Principal Investigator:
Ronald
Amundson
Professor
Division of Ecosystem Sciences
151 Hilgard Hall
University of California, Berkeley CA 94720
Duration of Project: 2 years
Stallard (1998) focused international attention on the potential importance of the erosive removal of soil C from landscapes, yet there have been no examinations of this process in undisturbed uplands. Because of the large areas of dynamic and actively eroding uplands in California, this process may be a significant (but ignored) means by which C is being sequestered in the state. Therefore, our proposal directly addresses the first goal of the Kearny 2001-2006 mission, "Understand the mechanisms and processes governing the storage and flow of carbon in soils that support California's diverse ecosystems".
Here we build on a decade of intensive geomorphological research on rates of soil production and transport in central California watersheds in order to address soil C cycling.. We propose to combine intensive soil sampling and analyses, and geomorphic modeling, to reconstruct how the landscape-scale distribution of SOC storage develops over time. We hypothesize that large (relative to biologically cycled C) amounts of soil C are eroded from sloping areas and that this C is temporarily stored locally in nearby depositionalsites, leading to positive net ecosystem productivity for the watershed over geological timescales.
At two 0 order watersheds with contrasting geology, we will (1) excavate up
to 80 soil pits in differing erosional/depositional area, (2) determine soil
bulk density and C and N, (3) develop detailed topographic maps of the watersheds
to quantify the relationship between hillslope form and the processes transporting
soil C, and (4) model the rates of soil C erosion/deposition in the watersheds.
The results from the 0 order watersheds will be scaled to higher order watersheds
in order to quantify the potential significance of erosional soil C fluxes over
larger areas.
Our proposed research will directly inform the on-going debate over the nature
of the "missing carbon sink" by improving our understanding of how
C moves through upland landscapes. If our hypothesis is correct, this will signal
the need for including topography-driven soil movement in regional/global C
flux models, and will require further field investigations (into broader ranges
of climate and geology) into the fate of eroded soil C as it is transported
to depositional basins or marine/lacustrine environments.