Paying colonization credit with forest management could accelerate the range shift of temperate trees under climate change

Abstract

The northward migration of several tree species ranges is likely to lag behind climate change due to slow demography, competitive interactions, and dispersal limitations. These will result in a colonization credit, where suitable climate envelopes are left unoccupied, and extinction debt, where tree stands persist at unsuitable climatic locations. While the underlying mechanisms explaining the delayed range shift of forest trees have been investigated, few studies have focused on how management could overcome this lag. Here we extend a forest community state model derived from the metapopulation theory and validated with over 40,000 forest inventory plots, to formulate how forest management can accelerate the response of the boreal-temperate ecotone under warming temperature. We first complete the model equations to represent how four types of forest management may affect the transitions between four forest states: Boreal, Temperate, Mixed and Regeneration. We then simulated the potential of forest management to reduce colonization credit and extinction debt using two complementary approaches to measure the resilience and range shift of the boreal-temperate ecotone in response to warming temperature. Our simulations reveal that paying the colonization credit by planting temperate trees in a stand in Regeneration or Boreal state are likely to i) reduce the return time to equilibrium, ii) increase forest resilience, and iii) move the ecotone towards colder temperatures. Surprisingly, harvesting boreal trees in stands in Boreal or Mixed state were not effective to reduce extinction debt and provide colonization opportunities for temperate trees. Our results suggest that forest management related to planting actions could help the boreal-temperate ecotone keep pace with climate change. Future experiments are required to test these theoretical expectations and make operational recommendations.