Natural Resource Ecology and Management, Oklahoma State University, 008C AGH, Stillwater, OK 74078, USA.
Conserv Biol. 2009 Jun;23(3):588-98. doi: 10.1111/j.1523-1739.2008.01139.x. Epub 2008 Dec 16.
Our understanding of fire and grazing is largely based on small-scale experimental studies in which treatments are uniformly applied to experimental units that are considered homogenous. Any discussion of an interaction between fire and grazing is usually based on a statistical approach that ignores the spatial and temporal interactions on complex landscapes. We propose a new focus on the ecological interaction of fire and grazing in which each disturbance is spatially and temporally dependent on the other and results in a landscape where disturbance is best described as a shifting mosaic (a landscape with patches that vary with time since disturbance) that is critical to ecological structure and function of many ecosystems. We call this spatiotemporal interaction pyric herbivory (literal interpretation means grazing driven by fire). Pyric herbivory is the spatial and temporal interaction of fire and grazing, where positive and negative feedbacks promote a shifting pattern of disturbance across the landscape. We present data we collected from the Tallgrass Prairie Preserve in the southern Great Plains of North America that demonstrates that the interaction between free-roaming bison (Bison bison) and random fires promotes heterogeneity and provides the foundation for biological diversity and ecosystem function of North American and African grasslands. This study is different from other studies of fire and grazing because the fires we examined were random and grazing animals were free to roam and select from burned and unburned patches. For ecosystems across the globe with a long history of fire and grazing, pyric herbivory with any grazing herbivore is likely more effective at restoring evolutionary disturbance patterns than a focus on restoring any large vertebrate while ignoring the interaction with fire and other disturbances.
我们对火和放牧的理解主要基于小规模的实验研究，在这些研究中，处理方法均匀地应用于被认为同质的实验单元。任何关于火和放牧相互作用的讨论通常都是基于一种忽略复杂景观中空间和时间相互作用的统计方法。我们提出了一个新的重点，即关注火和放牧的生态相互作用，其中每个干扰在空间和时间上都依赖于另一个干扰，并导致干扰最好被描述为一个不断变化的镶嵌体（一个随着干扰后时间的推移而变化的斑块景观）的景观，这对许多生态系统的生态结构和功能至关重要。我们称这种时空相互作用为火驱食草（字面意思是火驱动的放牧）。火驱食草是火和放牧的空间和时间相互作用，其中正反馈和负反馈促进了景观上干扰的变化模式。我们展示了从北美大平原南部的高草草原保护区收集的数据，这些数据表明，自由漫游的野牛（Bison bison）和随机火灾之间的相互作用促进了异质性，并为北美和非洲草原的生物多样性和生态系统功能提供了基础。这项研究与其他火和放牧研究不同，因为我们研究的火灾是随机的，放牧动物可以自由漫游并从燃烧和未燃烧的斑块中进行选择。对于在火和放牧方面有着悠久历史的全球生态系统来说，任何食草动物的火驱食草都比专注于恢复任何大型脊椎动物而忽略与火和其他干扰的相互作用更有效地恢复进化干扰模式。
