Regional carbon dynamics in the southeastern U.S. coastal plain: Balancing land cover type, timber harvesting, fire, and environmental variation

Abstract

[1] Understanding regional carbon budgets is a leading issue in carbon cycling research, but issues of measurement difficulty, scale, boundaries, and logistics compromise estimates at areas larger than stands or research plots. We studied four 15 Â 15 km sample areas to examine land management and wildfire effects on carbon storage dynamics in the forested southeastern U.S. coastal plain region from 1975 to 2001. Carbon exchange and storage rates were estimated using satellite remote-sensing methods coupled with micrometeorological and biomass measurements. Carbon losses occurred by timber harvesting and fire, and carbon release continued for four years following clearing, suppressing landscape carbon gain proportional to the cleared area. Carbon accumulated at an average rate of 90,000 t C yr À1 in the landscape (total area 900 km 2 ) from 1975-2000, or $1 t C ha À1 yr À1 . Interannual variation was related mainly to the magnitude of annual plantation timber harvesting. Wildfires were rare and their effects on carbon balances consequently small, despite having large local impact. Previous studies in the area demonstrated that environmental fluctuations had little direct effect on the net landscape exchange of carbon, although indirect effects included higher probability of fire during droughts and shifts in harvesting to drier sites during wet periods. Although this study was a simple aggregation of carbon cycle components from fine spatial scale (Landsat images) to the landscape, the extrapolation incorporated important spatial and temporal environmental heterogeneities and led to the unexpected suggestion that the industrial forests of the southeast U.S. Coastal plain are a long-term carbon sink. The analysis also revealed specific uncertainties in our scaling efforts that point to future research needs.Citation: Binford, M. W., H. L. Gholz, G. Starr, and T. A. Martin (2006), Regional carbon dynamics in the southeastern U.S. coastal plain: Balancing land cover type, timber harvesting, fire, and environmental variation,

Invasive insects impact forest carbon dynamics

“…Catastrophic disturbance typically involves severe perturbations to hydrologic and nutrient cycles, in addition to loss of C from long-term storage pools in tree boles, forest floor, and soil. Recovery of positive C gain may require 5 or more years (Thornton et al, 2002;Binford et al, 2006;Humphreys et al, 2006). Recovery of long-term storage pools of C in stem biomass, forest floor, and soil following catastrophic disturbance may take millennia in some forests.…”

Impacts of disturbance history on forest carbon stocks and fluxes: Merging satellite disturbance mapping with forest inventory data in a carbon cycle model framework

“…This record is of great value for regional to continental assessments of forest change. For example, Landsat imagery has been used to construct maps of forest age for single scenes (approximately 180 × 180 km each) (Binford, Gholz, Starr, & Martin, 2006;Masek & Collatz, 2006) or even an entire region such as Oregon-California, (Law et al, 2004;Turner et al, 2007). This prior work identified challenges from low accuracy of mapped stand age and also offered too small a sample to quantify US or North American rates of change.…”

Contrasting effects of invasive insects and fire on ecosystem water use efficiency

“…The relatively high variability in nighttime NEE and annual R eco contrasts somewhat with results reported from other disturbed forests on the Atlantic coastal plain (e.g., Amiro et al, 2010). For example, following clearcutting of a slash pine plantation in N. Florida, variation in R eco was only 304 g C m −2 yr −1 pre-and post-harvest, representing a coefficient of variation of 14 % of mean annual values, despite major changes in biomass and detrital pools on the forest floor and soil disturbance associated with site preparation (Clark et al, 2004;Binford et al, 2006).…”