Disturbances are one of the most important processes affecting natural systems, but there is a gap between simple conceptual models of disturbance and complex empirical studies. We studied the perturbation caused by headward-eroding creeks in southeastern USA salt marshes. We measured disturbance responses (magnitude and recovery trajectory) of 19 variables. Some variables (shoot density, root biomass, snail density, soil pH, soil strength, soil temperature, elevation) declined sharply, while other variables (crab burrow density, soil organic matter, soil redox) increased sharply, in response to the burrowed and grazed conditions at the creek head. These variables recovered over subsequent years or decades. Other variables (shoot height, aboveground biomass, rhizome biomass, light interception) declined sharply in the creek head, then overshot control values before recovering. Some variables (benthic algae, soil salinity) did not appear to be disturbed by the creek head. As hypothesized, plants recovered before soils and snails. Disturbance magnitude and time to recovery were often greater directly adjacent to the new creekbank than for the same variables in a parallel transect further away from the creekbank, and in some cases variables never converged with control values, indicating a persistent state change. Reducing the dimensionality of the data set into principal component axes obscured the diverse ways in which different aspects of the system responded to and recovered from the perturbation. Our study illustrates the challenges in moving from simple conceptual models of disturbance to empirical studies in which multiple variables are likely to be affected differently and follow different recovery trajectories.

中文翻译：

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扰动很复杂：向前侵蚀的盐沼小溪会产生多种反应和恢复轨迹

扰动是影响自然系统的最重要过程之一，但简单的扰动概念模型与复杂的实证研究之间存在差距。我们研究了美国东南部盐沼中由水流侵蚀引起的扰动。我们测量了 19 个变量的干扰响应（幅度和恢复轨迹）。一些变量（枝条密度、根生物量、蜗牛密度、土壤 pH 值、土壤强度、土壤温度、海拔）急剧下降，而其他变量（蟹穴密度、土壤有机质、土壤氧化还原）急剧增加，以响应洞穴和小溪头的放牧条件。这些变量在随后的几年或几十年中恢复了。其他变量（枝高、地上生物量、根茎生物量、截光率）在溪头急剧下降，然后在恢复之前超过控制值。一些变量（底栖藻类、土壤盐度）似乎没有受到溪头的干扰。正如假设的那样，植物在土壤和蜗牛之前恢复。与新河岸直接相邻的扰动幅度和恢复时间通常大于远离河岸的平行样带中的相同变量，并且在某些情况下，变量从未与控制值收敛，表明状态持续变化。将数据集的维度降低到主成分轴上，模糊了系统不同方面响应扰动并从扰动中恢复的不同方式。