Hydro-ecological consequences of beaver reintroduction

The Eurasian Beaver (Castor fiber), was hunted to near extinction in Europe and complete extinction in Great Britain (GB) ca. 400 years ago. Beavers were a common and widespread feature of the riparian landscape, arguably exerting the single biggest zoomorphic influence on rivers during the Anthropocene and for millennia before14. Beavers represent the very epitome of a keystone species, engineering ecosystems to suit their needs and supporting a wide variety of wildlife via the creation and maintenance of wetland habitats. Removal of the beaver from aquatic ecosystems is hypothesised to have caused the collapse of food and animal webs supported by beaver engineered dams, canals and lodges9,23,30. Furthermore, we argue profound alteration to ecohydrological structure and function of the fluvial and riparian landscape occurred due to extirpation of beavers, accelerating through the Anthropocene with intensification of landuse14. Now beaver populations are expanding rapidly in GB, we are at a critical time to understand the ecohydrological impacts beaver reintroduction might deliver, in the densely populated, intensively managed landscapes that beavers will colonise. Whilst a growing body of evidence exists to understand the impacts of beaver reintroduction in terms of biodiversity, a scientifically rigorous integrated evaluation of impacts upon ecohydrology (i.e. water resources and aquatic ecology) is lacking and called for by project partners (PPs) to create new knowledge and thus inform national policy and future management of beaver populations. Research is needed to: (1) Quantify how beaver distribution and activity vary geographically across GB (2) Quantify impact of beaver activity, particularly beaver damming, on ecohydrology across scales and land-uses, (3) Develop nationally-available datasets to map habitat suitability and create ecohydro-topographic products in support of; (4) Spatially-explicit models of beaver-impacted ecohydrology, to aid decision-making and local management as a template for wider use.