Uneven-Aged Management: Panacea, Viable Alternative, or Component of a Grander Strategy?

摘要

Alternatives to intensive, even-aged plantation management are motivated by the wide range of values that people place on forests. Continuous forest cover maintained by uneven-age silvicul-tural systems may, for example, enhance late scral wildlife habitat, protect soil from erosion, or maintain aesthetic quality. Implicit in the search for alternative silvtcultural systems, however, is continued interest in timber extraction. Accommodating other resource values while generating timber revenue is assumed to entail a cost through loss in timber production in most situations. Debates rage on, however, about the relative productivity or even-age versus uneven-age silvicultural systems. To set the context for debates about relative productivity, two issues must first be addressed. First, both systems can be managed on an intensive basis, and many professional foresters would even argue that uneven-age management must be intensive to be successful. In most forest types, including Douglas-fir (Pseudotsuga menziesii), natural stand dynamics and disturbance regimes do not move stands to an uneven-aged condition, so continuous intervention is necessary to maintain this condition. Second, many stand structures and sequences of stand structures characterizethe uneven-aged condition, but Intensive management is necessary to achieve the more limited set of structural options that optimize the system's productive potential. Relative productivity must therefore be best considered in the context of a common intensity of management, so that management intensity is not confounded with silvicultural system.