LTER Cross-site: Collaborative Research: DIRT: A Cross-continental, Experimental Study of Forest Soil Organic Matter and Nitrogen Dynamics

LTER 跨站点：合作研究：DIRT：森林土壤有机质和氮动态的跨大陆实验研究

• 批准号: 0087010
• 负责人: Richard Bowden
• 金额: $ 6.6万
• 依托单位: Allegheny College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-10-01 至 2003-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0087010&HistoricalAwards=false
• 关键词: LTER; Cross; site; Collaborative; Research

0087010BowdenNumerous studies of decomposition have focused on short-term, transient effects of organic matter breakdown. Much has been learned from these studies about the roles of litter nutrient content and carbon quality in controlling the cycling of nutrients through the litter layer to soil organic matter (SOM). However, far less is known about the fate of plant litter and its role in determining SOM content and nutrient cycling over time scales ranging from decades to centuries. To address this gap, long-term experimental studies of controls on soil organic matter formation, or DIRT (Detritus Input and Removal Treatments), have been established independently at forested sites in three US LTERs and one international LTER site. DIRT plot treatments consist of long-term above- and below ground litter doubling and removal. While the fundamental experimental design of these installations is similar, there are few measurements in common and each site is instrumented quite differently. The purpose of this LTER cross-site research project is to bring these four sites into a general experimental and measurement uniformity, and to test models and hypotheses made at individual sites over this network. The LTER program serves as an ideal host for the emerging cross-site DIRT network both because it serves as a focal point for many investigators and because of its focus on long-term studies. The central goal of the DIRT project is to assess how rates and sources of plant litter inputs control accumulation and dynamics of organic matter and nutrients in forest soils over decadal time scales. This cross-site comparison will address three specific goals: (1) to examine effects of forest floor biomass, organic matter inputs, sources, and chemistry on net N retention and the ratio of inorganic to organic N losses in leachate; (2) to examine the effects of forest floor chemistry on gross N mineralization, immobilization, and nitrification rates; and (3) to evaluate the generality of models of sources of C to soil respiration.

0087010Bowden 许多分解研究都集中在有机物分解的短期、瞬态效应上。从这些研究中，我们了解到凋落物养分含量和碳质量在控制养分通过凋落物层到土壤有机质 (SOM) 循环中的作用。然而，人们对植物凋落物的命运及其在数十年至数百年时间尺度内决定 SOM 含量和养分循环中的作用知之甚少。为了弥补这一差距，在美国三个 LTER 站点和一个国际 LTER 站点的森林地区独立开展了对土壤有机质形成或 DIRT（碎屑输入和清除处理）控制的长期实验研究。污垢地块处理包括长期地上和地下枯枝落叶的加倍和清除。虽然这些装置的基本实验设计相似，但几乎没有共同的测量结果，而且每个站点的仪器也完全不同。该 LTER 跨站点研究项目的目的是将这四个站点纳入一般实验和测量一致性，并测试通过该网络在各个站点所做的模型和假设。 LTER 计划是新兴跨站点 DIRT 网络的理想宿主，因为它是许多研究人员的焦点，也因为它专注于长期研究。 DIRT 项目的中心目标是评估植物凋落物输入的速率和来源如何控制十年时间尺度内森林土壤中有机质和养分的积累和动态。这种跨地点比较将实现三个具体目标：（1）检查森林地面生物量、有机物质输入、来源和化学对净氮保留以及渗滤液中无机氮与有机氮损失的比率的影响； (2) 检查森林地表化学对总氮矿化、固定和硝化速率的影响； (3) 评估碳源模型对土壤呼吸的通用性。