Collaborative Research: Alterations of Soil Physical and Geochemical Properties Induced by Low-intensity Fire

合作研究：低强度火灾引起的土壤物理和地球化学性质的改变

• 批准号: 1324919
• 负责人: Teamrat Ghezzehei
• 金额: $ 22.28万
• 依托单位: University of California - Merced
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1324919&HistoricalAwards=false
• 关键词: Collaborative; Research; Alterations; Soil; Physical

The majority of fire research to date has focused on the negative impacts of large, medium-to-high intensity burns, which typically cause massive combustion of litter and organic matter in the topsoil followed by increases in soil erosion, runoff, and loss of nutrients. The positive role of fires in vegetation succession and nutrient cycling also is well recognized. In contrast, low-intensity burns (with soil temp. of 220 degrees C) are presumed to cause minimal soil degradation and landscape/ecosystem alteration. As a result, there has been only limited research investigating potential negative consequences of such burns, although they account for almost half of total burned areas in the United States. Furthermore, climate change is expected to increase the frequency and area of land exposed to such low-intensity burns. Recent long-term studies on the effect of low-intensity fires on soil structure, however, are revealing that substantial loss of soil aggregate stability and porosity occurs several months to a few years after the burn has occurred. These degradations in soil structure often are followed by reduced infiltrability and increased soil erosion. The overarching goal of this proposed research is to investigate the impacts of low-intensity fires on soil structure and the implication for soil hydrology, erosion, and nutrient dynamics. Specifically, this project is designed to test three hypotheses: a) soil structure deterioration is caused by micro-scale stresses created within aggregates due to rapid vaporization or thermal expansion of soil particles as well as preferential volatilization of mostly hydrophilic simple organic molecules; b) disaggregation and subsequent surface sealing result in reduced infiltration and increased erosion; and c) preferential mobility of nutrient-rich dislodged fine aggregates and particles results in accelerated loss of nutrients and carbon via lateral and vertical transport. The proposed research will be conducted using soil samples collected from arid and semi-arid ecosystems in eastern Nevada and will mimic characteristics of past low-intensity burns of the region.Improved understanding of how low-intensity fires can lead to land/ecosystem degradation will benefit society by enabling more effective design of controlled burns as well as post-burn land management practices. This knowledge also can play an important role in planning for mitigation of the effects of low-intensity fires in sensitive ecosystems and landscapes of arid/semi-arid regions that are expected to experience more fires as a result of climate change. This research will expand on-going collaboration with the Bureau of Land Management, thereby facilitating adoption of new advances to support science-based resource management. In addition, this project will provide educational and advanced research training to one Ph.D.-level student and one postdoctoral researcher. ?Science boxes? will be employed to engage K-12 students in results of the proposed project.

迄今为止，大多数火灾研究都集中在大，中到高强度燃烧的负面影响上，这通常会导致表土中的凋落物和有机物大量燃烧，然后增加土壤侵蚀，径流和养分流失。火灾在植被演替和养分循环中的积极作用也得到了充分的承认。相比之下，低强度烧伤（土壤温度。220摄氏度），据推测，造成最小的土壤退化和景观/生态系统的改变。因此，只有有限的研究调查这种烧伤的潜在负面后果，尽管它们占美国烧伤面积的近一半。此外，气候变化预计将增加遭受这种低强度烧伤的土地的频率和面积。然而，最近关于低强度火灾对土壤结构影响的长期研究表明，在火灾发生后几个月至几年，土壤团聚体稳定性和孔隙度会发生重大损失。土壤结构的这些退化通常会导致渗透性降低和土壤侵蚀加剧。这项研究的总体目标是调查低强度火灾对土壤结构的影响以及对土壤水文，侵蚀和养分动态的影响。具体而言，该项目旨在检验三个假设：a）土壤结构恶化是由于土壤颗粒迅速蒸发或热膨胀以及大多数亲水性简单有机分子优先挥发而在团聚体内产生的微尺度应力造成的; B）解团聚和随后的表面封闭导致渗透减少和侵蚀增加;和c）富含营养物的脱落的细聚集体和颗粒的优先移动性导致营养物和碳通过横向和垂直运输的加速损失。拟议中的研究将使用从内华达州东部干旱和半干旱生态系统采集的土壤样本进行，并将模拟该地区过去低强度火灾的特征，更好地了解低强度火灾如何导致土地/生态系统退化，将有利于社会，使更有效的控制燃烧设计以及燃烧后的土地管理实践。这方面的知识还可以在规划减轻干旱/半干旱地区敏感生态系统和景观中低强度火灾的影响方面发挥重要作用，因为这些地区预计将因气候变化而遭受更多的火灾。这项研究将扩大与土地管理局的持续合作，从而促进采用新的进展，以支持以科学为基础的资源管理。此外，该项目还将为一名博士提供教育和高级研究培训。一级研究员和一名博士后研究员。?科学盒子？将聘请K-12学生参与拟议项目的结果。