Assessing how vegetation controls hillslope soil processes is a challenging problem, as few abiotic landscapes exist as observational controls. Here we identify five avenues to examine how actively eroding hillslope soils and processes would differ without vegetation, and we explore some potential feedbacks that may result in landscape resilience on vegetated hillslopes. The various approaches suggest that a plant-free world would be characterized by largely soil-free hillslopes, that plants may control the maximum thickness of soils on slopes, that vegetated landforms erode at rates about one order of magnitude faster than plant-free outcrops in comparable settings, and that vegetated hillslope soils generally maintain long residence times such that both N and P sufficiency for ecosystems is the norm. We conclude that quantitatively parameterizing biota within process-based hillslope models needs to be a priority in order to project how human activity may further impact the soil mantle.
Bibliographical noteFunding Information:
The authors all acknowledge the support from the NSF ( DEB 0408122 ) and ( EAR 0443016 ) Programs. RA received support from the University of California Agricultural Experiment Station . The manuscript was greatly improved by the critical reviews of S. Follain, C.S. Riebe, J. Mason, and an anonymous reviewer. We thank Associate Editor R.A. Marston for handling the review process and greatly improving the manuscript.