Minireviews: Neighborhood Effects, Disturbance Severity, and Community Stability in Forests
Minireviews: Neighborhood Effects, Disturbance Severity, and Community Stability in Forests
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小型评论：邻里效应、干扰严重程度和森林群落稳定性
作者：
L. Frelich;P. Reich
在综合现有研究的基础上，提出了森林树种组成时间稳定性的理论框架和概念模型。该模型主要涉及到几个树的生命周期（几百到几千年）在邻里和立场的空间尺度（0.01-10公顷）的时间段，虽然一些扩展的景观规模也。尖点灾难被选为说明组成动态的立场水平短叶松，北方硬木，白松森林在美国五五大湖和热带雨林在北方亚马逊盆地。该模型具有响应面（后期演替物种的优势度），这取决于两个变量：类型的优势树种和干扰的严重程度的邻里影响。邻里效应是影响物种在干扰时自我替代机会的过程（它们可以是积极的，中性的或消极的），有两种类型：上层-下层效应，如高级繁殖的存在;和干扰激活效应，如有害的种子雨。干扰严重度是指在干扰过程中死亡的树木比例。邻里效应和干扰的严重程度之间的相互作用可以导致间断的稳定性（戏剧性的，但不频繁的变化，在那些森林占主导地位的物种与积极的邻里效应）或演替（连续变化，在那些森林占主导地位的物种与中性-负邻里效应）。我们建议，邻里效应是一个主要的组织因素，在森林动态中，提供了一个链接，跨空间尺度之间的个别树木和干扰/补丁动态的立场和景观尺度。
ABSTRACT A theoretical framework and conceptual model for temporal stability of forest tree-species composition was developed based on a synthesis of existing studies. The model pertains primarily to time periods of several tree lifetimes (several hundred to a few thousand years) at the neighborhood and stand spatial scales (0.01–10 ha), although a few extensions to the landscape scale are also made. The cusp catastrophe was chosen to illustrate compositional dynamics at the stand level for jack pine, northern hardwood, and white pine forests in the Great Lakes Region of the United States and for tropical rainforests in the northern Amazon basin. The models feature a response surface (degree of dominance by late-successional species) that depends on two variables: type of neighborhood effects of the dominant tree species and severity of disturbances. Neighborhood effects are processes that affect the chance of a species replacing itself at the time of disturbance (they can be positive, neutral, or negative) and are of two types: overstory–undestory effects, such as the presence of advanced reproduction; and disturbance-activated effects, such as serotinous seed rain. Disturbance severity is the proportion of trees killed during a disturbance. Interactions between neighborhood effects and disturbance severity can lead to either punctuated stability (dramatic but infrequent change in composition, in those forests dominated by species with positive neighborhood effects) or succession (continuous change, in those forests dominated by species with neutral-negative neighborhood effects). We propose that neighborhood effects are a major organizing factor in forest dynamics that provide a link across spatial scales between individual trees and disturbance/patch dynamics at the stand and landscape scales.