资源环境科技发展态势分析平台

A long-term forest management case study on the Fernow Experimental Forest in West Virginia referred to as the Cutting Practice Level study is evaluated after 60 years. Treatments include a commercial clearcut (one time application), a 39 cm diameter-limit (applied 4 times), uneven-aged management using two variations of single-tree selection (applied 7 and 8 times, respectively), and an unmanaged reference area. We examine productivity, species composition and diversity, structure, tree quality, and revenues generated related to each treatment since establishment. The diameter-limit treatment resulted in greatest average periodic annual increment (PAI) of sawtimber volume of 3.1 m(3) ha(-1) yr(-1) while the unmanaged reference area resulted in the least of 2.2 m(3) ha(-1) yr(-1) (based on the difference in standing volume from 1956 to 2008). All types of partial harvesting resulted in greater sawtimber productivity than either the commercial clearcut or the reference area. Post-harvest tree quality, as measured by proportion of grade 1 butt logs, has improved from 1988 to 2008 for all but the diameter-limit treatment, which is similar to conditions in 1968. In 2008, the proportion of grade 1 trees in the residual stand ranged from a high of 0.22 for single-tree selection to 0.15 for diameter-limit harvesting. Species composition is becoming less diverse and more dominated by shade-tolerant species in all treatment groups but the change has been the greatest in the two single-tree selection treatments. Initially, size-class distributions were somewhat unimodal and reflective of even-aged stands with shade tolerant species persisting in the understory. In 2008, the single-tree selection treatments were both characterized by a reverse-J size class distribution and it appears this structure can be maintained due to recruitment of shade-tolerant species in the smaller size classes with concomitant reductions in species diversity. The net present value for each treatment in 2008, the time of the last management intervention, ranged from $20,000 ha(-1) for reference area to almost $34,000 ha(-1) for the single-tree selection treatment that included management of pole-sized trees based on all revenue and the value of standing timber using an internal rate of return of 4%. Published by Elsevier B.V.