Long-term, Intersite Experiments of Leaf and Fine Root Decomposition

叶和细根分解的长期、位点间实验

• 批准号: 9108329
• 负责人: Mark Harmon
• 金额: $ 55.02万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-07-15 至 1997-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9108329&HistoricalAwards=false
• 关键词: Long; term; Intersite; Experiments; Leaf

Decomposition can be thought of as a continuous process beginning with fresh plant litter and leading to formation of increasingly refractory organic matter. This refractory material in turn influences nutrient availability, production, and carbon sequestration in ecosystems. At present, only early stages of the decomposition process have been intensively researched. The few long-term data available indicate the decomposition process begins with an initial rapid loss of labile litter constituents and becomes progressively slower as more recalcitrant compounds compose an increasingly large fraction of the remaining material. This continuum can be divided into two phases: the first phase is characterized by a relatively rapid loss of mass, immobilization of nutrients, and a rapidly declining overall decomposition rate; the second phase is characterized by uniformly slow decomposition rates and is accompanied by nutrient mineralization. Transition between these two phases appears to occur when the lignocellulose index reaches 0.5. A team of scientists, LIDET (Long-term Intersite Decomposition Experiment Team), has started a set of experiments to test whether these general relationships are consistent across a wide range of macroclimates and substrate qualities. These long-term experiments involve 17 LTER and 4 other cooperating sites, and a total of 31 types of litter. Experiments are designed to follow changes in mass, carbon fractions, and total nitrogen and phosphorus for up to 10 years. This newly funded component of the study supports the addition of 7 new sites to represent conditions that are not yet covered. It also supports the chemical characterization of changes in litter as it decomposes and testing of four decomposition models (CENTURY, GEM, GENDEC, and VEGIE) to predict long term dynamics across the full suite of 28 sites. The analysis and modeling exercise will assess the ability of models to predict the amount of carbon, nitrogen, and phosphorus during the second phase of litter decomposition, as well as the timing of transition between the initial phase of constant mass loss and the final phase of very slow mass loss. The LIDET team of twenty-eight scientists is coordinated through the electronic mail network established under LTER to foster intersite communication. This outstanding research team is coordinated by Drs.Harmon, Melillo, Moorhead, Parton, Rastetter and Aber.

分解可以被认为是一个连续的过程，从新鲜的植物凋落物开始，导致越来越难分解的有机物的形成。 这种耐火材料反过来影响生态系统中的养分利用率、生产和碳封存。 目前，仅对分解过程的早期阶段进行了深入研究。 少数可用的长期数据表明，分解过程首先是不稳定的垃圾成分的快速损失，然后随着更多的顽固化合物在剩余材料中所占的比例越来越大，分解过程逐渐变慢。 这个连续体可以分为两个阶段：第一阶段的特点是相对较快的质量损失、营养物质的固定化和总体分解率的快速下降； 第二阶段的特点是分解速度均匀缓慢，并伴随着营养物矿化。 当木质纤维素指数达到 0.5 时，这两个阶段之间似乎会发生转变。 LIDET（长期位点间分解实验小组）的科学家团队已开始进行一系列实验，以测试这些一般关系在各种宏观气候和基质质量中是否一致。 这些长期实验涉及17个LTER和4个其他合作站点，总共31种垃圾。 实验旨在跟踪质量、碳分数以及总氮和总磷的变化长达 10 年。 这项新资助的研究部分支持添加 7 个新站点来代表尚未涵盖的情况。 它还支持垃圾分解时变化的化学特征，并测试四种分解模型（CENTURY、GEM、GENDEC 和 VEGIE），以预测 28 个地点的全套长期动态。 分析和建模练习将评估模型预测凋落物分解第二阶段期间碳、氮和磷含量的能力，以及恒定质量损失的初始阶段和非常缓慢的质量损失的最终阶段之间的过渡时间。 LIDET 团队由 28 名科学家组成，通过 LTER 下建立的电子邮件网络进行协调，以促进站点间的沟通。 这个杰出的研究团队由 Harmon、Melillo、Moorhead、Parton、Rastetter 和 Aber 博士协调。