Department of Biological Sciences and Environment and Sustainability Program, University of South Carolina, Columbia, SC, USA.
Adv Mar Biol. 2011;60:123-60. doi: 10.1016/B978-0-12-385529-9.00003-2.
The ongoing and future effects of global climate change on natural and human-managed ecosystems have led to a renewed interest in the concept of ecological thresholds or tipping points. While generalizations such as poleward range shifts serve as a useful heuristic framework to understand the overall ecological impacts of climate change, sophisticated approaches to management require spatially and temporally explicit predictions that move beyond these oversimplified models. Most approaches to studying ecological thresholds in marine ecosystems tend to focus on populations, or on non-linearities in physical drivers. Here we argue that many of the observed thresholds observed at community and ecosystem levels can potentially be explained as the product of non-linearities that occur at three scales: (a) the mechanisms by which individual organisms interact with their ambient habitat, (b) the non-linear relationship between organismal physiological performance and variables such as body temperature and (c) the indirect effects of physiological stress on species interactions such as competition and predation. We explore examples at each of these scales in detail and explain why a failure to consider these non-linearities - many of which can be counterintuitive - can lead to Type II errors (a failure to predict significant ecological responses to climate change). Specifically, we examine why ecological thresholds can occur well before concomitant thresholds in physical drivers are observed, i.e. how even small linear changes in the physical environment can lead to ecological tipping points. We advocate for an integrated framework that combines biophysical, ecological and physiological methods to generate hypotheses that can be tested using experimental manipulation as well as hindcasting and nowcasting of observed change, on a spatially and temporally explicit basis.
全球气候变化对自然和人类管理的生态系统的持续和未来影响，使得人们重新关注生态阈值或临界点的概念。虽然像极向范围转移这样的概括作为理解气候变化对生态总体影响的有用启发式框架，但复杂的管理方法需要超越这些过于简化的模型，进行具有时空明确预测。大多数研究海洋生态系统生态阈值的方法往往侧重于种群，或者侧重于物理驱动因素的非线性。在这里，我们认为在群落和生态系统层面观察到的许多观察到的阈值可能可以解释为三个尺度上发生的非线性的产物：（a）个体生物与其周围栖息地相互作用的机制，（b）生物体生理性能与体温等变量之间的非线性关系，以及（c）生理压力对物种相互作用（如竞争和捕食）的间接影响。我们详细探讨了每个尺度的例子，并解释了为什么不考虑这些非线性（其中许多是违反直觉的）会导致第二类错误（未能预测气候变化对生态系统的重大响应）。具体来说，我们研究了为什么生态阈值可以在物理驱动因素的相应阈值之前发生，即为什么即使是物理环境的微小线性变化也会导致生态临界点。我们提倡一种综合框架，该框架结合了生物物理、生态和生理方法，生成可以通过实验操纵以及对观察到的变化进行回溯和实时预测来检验的假设，具有时空明确性。
