Forest harvest residue (FHR) is an important environmental component, but how do you measure it? The recent surge and interest in renewable energy in the U.S., including wood energy, has brought growing concern about the impact of biomass removal and its impact on biodiversity, water quality and long-term site productivity. This document will describe how to rapidly inventory scattered and piled FHR.
To inform the dialogue on sustainability, the NC State University Extension-Forestry established a sampling study to characterize logger utilization and residual woody biomass across the state. Study sites covered all physiographic regions of North Carolina. On study sites prism sweeps for woody biomass (Bebber and Thomas, 2003) were used to quickly estimate wood residues left after harvesting. Estimated woody biomass residues were compared with scale ticket information from loggers, consultants and timber buyers. Logger utilization was developed using these collected data.
Prism sweep and line intercept methods were compared for accuracy and efficiency to measure woody biomass residues on a recently harvested site in Eastern North Carolina. A 100% tally control on 0.1 acre plots was used to compare volume estimates of tested methods. Estimates of residual volume were accurate and not significantly different. Prism sweeps required an average of three minutes per plot, whereas line intersect samples averaged seventeen minutes per plot. Prism sweeps were accurate and five times more efficient than line intersect samples.