Résumé
1. Over the coming decades, the predicted increase in frequency and
intensity of extreme events such as droughts is likely to have a strong
effect on forest functioning. Recent studies have shown that species
mixing may buffer the temporal variability of productivity. However, most
studies have focused on temporal stability of productivity, while species
mixing may also affect forest resilience to extreme events. Our
understanding of mechanisms underlying species mixing effects on forest
stability and resilience remains limited because we ignore how changes
from intraspecific to interspecific interactions in the neighbourhood of a
given tree might affect its stability and resilience to extreme drought
(i.e. response during and after this drought). This is crucial to better
understand forests’ response to climate change and how diversity may help
maintain forest functioning. 2. Here we analysed how local intra‐ or
interspecific interactions may affect the temporal stability and
resilience to drought of individual trees in French mountain forests,
using basal area increment data over the previous 20 years for Fagus
sylvatica, Abies alba and Quercus pubescens. We analysed the effect of
interspecific competition on (a) the temporal stability and (b) the
resilience to drought (resistance and recovery) of individual tree radial
growth. 3. We found no significant interspecific competition effect on
temporal stability, but species‐specific effects on tree growth resilience
to drought. There was a positive effect of heterospecific proportion on
the drought resilience of Q. pubescens, a negative effect for A. alba and
no effect for F. sylvatica. These differences may be related to
interspecific differences in water use or rooting depth. 4. Synthesis: In
this study, we showed that stand composition influences individual tree
growth resilience to drought, but this effect varied depending on the
species and its physiological responses. Our study also highlighted that a
lack of biodiversity effect on long‐term stability might hide
important effects on short‐term resilience to extreme climatic events.
This may have important implications in the face of climate change.