbivory-induced change implies a shift towards a vegetation community with more conservative growth strategies, with negative effects on litter quality and nutrient availability. Accordingly, and in contrast to our expectations, herbivory reduces nutrient availability in the model. Finally, the inclusion of herbivory re-enforces gradients in nutrient availability and increases the community trait dissimilarity across altitudes (beta diversity). Our results suggest that insect herbivory has profound negative impacts on vegetation productivity and biomass in our study area, partly driven through feedbacks between soil processes and changes in plant traits. Furthermore, insect herbivory might be an important factor in shaping vegetation functional diversity.

A document by Mateus Dantas de Paula. Click on the document to view its contents.

Understanding the processes that shape forest functioning, structure and diversity remains challenging, although an increasing amount of data documents forest systems across scales. Forest models have a long history in assimilating various data and ecological knowledge and can simulate forest dynamics over spatio-temporal scales unreachable by most empirical investigations. Here we describe the trajectories of development different forest modelling communities have followed to demonstrate the leverage that computer models offer for advancing the understanding of forest ecosystems. Using three widely applied but contrasting forest modelling approaches - species distribution models, individual-based models and dynamic global vegetation models - as examples, we show how scientific and technical advances have led models beyond their initial objectives and limitations. We provide an overview of recent model applications on current important ecological topics and pinpoint ten key questions that could, and should, be tackled with forest models in the next decade. This shows that forest models, due to their long history of assimilating empirical knowledge, their iterative and continuous development, and their complementarity, represent an invaluable toolkit to address a wide range of theoretical and applied ecological questions, hence fostering a deeper understanding of forest dynamics, particularly in the context of global change.