Does Causation Matter? Post-disturbance Response of Incised Montane Meadow Streams to Restoration.

Abstract:

Land use disturbance from grazing, timber harvest, and transportation infrastructure has been implicated in stream incision within groundwater-dependent montane meadow ecosystems, particularly in the Sierra Nevada of California. Restoration approaches, such as the widely-used "Plug-and-Pond" technique, attempt to restore groundwater levels in incised meadows by introducing shallow, meandering channel morphologies that support more frequent overbank flows and prevent meadow dewatering via seepage to stream networks. Systematic field surveys of over ten "Plug-and-Pond" projects built at least eight years ago and distributed across the Sierra Nevada indicate that pre- and post-restoration basin-scale and meadow-scale sediment transport strongly influence restoration outcomes. The scale of anthropogenic disturbance, along with abiotic factors such as climatic gradients and meadow-scale soil characteristics, influence the resilience of restored meadow systems. Based on these observations and analyses, a conceptual model of meadow ecosystem vulnerability to disturbance and potential for restoration prominently features multi-scaled geomorphic feedbacks that incorporate the influence of geology, climate, vegetation, and hydrology.