LTREB: Long-term Detrital Controls on Soil Organic Matter Stabilization

Oregon State University, Corvallis OR

Investigators

Abstract

Soil organic matter (SOM) contains more carbon than plant biomass and the atmosphere combined. Despite its important role in the global life support system, interactions among biological, chemical, and physical processes regulating SOM accumulation, stabilization, and turnover are poorly understood. The DIRT (Detrital Inputs and Removal Treatments) experiment, started at the H.J. Andrews Forest in 1997, is a multi-decade experiment that manipulates plant-litter inputs to large plots in a western coniferous forest. This experiment is designed to address such questions as: what controls the long-term storage of carbon in forest soils? What chemical and physical fractions of SOM are most stable? Can added inputs of detritus increase soil carbon storage, or is maximum storage determined exclusively by climate and soil mineralogy? By following changes in soil carbon in the DIRT plots over the next few decades, we will address these long-term questions directly. The multi-decade, experimental nature of the DIRT experiment is uniquely suited to explore the role of plant detrital quality and quantity in determining SOM accumulation, which is a significant unknown factor in current ecosystem models. In addition, this research focuses on research training of undergraduate Honors students, and this experiment will be incorporated into an Honors Ecology course required of all Honors Environmental Science students at Oregon State University. Both data and soils from this experiment will be made available to researchers across the globe through the Andrews LTER web site. This experiment will be available to researchers, students and climate modelers for decades to come.