Rapid 21st century climate change projected to shift composition and growth of Canada’s Acadian Forest Region

Forest ecosystems contain several climate‐sensitive drivers that respond differentially to changes in climate and climate variability. For example, growth and regeneration processes are “stand‐scale” drivers, while natural disturbances operate at “landscape scale”. The relative contributions of these different scale drivers of change in ecosystems create great uncertainty when simulating potential responses of a forest to changes in climate. Here, we assess those contributions, along with harvesting effects, on biomass (both total and of individual species) in the southern boreal forest of Canada under three climate scenarios (RCP 2.6, RCP 4.5 and RCP 8.5). Projections were performed for three future 30‐year time periods, in four study regions located on an east–west transect, using a forest landscape model (LANDIS‐II), parameterized using a forest patch model (PICUS). Projected future impacts were assessed for each driver of change, and found to vary greatly among regions, species, future period and forcing scenarios. Fire, and stand‐scale climate‐induced impacts, had the strongest effects on forest vegetation, as well as on total and species’ biomass under most RCP scenarios, but the largest impacts occurred mostly after 2050, particularly with the RCP 8.5 scenario. The relative importance and trends in species‐specific impacts varied, both spatially and according to the different RCP scenarios. Western regions were generally more sensitive to stand‐scale climate‐induced changes, whereas eastern regions were more sensitive to changes in fire regime. Our study also highlights the importance of considering the prevalence of species‐level functional traits when assessing the sensitivity of forest landscapes to a given driver of change in the context of increasing anthropogenic climate forcing. Synthesis. Increases in fire activity, and direct impacts of climate change on forest growth and regeneration, will be the most important drivers of future changes in southern boreal forest landscapes.

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“…A more complete description of the model, and how it was parameterized and validated, can be found in Taylor et al. () as well as in Appendix .…”

Section: Methodsmentioning

confidence: 99%

“…Interactions among patches are simulated explicitly, including shading effects (captured using a 3D canopy light module) and seed dispersal. A more complete description of the model, and how it was parameterized and validated, can be found in Taylor et al (2017) as well as in Appendix S3.…”

Section: The Picus Forest Gap Modelmentioning

confidence: 99%

Stand‐level drivers most important in determining boreal forest response to climate change

et al. 2017

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“…Ecotones of eastern North America may face exceptionally strong climate forcing in the future (Hayhoe et al, ). This may cause severe consequences for ecosystems because ecotones are expected to be particularly sensitive to climate change as many species are currently at the peripheries of their geographic distributions or environmental tolerance ranges (Taylor et al, ). Moreover, it is likely that climate change impacts will be spatially heterogeneous and nonlinear due to differences in climate, edaphic conditions, and competitive interactions among other factors (Creutzburg et al, ; Frey et al, ).…”

Section: Introductionmentioning

confidence: 99%

The climate sensitivity of carbon, timber, and species richness covaries with forest age in boreal–temperate North America

Thom

Golivets

Edling

et al. 2019

Global Change Biology

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Climate change threatens the provisioning of forest ecosystem services and biodiversity (ESB). The climate sensitivity of ESB may vary with forest development from young to old‐growth conditions as structure and composition shift over time and space. This study addresses knowledge gaps hindering implementation of adaptive forest management strategies to sustain ESB. We focused on a number of ESB indicators to (a) analyze associations among carbon storage, timber growth rate, and species richness along a forest development gradient; (b) test the sensitivity of these associations to climatic changes; and (c) identify hotspots of climate sensitivity across the boreal–temperate forests of eastern North America. From pre‐existing databases and literature, we compiled a unique dataset of 18,507 forest plots. We used a full Bayesian framework to quantify responses of nine ESB indicators. The Bayesian models were used to assess the sensitivity of these indicators and their associations to projected increases in temperature and precipitation. We found the strongest association among the investigated ESB indicators in old forests (>170 years). These forests simultaneously support high levels of carbon storage, timber growth, and species richness. Older forests also exhibit low climate sensitivity of associations among ESB indicators as compared to younger forests. While regions with a currently low combined ESB performance benefitted from climate change, regions with a high ESB performance were particularly vulnerable to climate change. In particular, climate sensitivity was highest east and southeast of the Great Lakes, signaling potential priority areas for adaptive management. Our findings suggest that strategies aimed at enhancing the representation of older forest conditions at landscape scales will help sustain ESB in a changing world.

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“…However, balsam fir is a cold-adapted boreal species that is at high-risk under the predicted future climate conditions, particularly in the Acadian region (Bourque and Hassan 2008;Taylor et al 2017). Hence, future vegetation management and tending treatments (e.g.…”

Section: Management Implicationsmentioning

confidence: 99%

“…Balsam fir is a cold-adapted boreal species that is at high-risk under the predicted future climate conditions, particularly in the Acadian Region of Canada (Bourque and Hassan 2008;Taylor et al 2017). Additionally, there are increasing concerns that the cumulative effects of forest management activities are posing a risk to the sustainability of both Canada's forests and forest industry, especially with the added pressure of climate change (Gauthier et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Legacy effects of precommercial thinning on the natural regeneration of next rotation balsam fir stands in eastern Canada

Canuel¹,

Thiffault²,

Hoepting³

et al. 2019

Silva Fenn.

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The Green River precommercial thinning (PCT) trial was established between 1959â1961 in New Brunswick (Canada) within natural balsam fir ( (L.) Mill.)-dominated stands. Three silviculture scenarios differing only by the increasing nominal spacings of PCT treatments (1.2 m, 1.8 m, 2.4 m) were compared to an unthinned control within randomized replicates that were clearcut harvested in 2008 and treated with herbicide in 2011. During the fourth post-harvest growing season, we assessed regeneration, competing vegetation and coarse woody debris (CWD; differentiated between large woody debris and slash) to assess the legacy effects of PCT on regeneration of next rotation stands. Our results confirmed that silviculture scenarios including PCT significantly increased conifer stocking in treated plots compared to control conditions, but only in the 1.8 m nominal spacing. Considering that treated and untreated stands were fully stocked, we conclude that PCT using the spacing gradient tested has no legacy effect on the regeneration of next rotation natural balsam fir stands. Given the known sensitivity of balsam fir to future climate conditions in this region, we suggest that future treatments should promote tree species diversity to support ecosystem resilience to climate change by favouring more warm-adapted species, such as some hardwoods.Abies balsamea

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Rapid 21st century climate change projected to shift composition and growth of Canada’s Acadian Forest Region

Cited by 81 publications

References 65 publications

Stand‐level drivers most important in determining boreal forest response to climate change

Stand‐level drivers most important in determining boreal forest response to climate change

The climate sensitivity of carbon, timber, and species richness covaries with forest age in boreal–temperate North America

Legacy effects of precommercial thinning on the natural regeneration of next rotation balsam fir stands in eastern Canada

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