How Does Vegetation Impact Hillslope Response to Changing Channel Incision? Insights into Eco-geomorphological Coupling in the Californian Sierra Nevada and Numerical Landscapes

Abstract:

Vegetation is an active agent in the production and transport of mobile regolith and plays an important role in modulating how hillslopes respond to changes in climate and tectonics. However, the role of vegetation remains a poorly constrained component of existing landscape evolution models. We investigate the role of vegetation in soil production, and how it impacts the hillslope response to changes in channel incision rates using a combination of: (i) empirical observations of coupled ecological and geomorphological changes across topographic knickzones in the Californian Sierra Nevada, obtained from airborne LiDAR data, and (ii) numerical experiments that explicitly incorporate tree throw as a soil production mechanism. The results suggest that the ecological response to changing erosion rates may play a significant role in modulating the evolution of hillslopes adjusting to more rapid rates of fluvial incision, impacting on the nature of the soil-bedrock transition.