Résumé
While it is widely acknowledged that forest biodiversity contributes to
climate change mitigation through improved carbon sequestration,
conversely how climate affects tree species diversity - forest
productivity relationships is still poorly understood. We combined the
results of long-term experiments where forest mixtures and corresponding
monocultures were compared on the same site to estimate the yield of
mixed-species stands at a global scale, and its response to climatic
factors. We found positive mixture effects on productivity using a
meta-analysis of 126 cases studies established at 60 sites spread across
five continents. Overall, the productivity of mixed-species forests was
15% greater than the average of their component monocultures, and not
statistically lower than productivity of the best component monoculture.
Productivity gains in mixed-species stands were not affected by tree age
or stand species composition but significantly increased with local
precipitation. The results should guide better use of tree species
combinations in managed forests and suggest that increased drought
severity under climate change might reduce the atmospheric carbon
sequestration capacity of natural forests.