Boreal forests will be more severely affected by projected anthropogenic climate forcing than mixedwood and northern hardwood forests in eastern Canada

Abstract

Increased anthropogenic climate forcing is projected to have tremendous impacts on global forest ecosystems, with northern biomes being more at risk. ObjectivesTo model the impacts of harvest and increased anthropogenic climate forcing on eastern Canada's forest landscapes and to assess the strong spatial heterogeneity in the severity, the nature and direction of the impacts expected within northern forest regions. MethodsWe used LANDIS-II to project species-specific aboveground biomass (AGB) between 2020 and 2150 under three climate (baseline, RCP 4.5 and RCP 8.5) and two harvest (baseline harvest, no harvest) scenarios within four forest regions (boreal west, boreal east, mixedwood and northern hardwood). ResultsClimate change impacts within the boreal forest regions would mainly result from increases in wildfires activity which will strongly alter total AGB. In the mixedwood and northern hardwood, changes will be less important and will result from climate-induced growth constraints that will alter species composition towards more thermophilous species. Climate-induced impacts were much more important and swifter under RCP 8.5 after 2080 suggesting that eastern Canada's forests might cross important tipping points under strong anthropogenic climate forcing.

Multi‐model projections of tree species performance in Quebec, Canada under future climate change

“…This decline is consistent with studies that show recent trends in forest productivity losses and composition changes, notably at the temperate-boreal ecotone in North America (Brice et al, 2019; Fisichelli et al, 2014; Girardin et al, 2016; Reich et al, 2015;Taylor et al, 2017). It is important to mention, however, that inertia of forest ecosystems(Stralberg et al, 2020,) as modelled in, for example, forest landscape models(Boulanger & Pascual Puigdevall, 2021) could be responsible for the 'stable state' observed within their respective projections. Although productivity and growth are sensitive to yearly variations in climate conditions(Bridge, 2004),F I G U R E 4 Continuedforest composition changes, as projected by, for example, LANDIS-II and Quebec LD, are strongly contingent on processes that cumulate and interact mostly in the long term (e.g.…”

“…We decided not to simulate harvest as not all processed-based models were able to simulate harvest. We suspect, as found by several authors (Boulanger & Pascual Puigdevall, 2021;Bouchard et al, 2019), that harvest could increase or accelerate the decline of late successional species in boreal regions (especially black spruce and balsam fir), and favour pioneer species (trembling aspen). We also presume that harvest will accelerate the migration of thermophilous species into Boreal and Mixedwood forest regions.…”

“…Small windthrows are the main natural disturbances in the Northern Hardwoods forest region (Frelich & Lorimer, 1991;Nolet et al, 2012). Harvest takes place in all the four regions, with cutblock size and proportion of biomass harvested increasing with latitude (Boulanger & Pascual Puigdevall, 2021).…”

“…Five replicates of each climate scenario were run. Although 17 species were included and allowed to interact in LANDIS-II simulations (see Boulanger & Pascual Puigdevall, 2021), we only retrieved aboveground biomass for the six species considered in this study.For the sake of the multi-model assessment, species performance in LANDIS-II was defined by comparing simulated species-specific aboveground biomass under a given climate scenario compared with those obtained under the reference scenario (historical climate) at time = t. See detailed model utilization inBoulanger, Taylor, et al (2017),Boulanger et al (2019), andPascual Puigdevall (2021).2.3.7 | LPJ-LMfire (aboveground biomass)LPJ-LMfire is a dynamic global vegetation model which includes updates of both LPJ and the SPread and InTensity of FIRE (SPITFIRE)…”

Effects of global change on animal biodiversity in boreal forest landscape: an assemblage dissimilarity analysis

“…This increase in temperature could lead to the northward migration of thermophilous hardwood tree species to the detriment of boreal conifers, particularly mid-to-late-successional species (Duveneck et al, 2014; Boulanger et al, 2017; Boulanger and Puigdevall, 2021). Moreover, climate change is expected to directly influence wildfire activity (Boulanger and Puigdevall, 2021), which would favour pioneer and fire-adapted boreal tree species (Boulanger et al, 2017). Significant changes in species composition are expected within the transition zone between boreal and temperate biomes, where several tree species are currently reaching their thermal limits (Brice et al, 2020; Boulanger and Puigdevall, 2021).…”