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

Dennis L Murray,Michael J L Peers,Daniel H Thornton,Rob S A Pickles,Yasmine N Majchrzak,Jeffrey R Row,Morgan Wehtje,Catarina Ferreira,Ben Bond-Lamberty

doi:10.1371/journal.pone.0176706

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.

Highlights

Mounting evidence supports widespread concern that the earth’s biomes are facing rapid and increasingly profound stress associated with climate change [1]
A robust understanding of climate change responses is especially crucial for species that either occupy restricted environmental niche space, or else are found in marginal or rapidly-changing environments, as these groups can be among those most severely impacted by climate change [9]
As with the reported changes corresponding to species distribution, gains in climate suitability within the boreal forest mainly reflect improved climate niche suitability at the northern limits (Figure B in S1 File)

Summary

Introduction

Mounting evidence supports widespread concern that the earth’s biomes are facing rapid and increasingly profound stress associated with climate change [1]. Global trends attributable to climate change include pole-ward (or elevational) range shifts, phenological advances in growth or reproduction, and changes in abundance and community structure [2,3,4]. Most recently, these trends appear to be accelerating across a range of taxa and systems [5,6], leaving little doubt that the present course of environmental change will dramatically alter the structure and function of all ecosystems on earth. Broad-scale and multispecies analyses are necessary to better reveal the likely breadth and extent of climate-driven processes occurring through space and time

Methods

Results

Conclusion