The publication, Proceedings of the Royal Society: B shows that species like Woodland Caribou are not expected to do well in a “greener” world.
Globally, climate change and habitat alteration are increasing primary productivity--an increase in vegetation in this context-- in a process that is often termed “global greening.” While these changes may benefit some species, they can harm others. Researchers from across western Canada, led by a team from the Alberta Biodiversity Monitoring Institute’s Caribou Monitoring Unit, studied links between habitat alteration (e.g. forest harvesting), primary productivity, moose, wolves, and caribou across the Canadian boreal forest. While other studies have looked at subsets of these factors, this one is unique in its attempt to tackle them together. The result is a study that considered multiple levels of the food web, from plants to herbivores to carnivores, across 600,000 km 2 of British Columbia, Alberta, Saskatchewan, and the Northwest Territories.
Of all the relationships the researchers tested between factors, the most supported findings were:
● habitat alteration such as forestry leads to higher primary productivity (that is, more shrubby vegetation);
● increased vegetation increases moose densities because their preferred food is more available;
● increased moose density supports a greater density of predators such as wolves in the area; and
● more wolves leads to declining caribou populations
Caribou are adapted to a (historically) nutrient-poor boreal environment, with a correspondingly low rate of reproduction and population growth that can’t be easily exceeded even when food is abundant.
Meanwhile, moose have a much higher reproductive potential that’s unleashed when conditions allow, which in turn means more food for wolves. For caribou, greening is a double whammy: it replaces their preferred lichen-rich habitats with more productive shrub and grass-based ones—which is bad for caribou in its own right—and it ultimately leads to predation on their populations.
Ecosystems are complex, and significant changes in some of their components usually come with consequences elsewhere—caribou now find themselves at the confluence of several such consequences. The more we learn, the more it seems that ultimate solutions to the decline of Woodland Caribou will need to be centered on habitat protection and restoration, with a view to how global phenomena such as climate change will alter basic ecological processes and relationships
Rob Serrouya, Director, Caribou Monitoring Unit
Open-access paper: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2811
More detailed overview of the paper’s methods and findings: