Migration‐based simulations for Canadian trees show limited tracking of suitable climate under climate change

Abstract

Aim: Species distribution models typically project climatically suitable habitat for trees in eastern North America to shift hundreds of kilometres this century. We simulated potential migration, accounting for various traits that affect species' ability to track climatically suitable habitat.Location: Eastern Canada, covering ~3.7 million km 2 . Methods:We simulated migration-constrained range shifts through 2100 using a hybrid approach combining projections of climatically suitable habitat based on two Representative Concentration Pathways (RCP4.5, RCP8.5) for three time periods and two species distribution modelling approaches with process-based models parameterized using data related to dispersal ability and generation time. We developed a unique "migration kernel" that uses seed dispersal traits and observed migration velocities to obtain kernel shape and dispersal probabilities for each tree species. We then calculated lags between the migration-constrained range limits obtained through simulations and limits of climatically suitable habitat.Results: All species demonstrated northward range shifts at the leading edge of their simulated distribution through 2100, but the magnitude and rate of that shift varied by species and time period. Climatically suitable habitat limits were found to be north of simulated distribution limits across both RCPs, with lags increasing through time.On average, simulated distribution that remained within climatically suitable habitat declined more under RCP8.5 than RCP4.5, with large areas of the rear edge of the simulated distribution becoming partially or completely climatically unsuitable for many species.Main conclusions: Climatically suitable habitat limits projected for 2100 far exceeded migration-constrained range limits for all 10 tree species, particularly for temperate species. This study underlines the limited extent to which tree species will track climate change via natural migration. Integrating observed migration velocities, seed dispersal and generation time with SDM outputs allows for more realistic evaluations | 2331 BOISVERT-MARSH et al.

Climate and dispersal limitation drive tree species range shifts in post-glacial Europe: results from dynamic simulations

“…cold tolerance and high dispersal rates and seed production in Pinus sylvestris) experienced almost no migration lag. The mismatch between the appearance of suitable habitats and range filling has already been observed not only in post-glacial periods (Herzschuh et al, 2016;Talluto et al, 2017;Rumpf et al, 2019) but also in recent decades for a number of species (Lenoir et al, 2020), and especially in northern edge limits and ecotone transitions (Vissault et al, 2020;Boisvert-Marsh et al, 2022). Thus, the inclusion of dispersal limitation and migration constraints in vegetation models would likely improve the prediction of tree range shifts in the future.…”

Unravelling the biogeographic determinants of tree growth sensitivity to freeze and drought in Canada's forests

“…In the boreal forest, individuals of a given tree species usually grow better at warmer temperatures than at colder ones (Way & Oren, 2010). Species distribution models are based on this principle of climatically suitable habitat between rear and leading edges of species distributions: they typically project considerable increases in climatically suitable habitat for tree species at northern leading edges, and declines at rear edges, with warming (Bernal‐Escobar et al., 2022; Boisvert‐Marsh et al., 2022; McKenney et al., 2007). Spatial projections based on static‐tree growth and climate relationships corroborate these predictions, with strong temperature limitation of tree growth in cold and humid regions, and strong precipitation limitation in dry regions (Babst et al., 2019; Charney et al., 2016).…”

“…Greater warming is expected in winter, and in the north, although in the central regions of the continent, summer temperatures may increase as much in the south as in the north (Prairie Climate Centre, 2019; Price et al., 2013). Consequently, a drastic increase in forest mortality and poleward climate niche shifts are expected, raising serious questions about the ability of trees to evolve or acclimate and persist in the face of these rapid changes (Boisvert‐Marsh et al., 2022; Hammond et al., 2022). From past selective climatic pressures, tree species have developed evolutionary patterns to acclimate and adapt to the heterogeneous environments that make up their geographic distributions (Canham et al., 2018; Leites et al., 2019).…”

Competitive interactions under current climate allow temperate tree species to grow and survive in boreal mixedwood forest

“…Caspersen and Saprunoff (2005) demonstrated that inappropriate substrates, more than seed dispersal, limit the abundance of yellow birch and sugar maple at the northern limit of their distribution. In addition, at a broader spatial scale, the demographic characteristics of temperate species, such as late sexual maturity, reproductive strategies with cycles of 3–7 years and their seed dispersal, will constrain their poleward migration even with the projected shift of their potential bioclimatic range with the current rate of climate change (Aitken et al 2008, Hossain et al 2017, Boisvert‐Marsh et al 2022).…”