Tree species range shifts at a continental scale: new predictive insights from a process‐based model

Abstract

Summary 1.Climate change has already caused distribution shifts in many species, and climate predictions strongly suggest that these will accelerate in the future. Obtaining reliable predictions of species range shifts under climate change is thus currently one of the most crucial challenges for both ecologists and stakeholders. 2. Here we simulate the distributions of 16 North American tree species at a continental scale for the 21st century according to two IPCC storylines, using a process-based species distribution model that for the first time allows identification of the possible causes of distribution change. 3. Our projections show local extinctions in the south of species ranges (21% of the present distribution, on average), and colonizations of new habitats in the north, though these are limited by dispersal ability for most species. Areas undergoing local extinctions are slightly larger under climate scenario A2 (+3.2 ° C, +22% on average) than B2 (+1.0 ° C, +19% on average). This small difference is caused by nonlinear responses of processes (leaves and flowers phenological processes in particular) to temperature. We also show that local extinction may proceed at a slower rate than forecasted so far. 4. Although predicted distribution shifts are very species-specific, we show that the loss of habitats southward will be mostly due to increased drought mortality and decreased reproductive success, while northward colonizations will be primarily promoted by increased probability of fruit ripening and flower frost survival. 5. Synthesis . Our results show that different species will not face the same risks due to climate change, because their responses to climate differ as well as their dispersal rate. Focusing on processes, our study therefore tempers the alarming conclusions of widely used niche-based models about biodiversity loss, mainly because our predictions take into account the local adaptation and trait plasticity to climate of the species.

From past to future: impact of climate change on range shifts and genetic diversity patterns of circumboreal plants

“…8°latitude to the north in Eurasia and North America. This is in accord with work on Arctic plants predicting that at the end of the century loss of geographic range will generally be higher than the range gain (Alsos et al 2012), but does not correspond to the twofold lower values given for Mediterranean-temperate tree species (Temunovic et al 2013) and temperate tree species under different emission scenarios (Morin and Viner et Chuine 2008). In our different climatic scenarios, the (highly isolated) Central European populations of the three circumboreal plants we studied will become critically endangered or even extinct in the future.…”

The altitude-for-latitude disparity in the range retractions of woody species

“…Consequently, the observed upward elevational shifts of species should translate into latitudinal shifts of tens to hundreds of kilometres based on this altitude-for-latitude model. This expectation is further supported by analyses of common garden experiments (Box 1) [32][33][34][35][36], species-specific process and niche-based models [37][38][39], and the responses of species to past climatic changes [40,41].…”

“…Consequently, rapid lowland range retractions might be imminent, with large-scale dieback poised to occur on a sub-continental scale in some species, as recent reports from North America demonstrate [5,7,30,37,46,47,55,72]. Such impacts will result in significant changes to plant community composition and associated biodiversity, ecosystem function and carbon dynamics.…”

Temperature Sensitivity of Canopy Photosynthesis Phenology in Northern Ecosystems

“…It is well known that species differ in their climatic determinants of phenology. Models also predict that because of this, species will respond in different ways to future climate change (Morin et al 2008). The changes in vegetation or biomes under climate change or land use change will further modify ecosystem carbon cycle in response to temperature change.…”