Predicting Physical Disturbance in a Changing Environment: The Effect of Spatial and Temporal Scale

预测变化环境中的物理干扰：时空尺度的影响

• 批准号: 9985946
• 负责人: Mark Denny
• 金额: $ 54.98万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-10-01 至 2006-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9985946&HistoricalAwards=false
• 关键词: Predicting; Physical; Disturbance; Changing; Environment

Current ideas regarding the roles of competition, predation, recruitment, succession, and disturbance in community ecology are based in part on experiments in the intertidal zone of wave-swept rocky shores, and these studies serve as benchmarks for the ability of ecological theory to make predictions about the real world. Much of the experimental utility of the shore is due to the rapid turnover of individuals in the community. On exposed shores where turnover is due primarily to environmental effects, the ultimate ability to predict the distribution and abundance of organisms rests on our proximal ability to predict the physical environment at all relevant spatial and temporal scales, and on our ability to account for the biological consequences of environmental stress.Field experiments have shown that it is feasible to predict from offshore wave height the maximum wave forces imposed at a given location on the shore. However, these forces (an important environmental stress) vary substantially through both space and time in a pattern known as 1/f-noise: the larger the spatial or temporal scale at which the shore is examined, the larger the variation measured. As a result, it is difficult to specify unambiguously the wave exposure of a site. Because many aspects of intertidal community dynamics are closely tied to wave exposure, the 1/f-noise characteristic of the shore becomes potentially problematic when an attempt is made to generalize ("scale up") the results of small-scale experiments. Preliminary measurements of species diversity suggest, however, that it is possible for plants and animals to interact with the physical environment in a fashion that produces well-defined spatial structure even in the presence of physical 1/f-noise. This project builds on these results by examining how several basic ecological processes (e.g., recruitment, growth, and predation intensity) vary across spatial and temporal scales, and how these scales contribute to the overall pattern in community dynamics.Field experiments will be conducted along a horizontal transect in the intertidal zone for which previous work has characterized the spatial variation in maximum wave-induced force and maximum temperature. Simultaneous measurements will be made at 2-m intervals along a 200-m transect of: the rate of recruitment of mussels and barnacles, the rate of growth of mussels and barnacles, the intensity of gastropod predation on barnacles, disturbance in the mussel bed, and the course of succession on previously unoccupied substratum. Quarterly measurements will be made of species abundances at each location, and from these species diversity is calculated at each of the 100 points on the transect. Because these measurements are made at equally spaced points, it is possible to use spectral analysis to examine the scale-specific cross-correlation between the variation in each ecological process or biological attribute and the co-occurring variation of the physical environment (wave force and temperature). In conjunction with the experiment on predation intensity, measurements will be made of the adhesive tenacity and foraging speed of the primary gastropod predators of barnacles (Nucella and Acanthina). These field experiments will provide a direct measure of whether there are defined scales for ecological processes, and (if so) how biology interacts with environmental 1/f-noise to yield the relevant scale(s) of community dynamics.In addition to exploring the spatial and temporal variation in wave forces, previous work has shown that maximum wave-induced forces on the shore correspond to water velocities that are approximately twice those predicted by standard theories of wave breaking. The cause of these extreme velocities (up to 25 m/s) is thought to be tied to the interaction of breaking waves with the complex topography of the rocky shore. For example, when breaking waves are refracted so that two wave fronts collide, a jet of water is produced the velocity of which is substantially greater than that of either wave. Experiments will be conducted in a laboratory wave tank to characterize the flows resulting when waves break on a variety of model shores, thereby to delineate the circumstances under which enhanced velocities can be expected. In conjunction with these experiments measurements will be made of the force exerted on objects held fixed to the substratum. These measurements (in addition to similar measurements conducted in the field) will be used to test the possibility that the apparently extreme water velocities calculated from force measurements are in fact an artifact of the manner in which the leading edge of a wave impacts plants and animals on the shore. This work will allow one to quantify for the first time the inherent spatial and temporal scales of processes that govern community dynamics on wave-swept shores, and thereby to forge mechanistic links among the wave "weather," the shoreline topography, and the processes of recruitment, growth, predation, and succession. The elucidation of these mechanisms represents an important first step toward an ability to make large-scale mechanistic predictions from small-scale interactions, predictions that may be important inputs into the appropriate design of coastal marine protected areas.

