The Weakest Link : Assessing Vulnerabilities, Risks, And Tree Adaptive Capacity Of Temperate Forests To Global Changes

Forests are shaped by disturbances u2013 for better or worse. Disturbances can be analyzed individually, but it is their interactions that are likely to lead to megadisturbances regimes u2013 such as hotter droughts and more extensive and severe wildfires u2013 challenging the main objectives of forest management, which are to provide ecosystem services sustainably to society and to restore or maintain its resilience. Applying resilience concepts in forest management is especially relevant in the context of climate variability because the stochastic nature of disturbances often makes them difficult to predict.The resistance of a forest to disturbance depends largely on the species composition of the canopy trees that currently dominate the forest; yet its adaptive capacity may reside primarily in future canopy replacement by trees of the same or other species. Therefore, we focused on (i) the effect of disturbances on a subset of biological characteristics (e.g., dispersal, shade tolerance) of 30 tree species of temperate forests; and (ii) their tolerance to a wide range of disturbances (e.g., drought, insects) for both the overstory and regeneration strata. While recognizing that ecosystem collapse will likely manifest itself differently depending on landscape context, we provide a systematic approach that can be applied to any forest to evaluate the risk of collapsing, as a result of the loss of ecosystem resistance and resilience. We argue that, given the complexities and uncertainties related to increasingly frequent and severe disturbances, management should aim at increasing diversity thus keeping more options open for the future if conditions or responses change.