Hillslope Hydrology Influences the Spatial and Temporal Patterns of Remotely Sensed Ecosystem Productivity

Prediction of ecosystem responses to a changing climate is challenging at the landscape to regional scale, in part because topography creates various habitats and influences ecosystem productivity in complex ways. However, the effects of topography on ecosystem function remain poorly characterized and quantified. To address this knowledge gap, we developed a framework to systematically quantify and evaluate the effects of topographic convergence, elevation, aspect, and forest type on the long-term (1986-2011) average and interannual variability of remotely sensed ecosystem productivity. In a forested watershed in the Rocky Mountains, spanning elevations from 1,800 to 4,000 m, we found a prevalent and positive influence of topographic convergence on long-term productivity. Interannual growing season productivity was positively related to precipitation, with higher sensitivity in low elevation and highly productive areas and lower sensitivity in convergent areas. Our findings highlight the influence of topographic complexity on both long-term and interannual variations of ecosystem productivity and have implications for understanding and prediction of ecosystem dynamics at hillslope to regional scales.