Landscape level differences in soil carbon and nitrogen: implications for soil carbon sequestration

Journal Article · Sun Dec 01 04:00:00 EST 2002 · Global Biogeochemical Cycles

DOI:https://doi.org/10.1029/2002GB001918· OSTI ID:989638

Garten, Jr, Charles T ^[1]; Ashwood, Tom L ^[1]

---

1. ORNL

The objective of this research was to understand how land cover and topography act, independently or together, as determinants of soil carbon and nitrogen storage over a complex terrain. Such information could help to direct land management for the purpose of carbon sequestration. Soils were sampled under different land covers and at different topographic positions on the mostly forested 14,000 ha Oak Ridge Reservation in Tennessee, USA. Most of the soil carbon stock, to a 40-cm soil depth, was found to reside in the surface 20 cm of mineral soil. Surface soil carbon and nitrogen stocks were partitioned into particulate ({ge}53 {micro}m) and mineral-associated organic matter (<53 {micro}m). Generally, soils under pasture had greater nitrogen availability, greater carbon and nitrogen stocks, and lower C:N ratios than soils under transitional vegetation and forests. The effects of topography were usually secondary to those of land cover. Because of greater soil carbon stocks, and greater allocation of soil carbon to mineral-associated organic matter (a long-term pool), we conclude that soil carbon sequestration, but not necessarily total ecosystem carbon storage, is greater under pastures than under forests. The implications of landscape-level variation in soil carbon and nitrogen for carbon sequestration are discussed at several different levels: (1) nitrogen limitations to soil carbon storage; (2) controls on soil carbon turnover as a result of litter chemistry and soil carbon partitioning; (3) residual effects of past land use history; and (4) statistical limitations to the quantification of soil carbon stocks.

• Research Organization: Oak Ridge National Laboratory (ORNL); Oak Ridge National Environmental Research Park
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 989638
• Journal Information: Global Biogeochemical Cycles, Journal Name: Global Biogeochemical Cycles Journal Issue: 4 Vol. 16; ISSN 0886-6236
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CARBON
CARBON SEQUESTRATION
CHEMISTRY
COMPLEX TERRAIN
ECOSYSTEMS
FORESTS
LAND USE
MANAGEMENT
NITROGEN
OAK RIDGE RESERVATION
ORGANIC MATTER
PARTICULATES
PASTURES
PLANTS
SOILS
STORAGE
TENNESSEE
TOPOGRAPHY