Tree microhabitat structures as indicators of biodiversity in Douglas-fir forests of different stand ages and management histories in the Pacific Northwest, U.S.A.
Tree microhabitat structures as indicators of biodiversity in Douglas-fir forests of different stand ages and management histories in the Pacific Northwest, U.S.A.
复制标题
树木微生境结构作为美国太平洋西北地区不同林龄和管理历史花旗松森林生物多样性的指标
DOI：
10.1016/j.foreco.2008.11.027
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发表时间：
2009
影响因子：
3.7
通讯作者：
S. Winter
中科院分区：
文献类型：
--
作者：
Alexa K. Michel;S. Winter
森林生态系统结构复杂性对生态系统多样性的重要性已得到广泛认识。然而，作为生物多样性指标的树木微生境结构却很少成为多样性研究的重点，尽管其发生与森林物种丰富度和生态系统功能高度相关。本研究对孟氏杉木（pseudosuga menziesii）林的微生境结构进行了定义，并比较了自然林分和不同主动经营历史和林龄林分中微生境的频率和丰度。确定了天然森林的指示微生境结构，分析了微生境结构丰度与道格拉斯冷杉树径的关系。所调查的大多数微生境确实是自然成熟和自然老林分的指示物，如：折断的树梢、卡口顶、裂纹或疤痕、树皮脱落、空心室、腐烂的茎腔、腐烂和不腐烂的树皮袋、树皮碗、瘤、重树脂病和树皮破裂。胸径20.0 ~ 40.0cm的道格拉斯冷杉以树脂滴状和重树脂沉积为主，而胸径80.0cm的道格拉斯冷杉以树皮碗状结构、树皮袋状结构和带腐烂的树皮袋状结构为主。管理历史（包括未对自然林分进行处理）和林龄决定了林分微生境丰度和微生境组成。观察到的微生境变异性在多年未采伐或以其他方式造林的林分（低处理历史）和自然林分中最高，在最近管理的林分中最低。新管理林分平均有115个微生境/ha，低处理史林分平均有520个微生境/ha，自然成熟林和自然老林分平均有745个微生境/ha。如果目标是在均匀树龄的道格拉斯冷杉林分中为各种生物和生态系统功能创造结构复杂性，那么对经过造林处理的林分中的微生境进行主动管理是很重要的。尽管在生物多样性和经济目标方面，微生境的管理似乎经常是冲突的，但我们建议采取造林措施，以减少目前森林林分的同质化，而木材产量的损失相对较小，特别是如果将减少的木材产量与预期的长期社会、经济和生态效益进行比较。然而，根据华盛顿州西部和俄勒冈州道格拉斯冷杉原生林的临时最低标准，可能需要几十年的时间才能获得接近原生林标准的林分。
The importance of structural complexity in forest ecosystems for ecosystem diversity has been widely acknowledged. Tree microhabitat structures as indicators of biodiversity, however, have only seldom been the focus of diversity research although their occurrence is highly correlated with the abundance of forest species and ecosystem functions. In this study, microhabitat structures in Douglas-fir (Pseudotsuga menziesii) forests were defined and their frequency and abundance in natural stands and stands of varying active management histories and stand ages was compared. Indicator microhabitat structures for natural forests were determined and the relationship of the abundance of microhabitat structures with tree diameter of Douglas-fir trees was analysed. Most of the investigated microhabitats are indeed indicators of natural mature and natural old-growth stands, e.g., broken tree top, bayonet top, crack or scar, bark loss, hollow chamber, stem cavity with decay, bark pocket with and without decay, bark bowl, burl, heavy resinosis, and bark burst. In Douglas-fir trees, resin drops and heavy resinosis were the dominant microhabitats in trees with >20.0–40.0cm diameter at breast height (dbh), whereas bark structures such as bowls in the bark, bark pockets, and bark pockets with decay were the most abundant microhabitats in Douglas-fir trees >80.0cm. Both management history (including no treatment in natural stands) and stand age determined the abundance of microhabitats and microhabitat composition of stands in our study. The observed microhabitat variability was highest in stands that had not been harvested or otherwise treated silviculturally in many years (low treatment history) and the natural stands and lowest in the recently managed stands. Recently managed stands had, on average, 115 microhabitats/ha, stands with a low treatment history had 520 microhabitats/ha, and natural mature and natural old-growth stands had 745 microhabitats/ha. Active management for microhabitats in silviculturally-treated stands is important if the aim is to create structural complexity for a variety of organisms and ecosystem functions in even-aged Douglas-fir stands. Although the management of microhabitats with respect to biodiversity and economic objectives often seem to be in conflict, we suggest silvicultural measures to reduce the current homogenization of forest stands with relatively minor losses of wood production especially if the reduced timber output is compared with the expected longterm social, economic, and ecological benefits. It may, however, take many decades to obtain stands that approximate the criteria for old-growth according to the interim minimum standards for old-growth Douglas-fir forests in their native western Washington and Oregon.