Unraveling the Importance of Inter- and Intraspecific Competition for the Adaptation of Forests to Climate Change

Abstract

Climate change implies a new and challenging source of uncertainty for forestry and requires adaptation measures. In the context of silviculture two main approaches have recently been discussed: adapting target tree species composition, and adapting stand density. This review shows that creating mixed stands and controlling stand density through thinning are effective adaptation principles, which both may reduce resource competition among trees. Mixed stands composed of species with different functional traits and foraging strategies increase the likelihood of complementary effects because of reduced (intraspecific) competition pressure and/or facilitation effects. Thinning stands leads to lowered interception and increases in throughfall and soil water availability, improving tree recovery and resilience after drought events. For an adequate interpretation of tree growth responses to drought it is important to distinguish between the term sensitivity, which describes the magnitude of the individual’s response to stress, and the term vulnerability, which describes whether or not the actual stress is crucial for both long-term performance and tree or stand survival, respectively.