COS 179-6 - The impact of climate change on European forests productivity is strongly related to changes in tree biodiversity

Friday, August 11, 2017: 9:50 AM
E143-144, Oregon Convention Center
Xavier Morin, Cefe, CNRS, Montpellier, France and Raul Garcia-Valdes, CREAF, Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
Background/Question/Methods

Climate change directly affects forest functioning processes such as productivity. But it also alters forest biodiversity through changes in community composition, which in turn modifies forest productivity. Understanding the interplay between climate change, biodiversity and productivity is thus a decisive task for forest ecologists, but the relative importance of these direct and indirect effects has not been evaluated within a unifying framework yet.

Building on a novel approach using forest succession models to explore diversity-productivity relationships, we explored how climate change may affect these relationships, employing the model ForClim. We quantified how climate change affects the relationship between diversity and productivity along an environmental gradient of 11 sites in Central Europe, by comparing simulations run under “current conditions” and simulation under 2090-2100 conditions according to scenarios from three Regional Climate Models.

We also carried-out another type of simulations to complement our results, through a cross-scaling approach linking species distribution models with a forest succession model. In this design, we first assessed changes in species probability of occurrence, under both current and future climate conditions, to forecast potential species pools along central European forests. Then we simulated community dynamics and forest functioning given the predicted species pools and climate scenarios.

Results/Conclusions

The effect of climate change greatly varied across sites. We found that climate change mostly affects DPRs through the recruitment of new species, which ultimately results in enhanced complementarity, which thus highlights the importance of changes induced by indirect effects on species richness. Furthermore, a loss in tree diversity had a stronger effect on forest productivity in sites experiencing harsher conditions (especially drier) in the 2090-2100 period. The cross-scaling approach showed that climate change may promote forests with less stable productivity over time and with less biomass than under current conditions.

By disentangling direct and indirect effects of climate change on ecosystem functioning, these findings explain why high-diversity forests are expected to be more resilient to climate change.