HR: 1330h
AN: B32B-0388    [PDF]
TI: Controls on Gross Process Rates in Terrestrial Ecosystems: A Literature Synthesis
AU: * Booth, M S
EM: mbooth@iri.columbia.edu
AF: The Earth Institute, Lamont Doherty Earth Observatory, Columbia University, Nyack, NY 10964 United States
AU: Stark, J M
EM: jstark@biology.usu.edu
AF: Department of Biology and the Ecology Center, Utah State University, Logan, UT 84322 United States
AU: Rastetter, E
EM: erastett@mbl.edu
AF: The Ecosystems Center, Woods Hole Marine Biological Laboratory, Woods Hole, MA 02543 United States
AB: Isotope pool dilution studies are increasingly reported in the soils and ecology literature as a means of measuring the gross rates of mineralization, nitrification, and inorganic N assimilation in soils. We assembled data on soils factors and gross rates from forest, grassland, and agricultural systems to attempt to answer three general questions, using regression and other analytical approaches. First, what factors appear to be the major drivers for production and consumption of inorganic N as measured by isotope dilution studies? Second, do rates, and the relationships between drivers and rates, differ among ecosystems? Finally, do methodological issues inherent to the isotope dilution technique affect results? Our review of the literature indicates the importance of soil C and N as primary drivers for mineralization. Nitrification rate is primarily driven by ammonium supply, but does not keep pace with mineralization to the same extent as heterotrophic uptake. While substrate supply generally determines gross production rates, differences in organic matter quality between ecosystem types also influences the production and fate of mineralized N. Soil organic matter from grassland sites appears to be inherently more mineralizable than that from wooded sites, while soil organic matter depletion in agricultural systems is an important determinant of gross process rates. The isotope dilution technique is a valid approach that produces results congruent with what we already know about N cycling, while extending and refining our knowledge of actual production rates and fates of mineralized N.
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting