Soil organic matter dynamics: a cross-ecosystem approach – support for a cross-LTER workshop
LTER Network Office,
Co-Principal Investigator (PI: Kate Lajtha, Oregon State University)
Organized a 2-day meeting in 2010 bring together scientists from several LTER sites interested in comparative SOM analysis. Our goal was to discuss the various tools and techniques that could and should be used in experimental SOM studies as well as to plan additional cross-site comparisons. The goal was to have scientists conducting quite different experiments, such as N fertilization studies, harvest or biodiversity studies, alien plant invasion measurements, or even DIRT studies, but who all wanted to examine soil organic matter as a response variable, could agree on some standard analytical techniques so that data set could be used in synthetic studies. We also wanted a time when the PIs of the different DIRT experiments could meet for a few hours to plan joint publication of existing data as well as to standardize other measurements to allow for future comparative analysis and publication. Thus participants included faculty and students involved in the Harvard Forest chronic N analysis, all the DIRT site lead scientists, an emerging scientist studying shrub invasions in grasslands, and forest clearing experiments.
Vulnerability of soil organic matter to temperature changes: Exploring constraints due to substrate decomposability and microbial community structure.
National Science Foundation, Division of Environmental Biology, Award #0444880
Co-Principal Investigator (PI: Rich Conant, Colorado State University)
Recent research suggests that even modest temperature increases could cause large releases of CO2 from soils. A one-degree temperature increase could prompt soil carbon losses (as CO2) equivalent to five times the annual CO2 release from all fossil fuel burning. However, such forecasts are based on results from short-term studies that implicitly assume all of the carbon in the soil is uniformly temperature-sensitive. The bulk of applicable research suggests that older, more resistant carbon fractions may be less temperature-sensitive than younger, less resistant carbon fractions. This project will evaluate the extent to which the physical, chemical, and biochemical mechanisms that protect soil carbon from decomposition act to reduce the temperature sensitivity of soil carbon. An important corollary is that soil carbon stocks are less vulnerable to changes in temperature than previously supposed. As a part of this project, we will evaluate temperature sensitivities of soil carbon fractions in soils that differ with regard to their relative abundances of labile versus relatively stable carbon. Results from this work will reduce uncertainty about the vulnerability of soil carbon stocks to changes in temperature, thus improving information available to aid decision makers. This research will also advance our understanding of basic ecosystem dynamics, present a number of unique opportunities for undergraduate and graduate training, and build international collaboration.