Residual Timber Values within Piedmont Streamside Management Zones of Different Widths and Harvest Levels

摘要

Forested streamside management zones (SMZs) provide numerous societal benefits including protection of water quality and enhancement of in-stream and riparian habitats. However, values of residual timber in SMZs are often ignored, yet maintenance of unnecessarily wide SMZs can potentially reduce merchantable timber. Therefore, forestland owners, managers, and logging contractors are interested in determining minimum SMZ widths and stocking levels that can effectively maintain water quality while minimizing residual SMZ stand values. A larger SMZ efficacy study evaluated the efficacy of 7.6-m SMZs with no thinning, 15.2-m SMZs with no thinning, 15.2-m SMZs with thinning, and 30.2-m SMZs without thinning within 16 operational clearcuts. All SMZs widths provided effective sediment control (Lakel et al. 2010). The substudy presented here evaluated residual values in the SMZs of the larger study. Analyses examined immediate values associated with foregoing removal of SMZ timber and provide insight into future SMZ management issues. Across 16 harvested tracts, SMZs accounted for approximately 12% of the total harvest area with an average SMZ residual timber value of $1,064.78/ha. This study supports the financial benefits of partial harvests within the SMZs that remove higher value trees as typically recommended or permitted by best management practice guidelines. However, partial harvests may promote less valuable shade-tolerant species. Results also indicated that almost one-half of the SMZs had notable wind and/or ice damage within 2 years of installation. Financial analysis including opportunities for a tax credit indicate that longer term management of SMZs may be financially feasible if valuable products continue to be thinned from these stands along with rotational harvesting of the adjacent upland stands. Overall, results indicate that society and landowner short-term goals for typical southern Piedmont sites can generally be achieved by leaving 15.2-m SMZs and thinning the stands where practical.