Estimating scale-dependency in disturbance impacts: El Ninos and giant kelp forests in the northeast Pacific
Estimating scale-dependency in disturbance impacts: El Ninos and giant kelp forests in the northeast Pacific
复制标题
DOI：
10.1007/s00442-003-1452-8
复制
发表时间：
2004-02-01
期刊：
影响因子：
2.7
通讯作者：
Edwards, MS
中科院分区：
文献类型：
--
作者：
Edwards, MS
最近关于生态学中尺度问题的讨论强调，在广泛的空间和时间尺度上作用的过程影响生态系统，因此没有合适的单一尺度来研究生态过程。对于发生在广大地理区域并涵盖与生态系统功能有关的各种规模的环境扰动（如厄尔尼诺现象）来说，情况可能尤其如此。然而，通过评估物种丰度和分布的变异模式随规模而发生的变化，或许可以确定生态系统受干扰影响最大的规模，从而提供一种衡量尺度，最清楚地描述干扰的影响。反过来，这可能会产生重要的洞察力的相对重要性的各种强迫因素负责产生这些影响。1997-98年的厄尔尼诺现象是有史以来最强烈的厄尔尼诺现象之一。我研究了这一事件如何影响巨型海带种群在东北太平洋的90个地点，从中部下加利福尼亚，墨西哥到中部加州，美国。这些地点跨越了东北太平洋巨型海带的地理范围，并在厄尔尼诺发生前、发生后立即、发生后几个月、发生后1年多和发生后近2年进行了调查。我使用了一个分层样本设计来比较这些影响在五个空间尺度跨越六个数量级，从几米到超过1,000公里。方差分量分析显示，厄尔尼诺现象将对巨型海带丰度的控制从几米尺度的因素（局部控制）转移到了数百至数千公里的因素（区域控制）。此外，厄尔尼诺现象导致东北太平洋一半的巨型海藻几乎完全消失。厄尔尼诺现象后的巨型海带恢复在多个空间尺度上更为复杂和多变，可能是由这些尺度上的许多因素驱动的。在加州南部，在6个月内恢复了对巨型海带种群的控制，在下加利福尼亚，在2年内恢复了对巨型海带种群的控制。
Recent discussions on scaling issues in ecology have emphasized that processes acting at a wide range of spatial and temporal scales influence ecosystems and thus there is no appropriate single scale at which ecological processes should be studied. This may be particularly true for environmental disturbances (e.g. El Nino) that occur over large geographic areas and encompass a wide range of scales relevant to ecosystem function. However, it may be possible to identify the scale(s) at which ecosystems are most strongly impacted by disturbances, and thus provide a measure by which their impacts can be most clearly described, by assessing scale-dependent changes in the patterns of variability in species abundance and distribution. This, in turn, may yield significant insight into the relative importance of the various forcing factors responsible for generating these impacts. The 1997-98 El Nino was one of the strongest El Ninos ever recorded. I examined how this event impacted giant kelp populations in the northeast Pacific Ocean at 90 sites ranging from central Baja California, Mexico to central California, USA. These sites spanned the geographic range of giant kelp in the Northeast Pacific and were surveyed just before, immediately following, several months after, more than 1 year after, and nearly 2 years after the El Nino. I used a hierarchical sample design to compare these impacts at five spatial scales spanning six orders of magnitude, from a few meters to more than 1,000 km. Variance Components Analyses revealed that the El Nino shifted control over giant kelp abundance from factors acting at the scale of a few meters (local control) to factors operating over hundreds to thousands of kilometers (regional control). Moreover, El Nino resulted in the near-complete loss of all giant kelp throughout one-half of the species' range in the northeast Pacific Ocean. Giant kelp recovery following El Nino was far more complex and variable at multiple spatial scales, presumably driven by numerous factors acting at those scales. Recovery returned local control of giant kelp populations within 6 months in southern California, and within 2 years in Baja California.