Sources of soil organic matter transported by soil erosion in fire-prone upland ecosystems of the Sierra Nevada

内华达山脉易发火灾的高地生态系统中土壤侵蚀输送的土壤有机质来源

• 批准号: 1147977
• 负责人: Asmeret Asefaw Berhe
• 金额: $ 7.5万
• 依托单位: University of California - Merced
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1147977&HistoricalAwards=false
• 关键词: Sources; soil; organic; matter; transported

Lateral redistribution of soil organic matter (OM) by erosion controls soil carbon stocks, stability, and mechanisms of stabilization in both natural and anthropogenically disturbed ecosystems. Little is known about the interactive effects of erosion and fire on dynamics of soil OM. Yet it is critical to understand how the coupled processes of fire and erosion affect stability and stabilization mechanisms of soil OM in fire-prone ecosystems because stability and stabilization mechanisms of soil OM (including the association of OM with soil minerals physically through aggregation and chemically through complexation of organic functional groups with metal oxides) determine 1) amount of soil OM that is combusted during fires, 2) proportion of soil OM that is redistributed and mineralized during erosional transport of sediments downhill, and 3) stability of eroded and deposited soil OM. In this project, we aim to determine the effect of watershed size and source of eroded OM on soil OM dynamics primarily in the Kings River Experimental Watershed in California. It is critical to develop an understanding of the pedologic, hydrologic, climatic, and geomorphic factors that control variability in source of eroded organic matter (OM), as these factors can influence concentration and composition of OM mobilized by soil erosion, and its enrichment in eroded sediments. This, in turn, has significant implications for determining whether erosion renders fire-affected ecosystems sources or sinks for atmospheric carbon dioxide. In addition to tackling these questions, data collected as part of this study will serve as benchmark for studying the effect of prescribed forest fires on soil OM dynamics over short and long timescales.

侵蚀引起的土壤有机质横向再分配控制着自然和人为干扰生态系统的土壤碳储量、稳定性和稳定机制。关于侵蚀和火灾对土壤有机质动态变化的交互作用，人们知之甚少。然而，了解火灾和侵蚀的耦合过程如何影响易火生态系统中土壤有机质的稳定和稳定机制是至关重要的，因为土壤有机质的稳定和稳定机制(包括通过有机官能团与金属氧化物的络合作用在物理上和化学上与土壤矿物结合)决定了1)火灾期间焚烧的土壤有机质数量，2)土壤有机质在侵蚀运移过程中重新分布和矿化的比例，以及3)侵蚀和沉积土壤有机质的稳定性。在这个项目中，我们的目标是确定流域大小和侵蚀有机质来源对土壤有机质动态的影响，主要是在加利福尼亚州的国王河实验流域。了解控制侵蚀有机质(OM)来源变异性的土壤、水文、气候和地貌因素是至关重要的，因为这些因素会影响土壤侵蚀活化的OM的浓度和组成，以及它在侵蚀沉积物中的富集。这反过来又对确定侵蚀是否使受火灾影响的生态系统成为大气二氧化碳的源或汇具有重大影响。除了解决这些问题外，作为这项研究的一部分，收集的数据将作为基准，研究规定的森林火灾对土壤有机质动态在短期和长期的影响。