National-scale mapping of ecosystem services in Canada to support watershed management

Canada's ecosystems provide vital climate and water regulation services, but nationally consistent assessments integrating multiple ecosystem services (ESs) remain limited. Here, we report a national assessment of three key regulating ESs: carbon storage, sediment retention, and nutrient retention. Carbon density is highest in western mountain forests, boreal forests, and peatland-rich regions, whereas agricultural watersheds in the Prairies and southern Canada combine lower carbon storage with high nutrient inputs and export. Sediment retention is strongest where steep, erosion-prone landscapes retain forest cover, particularly in western Canada. Integrating services identifies candidate protection priorities in forested mountain watersheds that jointly support high carbon storage and sediment regulation, as well as candidate restoration priorities in intensively farmed watersheds where high nutrient export and reduced carbon storage coincide. Downstream population exposure refines these priorities toward areas where interventions may provide greater societal benefit. This assessment provides a consistent national baseline for cross-jurisdictional watershed management and environmental planning.