Refining thresholds in coupled fire-vegetation models to improve management of encroaching woody plants in grasslands
Refining thresholds in coupled fire-vegetation models to improve management of encroaching woody plants in grasslands
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DOI：
10.1111/1365-2664.12063
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发表时间：
2013-06
影响因子：
5.7
通讯作者：
D. Twidwell;S. Fuhlendorf;C. Taylor;W. E. Rogers
中科院分区：
文献类型：
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作者：
D. Twidwell;S. Fuhlendorf;C. Taylor;W. E. Rogers
摘要1.在确定恢复优先事项时，通常没有关于如何克服妨碍成功恢复理想生态系统特性和服务的门槛的量化信息。我们试图证明，量化生态阈值，并将其纳入管理为导向的框架提供了一个更全面的视角，阈值的概念可以应用于实现恢复目标。2.作为一个例子，恢复行动在很大程度上是不成功的，根据当时的生态知识，以火灾为基础的阈值在nonresprouting杜松林地。我们建立在以前的阈值为基础的研究和链接完善的模型，从应用火灾物理学与广泛应用的生态正反馈模型的木本植物入侵，引入更全面的了解影响火灾强度和杜松死亡率的机制。3.我们的物理和生态火灾模型的耦合揭示了一个关键的知识差距，缺乏一个定量估计的临界地表火灾强度所需的死亡率的杜松树，这限制了这两个学科的科学知识的联系。4.为了量化火灾强度和J. ashei死亡率之间的关系，我们将先前实验的数据输入到拜拉姆的火线强度模型中。这一临界地表火强度-死亡率阈值估计为Is > 160 kJ m？1 s？1。这个值建立了一个特定的阈值，当管理者试图使用恢复来破坏J. ashei林地时，应该将其作为目标。5.合成与应用。为了使与临界值概念有关的科学信息对从业人员有用，需要有具体的信息来表明如何利用恢复活动来克服临界值，并打破目前的退化状态，以有利于更理想的生态状态。考虑到这一点，我们提出了一个广泛适用的决策支持模型内的状态和过渡框架，确定的生态状态，地表火灾强度死亡率阈值是最有可能满足恢复目标，并提供了燃料的属性，驱动火灾强度应针对恢复超过这个阈值的例子。
Summary 1. Restoration priorities are typically established without quantitative information on how to overcome the thresholds that preclude successful restoration of desirable ecosystem properties and services. We seek to demonstrate that quantifying ecological thresholds and incorporating them into management-oriented frameworks provide a more comprehensive perspective on how the threshold concept can be applied to achieve restoration goals. 2. As an example, restoration actions have been largely unsuccessful when based on prevailing ecological knowledge of fire-based thresholds in nonresprouting Juniperus woodland. We build on previous threshold-based research and link well-established models from applied fire physics with a widely applied ecological positive feedback model of woody plant encroachment to introduce a more comprehensive understanding of the mechanism influencing fire intensity and juniper mortality. 3. Our coupling of physical and ecological fire models revealed a critical knowledge gap, a lack of a quantitative estimate on the critical surface fire intensity required to cause mortality of Juniperus ashei trees, which limits the linking of scientific knowledge from these two disciplines. 4. To quantify the relationship between fire intensity and J. ashei mortality, we input data from a previous experiment into Byram’s fireline intensity model. This critical surface fire intensity–mortality threshold was estimated to be Is > 160 kJ m � 1 s � 1 . This value establishes a specific threshold that managers should target when attempting to use restoration to collapse J. ashei woodlands. 5. Synthesis and applications. For scientific information associated with the threshold concept to be useful to practitioners, specific information is needed that demonstrates how to use restoration activities to overcome thresholds and collapse the current, degraded state in favour of a more desired ecological state. With this in mind, we present a broadly applicable decision support model within a state and transition framework that identifies the ecological states where the surface fire intensity–mortality threshold is most likely to meet restoration objectives and provides examples of how fuel properties that drive fire intensity should be targeted in restoration to surpass this threshold.