Fire and Landscape Change in Northern Patagonia, Argentina: Integrating Landscape Heterogeneity, Land Use, and Climatic Variability

在全球气候变化和人类对自然景观影响增加的背景下，火灾发生率的增加可能是森林生态系统广泛变化的一个主要原因。虽然人们对短期天气条件如何影响火灾发生的可能性及其强度了解甚多，但对土地利用的历史和景观的异质性如何影响火灾蔓延的方式和生态系统对火灾的反应了解甚少。通过对阿根廷巴塔哥尼亚北部的多尺度研究，该项目将解决以下关键问题：(1)过去两个世纪以来，火灾和其他形式的干扰导致的景观异质性如何影响火灾的蔓延以及随后火灾后植被和燃料的变化？(2)气候条件对火灾后植被恢复，特别是树木更新的影响是什么？(3)牲畜和其他形式的土地利用对火灾后植被和燃料恢复的关键早期阶段有什么影响？这三个问题将通过一种综合的多尺度方法来研究植被动态和景观生态学，这些方法涉及从干灌木地到湿森林的一系列生态系统类型。研究人员将把基于历史航空照片和卫星图像的植被和火灾模式的大尺度空间分析与基于树木年轮样本的扰动历史的详细实地研究结合起来。这些方法将与家畜对水分有效性和草食性的实验操作相结合，模拟气候变化和土地利用对火灾后植被恢复的影响。这项研究将推动1985年开始的一项长期研究计划，重点关注自然干扰、气候变化和人类活动已经并将继续改变巴塔哥尼亚北部景观的过程。预期的结果将量化火灾行为和对景观异质性的影响在空间和时间尺度上的关系，对资源管理者有用。研究结果也将为空间景观模型在该景观中预测火灾行为和火灾效应的实际应用提供强有力的经验基础。本研究中确定的模式和因果机制将指导类似的方法来理解和预测其他景观中火灾、牲畜和气候变化的生态影响。

In the context of global climate change and increased impacts of humans on natural landscapes, increased fire occurrence is likely to be a major cause of widespread change in forested ecosystems. Although much is known about how short-term weather conditions affect the probability of fire occurrence and its intensity, much less is known about how the history of land use and the heterogeneity of the landscape affect the ways that fires spread and ecosystem responses to fire. Through a multi-scale study in northern Patagonia, Argentina, this project will address the following key questions: (1) How does landscape heterogeneity resulting from fires and other forms of disturbance over the last two centuries affect the spread of fire and subsequent post-fire vegetation and fuel changes? (2) What are the effects of climatic conditions on post-fire vegetation recovery, especially tree regeneration? (3) What are the effects of livestock and other forms of land use on the critical, early phases of post-fire vegetation and fuels recovery? These three questions will be examined by an integrated multi-scale approach to vegetation dynamics and landscape ecology across a range of ecosystem types from dry shrublands to wet forests. The researchers will integrate broad-scale spatial analyses of vegetation and fire patterns derived from historical aerial photographs and satellite images with detailed field studies of disturbance history based on tree-ring samples. These methods will be combined with experimental manipulation of moisture availability and herbivory by livestock to simulate the effects of climatic variation and land use on vegetation recovery after fire.The proposed research will advance a long-term research program initiated in 1985 focusing on the processes through which natural disturbance, climatic variability, and human activities have and continue to alter Northern Patagonian landscapes. The expected results will quantify relationships of fire behavior and effects to landscape heterogeneity at spatial and temporal scales useful for resource managers. The results will also provide a strong empirical basis for realistic application of spatial landscape-models to predicting fire behavior and fire effects in this landscape. The patterns and causal mechanisms identified in this study will guide similar approaches to understanding and predicting the ecological effects of fire, livestock, and climatic variability in other landscapes.