Doctoral Dissertation Research: Cross-Scale Assessment of Spatiotemporal Patterns and Drivers of Fire Effects in Mixed-Severity Fire Regime Forests of the Northern Rockies

博士论文研究：北落基山脉混合严重火灾区森林火灾影响的时空模式和驱动因素的跨尺度评估

• 批准号: 1302233
• 负责人: Thomas Veblen
• 金额: $ 1.6万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1302233&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Cross; Scale

This doctoral dissertation research project is about the influence of climatic variability and topographic gradients on the spatial and temporal variation of landscape patterns of fire severity from the 1700s to the present. Both fire frequency and the annual area burned are strongly related to regional climate and have exhibited increasing trends over recent decades in relation to global warming. However, the ecological effects of increased fire activity are not clearly understood. As a measure of tree mortality, fire severity directly describes one of the major ecological impacts of wildfires. But how sensitive fire severity is to climatic factors or other controls (i.e. topographic factors, vegetation characteristics) is poorly understood. Because fire severity in many forest ecosystems varies over both space and time, long time series of fire severity that quantify spatial patterns of heterogeneity are necessary, both to capture the full range of fire effects and to identify the key drivers of this variation. This is especially true for forests characterized by mixed-severity fire regimes where fire severity is known to be highly variable. This research will adopt a spatially explicit nested research design combining intensive tree-ring sampling, extensive analyses of historical high resolution aerial photography and satellite-based change detection methods to address three primary research goals: 1) to quantify the spatiotemporal variability of fire severity within multiple watersheds from about 1700-present; 2) to evaluate the strength of climatic and topographic controls on landscape patterns of fire severity; and 3) to compare fire severity patterns between historical and contemporary wildfires to assess the role of climate change on fire regime shifts between the two periods. These questions will be examined for Douglas fir (Pseudotsuga menziesii) dominated forests and mixed-conifer western larch (Larix occidentalis) dominated forests, two of the dominant low-middle elevation forests in the northern Rocky Mountains known to exhibit mixed-severity fire regimes.Information about how spatiotemporal patterns of fire severity have varied over time and which factors have driven this variability is an important framework for scientists, land managers and others interested in past and future ecological effects of wildfires. The detailed understanding of climate-fire severity relationships provided by this research is a novel and necessary foundation for accurate modeling of future fire severity and land management planning in response to currently shifting climatic conditions. Results from this research will be published in various publications and presented to academic and management audiences. Findings will also be broadly disseminated through ongoing partnerships with National Park Service (NPS) managers, U.S. Department of Agriculture (USDA) Forest Service managers and researchers, and investigators at other several universities involved in related research. The project involves the training of undergraduate and graduate students, and as a Doctoral Dissertation Research Improvement award will provide needed support to a promising doctoral student at a critical stage of career development.

这篇博士论文的研究项目是关于气候变化和地形梯度对18世纪至今火灾严重程度景观格局时空变化的影响。火灾频率和年燃烧面积与区域气候密切相关，近几十年来与全球变暖有关的趋势有所增加。然而，火灾活动增加的生态影响还不清楚。作为衡量树木死亡率的指标，火灾严重程度直接描述了野火的主要生态影响之一。但是，人们对火灾严重程度对气候因素或其他控制因素（即地形因素、植被特征）的敏感程度知之甚少。由于许多森林生态系统中的火灾严重程度在空间和时间上都有变化，因此有必要对火灾严重程度的长时间序列进行量化，以确定异质性的空间格局，以捕捉火灾的全部影响，并确定这种变化的关键驱动因素。这是特别真实的森林特点的混合严重火灾制度，火灾的严重程度是众所周知的高度可变的。本研究将采用空间显式嵌套研究设计，结合密集的树木年轮采样、历史高分辨率航空摄影的广泛分析和基于卫星的变化检测方法，以解决三个主要研究目标：1）量化1700年至今多个流域内火灾严重程度的时空变化; 2）评估气候和地形对火灾严重性景观模式的控制强度; 3）比较历史和当代野火之间的火灾严重性模式，以评估气候变化对两个时期之间火灾状况变化的作用。这些问题将被审查为道格拉斯冷杉（黄杉）占主导地位的森林和混合针叶西部落叶松（落叶松）为主的森林，两个占主导地位的低中海拔森林在北方落基山脉已知的表现出混合严重性火灾制度。有关火灾严重程度的时空模式如何随时间变化以及哪些因素驱动了这种变化的信息是科学家的一个重要框架，土地管理人员和其他对野火过去和未来的生态影响感兴趣的人。本研究提供的气候-火灾严重程度关系的详细了解是一个新的和必要的基础，为准确建模未来火灾的严重程度和土地管理规划，以应对目前不断变化的气候条件。这项研究的结果将发表在各种出版物上，并提交给学术和管理人员。调查结果还将通过与国家公园管理局（National Park Service）管理人员、美国农业部（USDA）林务局管理人员和研究人员以及参与相关研究的其他几所大学的调查人员的持续合作关系广泛传播。该项目涉及本科生和研究生的培训，作为博士论文研究改进奖，将在职业发展的关键阶段为有前途的博士生提供必要的支持。