Development and Calibration of a New Method of Reconstructing Fire History in Low-Severity Fire Regimes

低度火灾重建火灾历史新方法的开发和校准

• 批准号: 1059159
• 负责人: William Baker
• 金额: $ 9.86万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1059159&HistoricalAwards=false
• 关键词: Development; Calibration; New; Method; Reconstructing

This research project will address a basic hypothesis in biogeography -- that the structure of dry pine forests like ponderosa pine is dominated by a low density of large trees and is maintained by frequent low-severity fires that limited tree regeneration. This hypothesis rests in part on the assumption that low-severity fires were historically frequent, an assumption largely dependent on a fire-history method that uses composite fire intervals. Some evidence has been presented from analysis, simulation, and an initial modern calibration that the use of composite fire intervals is biased and inaccurate. To overcome limitations of the composite-fire-interval method, the investigators have developed a new approach, the all-tree-fire-interval (ATFI) method, and showed by simulation that the use of is new method is unbiased and accurate. This project will complete a field-based modern calibration and apply the ATFI method in a historical fire-history reconstruction to bring the ATFI method to facilitate use of this method to help test the basic hypothesis. The investigators will first gather and analyze field data on scarring fraction, a central parameter needed for using the ATFI method, by sampling about 48 plots in 22 fires that burned in ponderosa pine forests in northern Arizona, a key area for current understanding of low-severity fire. This scarring-fraction analysis will facilitate development of a spatial model to predict scarring fraction from environmental setting, tree characteristics like density and diameter, and fuels. The scarring-fraction model then will be used to complete a modern calibration of the ATFI method and historical fire-history reconstructions using the ATFI method in 1000-ha areas in Grand Canyon National Park and Fort Valley Experimental Forest. The investigators will extract and cross-date about 640 increment cores to date trees and about 105 fire scars to count fires for the ATFI calibration and reconstruction. Finally, they will complete a spatial analysis of extant pre-EuroAmerican fire-scar evidence in these two areas to improve basic understanding of how fire-scar evidence occurs across landscapes. In the process of completing these three parts of the research, the investigators will test seven specific hypotheses about scarring fraction, three about fire history, and three about extant fire-scar evidence. They expect to be able to greatly improve understanding of how fire-scar evidence is left by fires and how to use this evidence to accurately reconstruct the history of low-severity fire across landscapes. This project will test and validate a new method for accurately reconstructing fire history in forests. Fire histories provide fundamental information needed in managing forests in national parks, national forests, and on other public lands. More specifically, this project will further develop a new fire-history method and help to resolve uncertainties about the rate that historical fires burned in ponderosa pine forests. Too much fire or too little fire can have adverse effects on old-growth trees, understory plants, and wildlife, so it is important to resolve this uncertainty. The research undertaken in this project will provide both field and laboratory educational opportunities for a graduate student and several undergraduate students.

该研究项目将解决森林地理学中的一个基本假设，即像黄松这样的干燥松树林的结构由低密度的大树主导，并由频繁的低严重程度火灾维持，限制了树木再生。 这一假设部分基于低严重性火灾在历史上频繁发生的假设，这一假设在很大程度上取决于使用复合火灾间隔的火灾历史方法。 从分析、模拟和最初的现代校准中已经提出了一些证据，表明使用复合射击间隔是有偏见的和不准确的。 为了克服复合射击间隔法的局限性，研究人员开发了一种新的方法，全树射击间隔法（ATFI），并通过模拟表明，使用这种新方法是无偏的和准确的。 本项目将完成基于现场的现代校准，并将ATFI方法应用于历史火灾历史重建中，以使ATFI方法便于使用该方法来帮助验证基本假设。 研究人员将首先收集和分析疤痕分数的现场数据，这是使用ATFI方法所需的一个中心参数，通过在北方亚利桑那州的黄松林中燃烧的22场火灾中取样约48个地块，这是目前了解低严重性火灾的关键领域。 这种疤痕分数分析将促进空间模型的发展，以预测疤痕分数的环境设置，树木的特点，如密度和直径，和燃料。 然后将使用疤痕分数模型来完成现代校准的ATFI方法和历史火灾历史重建使用ATFI方法在1000公顷的地区在大峡谷国家公园和堡谷实验森林。 调查人员将提取和交叉日期约640个增量核心日期的树木和约105个火灾疤痕计数火灾的ATFI校准和重建。 最后，他们将完成对这两个地区现存的前欧美火痕证据的空间分析，以提高对火痕证据如何在景观中发生的基本理解。 在完成这三个部分的研究过程中，研究人员将测试七个关于疤痕分数的具体假设，三个关于火灾历史的假设，以及三个关于现存的火痕证据的假设。 他们希望能够大大提高对火灾留下的火痕证据的理解，以及如何利用这些证据准确地重建整个景观中低严重性火灾的历史。该项目将测试和验证一种准确重建森林火灾历史的新方法。 火灾历史提供了管理国家公园、国家森林和其他公共土地上的森林所需的基本信息。 更具体地说，该项目将进一步开发一种新的火灾历史方法，并帮助解决有关美国黄松森林历史火灾燃烧率的不确定性。 太多的火或太少的火会对古老的树木，林下植物和野生动物产生不利影响，因此解决这种不确定性很重要。 在这个项目中进行的研究将提供现场和实验室教育的机会，为研究生和几个本科生。