Principal Investigator:
Susan E. Trumbore
Department of Earth System Science,
University of California
Irvine, CA 92697
Duration of the Project: 2 years
The role of parent material in soil carbon storage and turnover is potentially important but poorly quantified. Based on an existing but underutilized database, and building on previous work on soil C turnover, we propose to determine the separate and combined effects of climate and parent material on soil C storage and turnover in California uplands.
We will use the California Soil-Vegetation Survey in combination with gridded
climate surfaces to statistically quantify in the relationship between soil
carbon and parent material across a matrix of climate and vegetation types.
In the course of this project we will make this unique GIS-compatible soils
database available to the larger scientific community.
Having already quantified carbon stocks and dynamics across a granite parent
material climosequence, we will do the same across a basalt climosequence. We
will link differences in the amount and turnover time of soil C to mineralogy
by measuring radiocarbon in soil organic matter fractions consisting of one
or a few mineral components in A and B horizons of one soil. We will determine
the turnover times of more rapidly cycling C based on two complementary approaches:
a) Measuring the increase of radiocarbon (14C) in the past 30 years in paired
archived and modern soils (e.g. Trumbore et al. 1996) and b) Comparing the 14C
released by microbial decomposition during incubations with the 14C of different
density fractions. The final product will be an estimate of the capacity of
soils in the Sierra Nevada and Cascade regions to store or release C under future
scenarios of change in climate or vegetation productivity.