Modeling intrinsic potential for beaver (Castor canadensis) habitat to inform restoration and climate change adaptation

Abstract

Through their dam-building activities and subsequent water storage, beaver have the potential to restore riparian ecosystems and offset some of the predicted effects of climate change by modulating streamflow. Thus, it is not surprising that reintroducing beaver to watersheds from which they have been extirpated is an often-used restoration and climate-adaptation strategy. Identifying sites for reintroduction, however, requires detailed information about habitat factors—information that is not often available at broad spatial scales. Here we explore the potential for beaver relocation throughout the Snohomish River Basin in Washington, USA with a model that identifies some of the basic building blocks of beaver habitat suitability and does so by relying solely on remotely sensed data. More specifically, we developed a generalized intrinsic potential model that draws on remotely sensed measures of stream gradient, stream width, and valley width to identify where beaver could become established if suitable vegetation were to be present. Thus, the model serves as a preliminary screening tool that can be applied over relatively large extents. We applied the model to 5,019 stream km and assessed the ability of the model to correctly predict beaver habitat by surveying for beavers in 352 stream reaches. To further assess the potential for relocation, we assessed land ownership, use, and land cover in the landscape surrounding stream reaches with varying levels of intrinsic potential. Model results showed that 33% of streams had moderate or high intrinsic potential for beaver habitat. We found that no site that was classified as having low intrinsic potential had any sign of beavers and that beaver were absent from nearly three quarters of potentially suitable sites, indicating that there are factors preventing the local population from occupying these areas. Of the riparian areas around streams with high intrinsic potential for beaver, 38% are on public lands and 17% are on large tracts of privately-owned timber land. Thus, although there are a large number of areas that could be suitable for relocation and restoration using beavers, current land use patterns may substantially limit feasibility in these areas.

Mapping the status of the North American beaver invasion in the Tierra del Fuego archipelago

“…In the Northern Hemisphere, it was also noted that the habitat requirements largely determined the distribution and abundance of this species [37], where beavers were associated with forests and some open ecosystems [38]. These findings agree with studies that suggest that beaver habitat use is determined by more than just trees or water [37,39,40]. In the archipelago, although the NPP result was linear (more beaver dams in more productive ecosystems), beaver dams were also found in ecosystems with very low productivity (300 gC m 2 yr -1 ).…”

Beaver dam capacity of Canada’s boreal plain in response to environmental change

“…In particular, hummocky parts of the boreal landscape tend to have a disjointed drainage pattern and high density of open water bodies 55 . Beaver also readily inhabit ponds 20 and groundwater seeps 56 which are abundant in the boreal plain. Dams built in these environments are critical locations in boreal plains watersheds for surface water storage 39 , and they are also likely important places of groundwater recharge 10 .…”

“…Thus there is potential for impoundment of large volumes of water in beaver ponds with considerable impact to the park’s streamflow regime. Beaver-mediated enhanced water storage in the boreal plain is likely to become increasingly important with climate change as shallow ponds dry out 20 , 47 .…”

“…Environmental changes resulting from the cumulative impacts of disturbance-recovery dynamics and climate change 17 are expected to considerably alter the ecological and hydrological character of the boreal forest over time 18 . Beaver are likely an important part of enhancing the resiliency of the boreal forest to environmental change 19,20 . Yet, recent and continued environmental changes will also impact the beaver population.…”

Modelling Eurasian beaver foraging habitat and dam suitability, for predicting the location and number of dams throughout catchments in Great Britain

“…(i) A recent and novel approach for identifying areas in a catchment that can support beavers was developed by Dittbrenner et al (2018) who created a Beaver Intrinsic Potential model based on topographic parameters and discounting contemporary land use cover.…”