Development of Tree and Understory Vegetation in Young Douglas-Fir Plantations in Western Oregon

摘要: The prevalence of young even-aged Douglas-fir (Pseudotsuga menziesii) stands in Oregon and Washington has led to concerns about a landscape being dominated by the stem exclusion phase. In this context, our study documented development two aspects important for diversity plant wildlife habitat: tree characteristics understory vegetation. Using chronosequence approach, we measured conditions 39 plantations ranging from 6 20 years. Results confirmed intuitive trends, but quantification indicated that some these trends develop earlier than commonly assumed. Tree growth was positively related stand density, trend reversed fairly early. Crown were influenced very early indicating maintaining long-lived crown typical can only be accomplished lowering density through precommercial thinning. Understory herb cover reduced throughout time, while shrub increased. Species compositions quite complex, with an initial strong presence invader species later dominance usually associated mature forests; however, there many exceptions successional still present after showed stage is dynamics vary different characteristics, finer resolution initiation may warranted plantations. West. J. Appl. For. 21(2):94–101.