No abstract

No abstract

This document was prepared as an account of Government-sponsored work and describes a numeric data package, which is one of a series collected by the Carbon Dioxide Information Center (CDIC).' This technology was developed by various Government and private organizations who contributed it to CDIC for distribution; it did not originate at CDIC. ClDIC is informed that these data have been evaluated by the contributor, and some checking has been done by CDIC. Neither the United States Government, the Department of Energy (DOE), Martin M.arietta Energy Systems, Inc., nor any person acting on behalf of the Department of Energy or Energy Systems, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, usefulness or functioning of any information, data, and related material or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, the Department of Energy, Energy Systems, or any person acting on behalf of the Department of Energy or Energy Systems.

Soil organic C content (SOC, kilograms C per square meter) and its relation to site characteristics are important in evaluating current regional, continental, and global soil C stores and projecting future changes. Data were compiled for 499 pedons in the largely forested, mountainous western Oregon region. The SOC of mineral soil ranged from 0.9 to 24 kg C m-2 (mean = 6.5) for 0-to 20-cm depth and 2.3 to 88 kg C m-2 (mean = 15.8) for 0-to 100-cm depth. Variability in each of the three terms that determine SOC -C concentration, bulk density, and rock volume -contributed substantially to SOC variation. Regression analysis of 134 forest pedons indicated that combinations of site characteristics explained up to 50% of the SOC variability. The SOC increased with annual temperature, annual precipitation, actual evapotranspiration, clay, and available water-holding capacity and decreased with slope. Relations for western Oregon differed qualitatively and quantitatively from those for other regions and contrasted with the decrease in SOC associated with increased temperature in Great Plains grasslands. Of the variability not explained by regression analysis, one-half may be due to the combined uncertainty associated with measurements of C concentrations, bulk density, and rock volume; natural within-site variability; and site-characteristic measurements. Other unexplained variability is probably due to potentially important but poorly documented site characteristics, such as recent vegetation composition, geomorphic disturbance regime, and fire history.

No abstract