Most Hawaiian forests lack resiliency following disturbance due to the presence of non‐native and invasive plant and animal species. The montane wet forest within Hakalau Forest National Wildlife Refuge on Hawai'i island has a long history of ungulate disturbance but portions of the refuge were fenced and most ungulates excluded by the early 1990s. We examined patterns of regeneration within two 100 ha study sites in this forest following the removal of ungulates and in the absence of invasive woody tree species to determine, in part, if passive restoration techniques can be successful under these conditions. We characterized growth, mortality, and basal area (BA) changes for approximately 7,100 marked individuals of all native tree species present in two surveys over a 17–18‐year period within two hundred 30 m diameter forest plots. Considerable recruitment within plots of new trees of all species significantly changed size class distributions and erased deficits in small‐sized trees observed during the first survey, particularly for the codominant canopy tree, koa (Acacia koa). Overall, growth of established dominant 'ōhi'a trees (Metrosideros polymorpha) and recruitment of mid‐canopy trees contributed to increases in BA while high levels of mortality for large A. koa trees contributed to decreased BA. This resulted in a slight increase in BA between the two surveys (+1.9%). This study demonstrates that fencing and ungulate removal may have rescued the A. koa population by facilitating the first real pulse in recruitment in over a century, and that passive restoration can be a successful management strategy in this forest.

中文翻译：

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在夏威夷山地湿林中除去有蹄类动物后的森林更新

由于存在非本地和入侵的动植物物种，大多数夏威夷森林在受到干扰后缺乏复原力。夏威夷岛的哈卡劳森林国家野生动物保护区内的山地湿润森林有蹄类动物有悠久的历史，但避难所的一部分被围起来，大部分有蹄类动物在1990年代初期被排除在外。在去除有蹄类动物和没有侵入性木本树种之后，我们检查了该森林中两个100公顷研究地点的再生模式，以部分确定在这些条件下被动恢复技术能否成功。我们在直径为100米，直径30 m的200个林地中，在17-18年的两次调查中，对所有大约7100种有标记的所有本地树种的生长，死亡率和基底面积（BA）的变化进行了特征描述。金合欢（Acacia koa）。总体而言，已建立的优势'ōhi'a树（Metrosideros polymorpha）的生长和中冠层树的募集导致BA的增加，而大型A的死亡率很高。Koa树导致BA降低。这导致两次调查之间的BA略有增加（+ 1.9％）。这项研究表明，击剑和有蹄类动物去除可能挽救了一个。通过促进一个多世纪以来招募的第一批真正人潮而形成的Koa种群，并且被动恢复可以是该森林中成功的管理策略。