Unlocking the Power of Many – Why Inter-Catchment Comparisons Can Advance Our Understanding of Forest Hydrological Resilience to Climate Warming

English Abstract:

A predictive understanding of forest hydrological resilience in the face of climate change is important because substantial changes to historical water yields place communities that depend of forest water supplies at risk. Hydrological resilience is the ability of a forested catchment to absorb change and maintain or quickly regain hydrological function. Capitalizing on investments into catchment monitoring from provincial/state and federal governments over the past 50+ years, we use novel techniques to explore the hydrological resilience of water yields in natural forested landscapes. In a recent study, we used the theoretical framework of the Budyko curve to explore the elasticity of water yields and changes in water yields related to climate warming – high elasticity indicates resilient water yields, and low elasticity indicates non-resilient water yields. In this study, we consider additional metrics of elasticity [e.g., incorporating stationary (natural, oscillating) vs. non-stationary (anthropogenic, trends) signals in water yields and exploring if catchments with more pronounced oscillations (indicating a system regularly exposed to larger amplitude and/or shorter duration cycles) are more or less vulnerable to climate change]. We then explore hydrological mechanisms (changes in the accessibility of water storages for evapotranspiration) and ecological mechanisms (changes in forest compositions, structure and function) that may contribute to forest expressions of elasticity in response to climate warming. We demonstrate the power of using long-term hydrological monitoring catchments across a range of scales – from a single watershed, to the temperate forest biome, to a range of forest biomes across North America – to “unpack” the complexity and help predict the potential hydrological resilience of catchment water yields to climate change.