title: Development of a protocol for monitoring status and trends in forest soil carbon at a national level.
abstract: The national Forest Health Monitoring (FHM) program requires protocols for monitoring soil carbon contents. In a pilot study, 30 FHM plots loblolly shortleaf (Pinus taeda L./Pinus echinata Mill.) pine forests across Georgia were sampled by horizon and by depth increments. For total soil carbon, approximately 40% of the variance was between plots, 40% between subplots and 20% within subplots. Results by depth differed from those obtained by horizon primarily due to the rapid changes in carbon content from the top to the bottom of the A horizon. Published soil survey information overestimated bulk densities for these forest sites. The measurement of forest floor depths as a substitute to sampling did not provide reliable estimates of forest floor carbon. Precision of replicate samples was approximately 10-30% for field duplicates and 5-10% for laboratory duplicates. Based on national indicator evaluation criteria, sampling by depth using bulk density core samplers has been recommended for national implementation. Additional procedures are needed when sampling organic soils or soils with a high percentage of large rock fragments.
authors.affiliation: Harry Reid Center, University of Nevada, Las Vegas 89154-4009, USA. palmerc@unlv.edu
authors.forename: C J
authors.initials: CJ
authors.lastname: Palmer
authors.forename: W D
authors.initials: WD
authors.lastname: Smith
authors.forename: B L
authors.initials: BL
authors.lastname: Conkling
mesh_terms: D002244:Carbon / Q000032:analysis*; D003625:Data Collection; D004784:Environmental Monitoring / Q000379:methods* / Q000592:standards*; D028223:Pinus / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D015203:Reproducibility of Results; D012987:Soil; D013048:Specimen Handling; D014197:Trees; D014481:United States
chemical_list: D012987:Soil; D002244:Carbon