Continental divide: Predicting climate-mediated fragmentation and biodiversity loss in the boreal forest

Abstract

Climate change threatens natural landscapes through shifting distribution and abundance of species and attendant change in the structure and function of ecosystems. However, it remains unclear how climate-mediated variation in species’ environmental niche space may lead to large-scale fragmentation of species distributions, altered meta-population dynamics and gene flow, and disrupted ecosystem integrity. Such change may be especially relevant when species distributions are restricted either spatially or to a narrow environmental niche, or when environments are rapidly changing. Here, we use range-wide environmental niche models to posit that climate-mediated range fragmentation aggravates the direct effects of climate change on species in the boreal forest of North America. We show that climate change will directly alter environmental niche suitability for boreal-obligate species of trees, birds and mammals (n = 12), with most species ranges becoming smaller and shifting northward through time. Importantly, species distributions will become increasingly fragmented, as characterized by smaller mean size and greater isolation of environmentally-suitable landscape patches. This loss is especially pronounced along the Ontario-Québec border, where the boreal forest is narrowest and roughly 78% of suitable niche space could disappear by 2080. Despite the diversity of taxa surveyed, patterns of range fragmentation are remarkably consistent, with our models predicting that spruce grouse (Dendragapus canadensis), boreal chickadee (Poecile hudsonicus), moose (Alces americanus) and caribou (Rangifer tarandus) could have entirely disjunct east-west population segments in North America. These findings reveal potentially dire consequences of climate change on population continuity and species diversity in the boreal forest, highlighting the need to better understand: 1) extent and primary drivers of anticipated climate-mediated range loss and fragmentation; 2) diversity of species to be affected by such change; 3) potential for rapid adaptation in the most strongly-affected areas; and 4) potential for invasion by replacement species.

Impact of climate change on the small mammal community of the Yukon boreal forest

“…There is no commercial forestry but some firewood gathering, no agriculture industry, no domestic cattle, and a small mining footprint. The analysis by Murray et al (2017) suggests that for the next 100 years the Kluane ecosystem portion of the boreal forest will be the least affected by climate-induced forest fragmentation and loss. As such, our study could be a boreal forest control in which the climate drivers and the human drivers are not confounded.…”

Impact of rewilding, species introductions and climate change on the structure and function of the Yukon boreal forest ecosystem

“…The advantages we see in trying to judge what will happen to this forest system during the next 50-100 years are that it is a relatively undisturbed ecosystem in the boreal forest biome that stretches from Alaska to Newfoundland and that perhaps it is a test case of what we know and do not know about ecosystem changes. Our analysis, along with that of Murray et al (2017), shows clearly that even though it is often thought of as pristine, changes are occurring associated with climate change and direct human actions.…”

A quantitative analysis on the effects of critical factors limiting the effectiveness of species conservation in future time

“…Although more recent climate projections exist after IPCC AR5, we opted to use the AR4 as it links with the most resolute land‐use projections for Europe (see spatial conflicts with socioeconomic activities). Moreover, there exists considerable analytical evidence that there are no major distinctions in making species distribution modeling from both sources (Murray et al., ; Ring et al., online first; Wright, Schwartz, Hijmans, & Shaffer, ). Each mapped grid cell, i (henceforth, cell), records the local climatic suitability for each species, s , which ranges from zero‐to‐one, for each time‐period, t ().…”