Keeton William S, Kraft Clifford E, Warren Dana R
University of Vermont, Rubenstein School of Environment and Natural Resources, 343 Aiken Center, Burlington, Vermont 05405, USA.
Ecol Appl. 2007 Apr;17(3):852-68. doi: 10.1890/06-1172.
Riparian forests regulate linkages between terrestrial and aquatic ecosystems, yet relationships among riparian forest development, stand structure, and stream habitats are poorly understood in many temperate deciduous forest systems. Our research has (1) described structural attributes associated with old-growth riparian forests and (2) assessed linkages between these characteristics and in-stream habitat structure. The 19 study sites were located along predominantly first- and second-order streams in northern hardwood-conifer forests in the Adirondack Mountains of New York (U.S.A.). Sites were classified as mature forest (6 sites), mature with remnant old-growth trees (3 sites), and old-growth (10 sites). Forest-structure attributes were measured over stream channels and at varying distances from each bank. In-stream habitat features such as large woody debris (LWD), pools, and boulders were measured in each stream reach. Forest structure was examined in relation to stand age using multivariate techniques, ANOVA, and linear regression. We investigated linkages between forest structure and stream characteristics using similar methods, preceded by information-theoretic modeling (AIC). Old-growth riparian forest structure is more complex than that found in mature forests and exhibits significantly greater accumulations of aboveground tree biomass, both living and dead. In-stream LWD volumes were significantly (alpha = 0.05) greater at old-growth sites (200 m3/ha) compared to mature sites (34 m3/ha) and were strongly related to the basal area of adjacent forests. In-stream large-log densities correlated strongly with debris-dam densities. AIC models that included large-log density, debris-dam density, boulder density, and bankfull width had the most support for predicting pool density. There were higher proportions of LWD-formed pools relative to boulder-formed pools at old-growth sites as compared to mature sites. Old-growth riparian forests provide in-stream habitat features that have not been widely recognized in eastern North America, representing a potential benefit from late-successional riparian forest management and conservation. Riparian management practices (including buffer delineation and restorative silvicultural approaches) that emphasize development and maintenance of late-successional characteristics are recommended where the associated in-stream effects are desired.
河岸森林调节着陆地和水生生态系统之间的联系，然而，在许多温带落叶林系统中，河岸森林发育、林分结构和溪流栖息地之间的关系却鲜为人知。我们的研究（1）描述了与老龄河岸森林相关的结构属性，（2）评估了这些特征与溪流栖息地结构之间的联系。19个研究地点位于美国纽约阿迪朗达克山脉北部硬木针叶林的主要一级和二级溪流沿岸。这些地点被分类为成熟森林（6个地点）、有残留老龄树木的成熟森林（3个地点）和老龄森林（10个地点）。在溪流河道上方以及距两岸不同距离处测量森林结构属性。在每个溪流河段测量溪流栖息地特征，如大型木质残体（LWD）、水潭和巨石。使用多变量技术、方差分析和线性回归，研究森林结构与林分年龄的关系。我们使用类似方法，并在信息论建模（AIC）之前，研究森林结构与溪流特征之间的联系。老龄河岸森林结构比成熟森林更为复杂，并且地上树木生物量（包括活的和死的）的积累明显更多。与成熟地点（34立方米/公顷）相比，老龄地点（200立方米/公顷）的溪流LWD体积显著更大（α = 0.05），并且与相邻森林的断面积密切相关。溪流中大原木密度与碎屑坝密度密切相关。包含大原木密度、碎屑坝密度、巨石密度和满岸宽度的AIC模型在预测水潭密度方面得到的支持最多。与成熟地点相比，老龄地点由LWD形成的水潭比例高于由巨石形成的水潭。老龄河岸森林提供了北美东部尚未得到广泛认可的溪流栖息地特征，这代表了后期演替河岸森林管理和保护的潜在益处。在希望产生相关溪流效应的地方，建议采用强调后期演替特征的发展和维护的河岸管理实践（包括缓冲区划定和恢复性造林方法）。