目前关于竞争、捕食、补充、演替和干扰在群落生态学中的作用的观点，部分是基于在波浪冲刷的岩石海岸的潮间带的实验，这些研究作为生态理论预测真实的世界的能力的基准。海岸的许多实验性效用是由于群落中个体的快速更替。在暴露的海岸，营业额主要是由于环境的影响，预测生物的分布和丰度的最终能力取决于我们在所有相关的空间和时间尺度上预测物理环境的能力，现场试验表明，根据离岸波高预测最大波浪力是可行的，施加在海岸上的给定位置。然而，这些力（一种重要的环境压力）在空间和时间上都有很大的变化，其模式被称为1/f噪声：海岸的空间或时间尺度越大，测量到的变化就越大。因此，很难明确地指定一个站点的波浪暴露。由于潮间带群落动力学的许多方面与波浪暴露密切相关，因此当试图概括（“按比例放大”）小规模实验的结果时，海岸的1/f噪声特性可能会出现问题。然而，对物种多样性的初步测量表明，即使存在物理1/f噪声，植物和动物也有可能以一种产生明确空间结构的方式与物理环境相互作用。该项目建立在这些结果的基础上，通过研究几个基本的生态过程（例如，补充，增长和捕食强度）的变化，以及这些尺度如何有助于在群落动态的整体格局。现场实验将进行沿着水平样带在潮间带，以前的工作特点的空间变化的最大波浪诱导力和最高温度。同时测量将在2米的间隔沿着一个200米的样带：贻贝和藤壶的招聘率，贻贝和藤壶的增长率，腹足类捕食藤壶的强度，在贻贝床的干扰，以及在以前无人居住的底层的继承过程。每季度将对每个地点的物种丰度进行测量，并根据这些数据计算样带上100个点的物种多样性。由于这些测量是在等距点进行的，因此可以使用谱分析来检查每个生态过程或生物属性的变化与物理环境（波浪力和温度）的共同发生的变化之间的尺度特定的互相关。结合捕食强度的实验，将测量藤壶的主要腹足类捕食者（Nucella和Cordina）的粘附强度和觅食速度。这些野外实验将提供一个直接的测量方法，以确定生态过程是否有确定的尺度，以及（如果有）生物如何与环境1/f噪声相互作用，以产生群落动态的相关尺度。除了探索波浪力的空间和时间变化外，以前的工作表明，最大波-海岸上的诱导力对应于大约两倍于由波浪破碎的标准理论预测的水速度。这些极端速度（高达25 m/s）的原因被认为与破碎波与岩石海岸复杂地形的相互作用有关。例如，当破碎的波浪被折射，使得两个波前碰撞时，会产生一股水流，其速度基本上大于任何一个波浪的速度。将在实验室波浪水槽中进行实验，以表征波浪在各种模型海岸上破碎时产生的流动，从而描绘出预期速度增加的情况。结合这些实验，将测量施加在固定在底层的物体上的力。这些测量（除了在现场进行的类似测量之外）将用于测试根据力测量计算的明显极端水速度实际上是波浪前缘影响海岸上的植物和动物的方式的人为因素的可能性。这项工作将允许一个量化的内在的空间和时间尺度的过程中，管理社区动态波扫海岸，从而建立机械波“天气”之间的联系，海岸线地形，招聘，增长，捕食和继承的过程。阐明这些机制是朝着从小规模相互作用作出大规模机制预测的能力迈出的重要的第一步，这些预测可能是适当设计沿海海洋保护区的重要投入。