Collaborative Research:Impacts of Vegetation Change on Stabilization and Microbial Accessibility of Soil Organic Matter: A Microbiological, Isotopic, and Molecular Study

合作研究：植被变化对土壤有机质稳定性和微生物可及性的影响：微生物学、同位素和分子研究

• 批准号: 0525346
• 负责人: Timothy Filley
• 金额: --
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0525346&HistoricalAwards=false
• 关键词: Collaborative; Research; Impacts; Vegetation; Change

Filly0525346Soil organic matter (SOM) represents the largest pool of actively cycling organic carbon (C) and nitrogen (N) in the terrestrial environment. However, an incomplete understanding of the complex interactions that exist between plants, soils, and microbes limits our ability to quantitatively account for the storage and dynamics of these elements in global budgets. Quantifying changes to SOM within the context of land cover/land use changes will help understand better the effects of human-induced perturbations and natural variability on ecosystem shifts and climate change. An ecosystem scenario that is important for documenting modern carbon budgets as well as paleoenvironmental interpretation is woody plant/grassland transitions as approximately 45 to 52% of the terrestrial surface is covered with grasslands, savannas, shrublands, and semiarid woodlands and these grass-dominated ecosystems store 30% of global soil organic carbon (SOC). This proposal seeks to document and quantify how various biological, chemical, and physical processes act as protective mechanisms for SOC following a major vegetation change from grassland to woodland. Specifically, a chronosequence (120 yrs) of woody plant invasion into a subtropical grassland will be utilized as a model system to investigate the storage or release (as respired CO2) of organic matter from specific soil physical and chemical fractions. The overall project goal is to relate microbial community structure and enzymatic activity, plant input chemistry, and soil microfabric to the specific chemical forms of organic C and N that are stabilized and released through the chronosequence. Four questions drive the research in this proposal: 1) How does soil physical structure determine the extent of C accrual over time following woody plant invasion? 2) What is the chemical composition and source of the plant and microbial carbon that is stabilized? 3) What is the role of shifting populations of soil microbes and enzyme activity in the respiration of litter and SOM fractions and how do they impact aggregation dynamics? 4) What is the relative accessibility of the "new" SOM derived from woody plants to microbial decay, and can we relate physically identifiable SOM fractions with calculated mean residence time to potential respiration in inoculation experiments? These questions will be answered through application of novel molecular, isotopic, and microbiological methods to develop a fundamental understanding of the processes that control soil carbon storage and dynamics. The intellectual merit of this proposal rests on the potential for uncovering some of the most fundamental chemical and physical mechanisms that control one of the largest and most dynamic components of the global carbon cycle, Additionally, this work will contribute to the develop of a stronger scientific basis for modeling SOM dynamics, ecosystem processes, and the global carbon cycle. The multidisciplinary composition of the research team (ecology, biogeochemistry, microbiology) will contribute to the development of broad-based perspectives that will benefit a wide cross-section of the scientific community. The broader impacts of this work include the enhanced understanding of the role of soil processes in biogeochemical cycles and the earth system which will be of immediate significance to both scientists and policy-makers as mankind considers the potential for manipulating the carbon cycle in order to mitigate potential global climate change. Additionally, the project will generate educational opportunities for two Ph.D. students, with great promise to attract underrepresented students through Purdue's NSF Funded Alliance for Graduate Education and the Professoriate (AGEP) program. These students will receive training in state-of-the-art methodologies in biogeochemistry and global change research.

Filly0525346Siil有机物（SOM）代表了陆地环境中最大的积极循环有机碳（C）和氮（N）的池。 但是，对植物，土壤和微生物之间存在的复杂相互作用的不完全理解限制了我们定量考虑这些元素在全球预算中的存储和动态的能力。在土地覆盖/土地使用变化的背景下量化SOM的变化将有助于更好地了解人类引起的扰动和自然变异性对生态系统变化和气候变化的影响。生态系统方案对于记录现代碳预算以及古环境的解释很重要，木本植物/草地过渡是陆地表面的大约45％至52％，上面覆盖着草原，稀树草原，萨凡纳人，shrublands，shrublands和semariarid Woodlands和Semariarid Woodlands and semmand Prass-progn-proversmined的生态系统存储30％的全球土壤有机碳（SOC）。 该提案旨在记录和量化各种生物，化学和物理过程如何充当SOC的保护机制，这是从草地到林地的主要植被变化之后的。具体而言，将使用特定土壤物理和化学分数的木质植物侵入木质植物侵袭到亚热带草地的木质植物入侵有机系统。 总体项目目标是将微生物群落结构和酶活性，植物输入化学和土壤微结构与特定化学形式的有机c和n的特定化学形式联系起来，这些形式的有机c和n是通过Chronosequence稳定并释放的。 四个问题推动了该提案中的研究：1）土壤物理结构如何确定木本植物入侵后随着时间的推移c应计的程度？ 2）稳定的植物和微生物碳的化学成分和来源是什么？ 3）在垃圾和SOM馏分的呼吸中转移种群和酶活性的作用是什么？它们如何影响聚集动力学？ 4）从木质植物到微生物衰减的“新” SOM的相对可及性是什么，我们可以将物理上可识别的SOM馏分与计算出的平均停留时间与接种实验中的潜在呼吸联系起来吗？ 这些问题将通过应用新颖的分子，同位素和微生物方法来回答，以对控制土壤碳储存和动力学的过程有基本的了解。该提案的智力优点取决于揭示某些控制全球碳循环中最大，最动态的成分之一的最基本化学和物理机制，此外，这项工作将有助于发展更强大的科学。建模SOM动力学，生态系统过程和全球碳循环的基础。 研究团队的多学科组成（生态学，生物地球化学，微生物学）将有助于发展基于广泛的观点，这些观点将使科学界的广泛横截面受益。这项工作的更广泛的影响包括对土壤过程在生物地球化学周期和地球系统中的作用的增强理解，这对科学家和政策制定者都具有直接的意义，因为人类考虑了操纵碳循环的潜力，以减轻碳循环潜在的全球气候变化。此外，该项目将为两位博士带来教育机会。学生们非常有前途，可以通过普渡大学的NSF资助的研究生教育联盟和教授（AGEP）计划吸引人数不足的学生。 这些学生将接受对生物地球化学和全球变化研究的最先进方法的培训。