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

分解可以被认为是一个连续的过程， 新鲜的植物凋落物，导致越来越多的 难降解有机物 这种耐火材料反过来 影响养分的有效性、生产和碳 生态系统中的隔离。 目前，只有早期阶段的 分解过程进行了深入研究。 为数不多 长期的数据表明分解过程开始于 随着不稳定的凋落物成分的初始快速损失， 随着越来越多的柠檬酸化合物组成 越来越多的剩余材料。 这 连续体可以分为两个阶段：第一阶段是 其特征在于相对快速的质量损失、固定 营养物质的减少，以及整体分解率的迅速下降; 第二阶段的特征在于均匀缓慢的分解 并伴随着养分矿化。 过渡 这两个阶段之间似乎发生时，木质纤维素 指数达到0.5。 一个科学家团队，LIDET（长期 Intersite Decomposition Experiment Team），已经开始了一系列 实验来测试这些一般关系是否 在大范围的大气候和基质中保持一致 的天性. 这些长期实验涉及17个LTER和4个其他 合作网站，共31种垃圾。 实验 设计用于跟踪质量、碳分数和总 氮和磷长达10年。 新资助的 研究的组成部分支持增加7个新的网站， 代表尚未涵盖的条件。 它还支持 凋落物分解过程中变化的化学特征 四个分解模型（世纪，GEM，GENDEC， VEGIE），以预测28个 网站. 分析和建模练习将评估 预测碳、氮、磷含量的模型 在凋落物分解的第二阶段，以及 恒质量初始相之间的过渡时间 最后阶段是缓慢的质量损失。LIDET团队 28名科学家通过电子邮件进行协调， 在LTER下建立网络，以促进站点间通信。 这个杰出的研究团队由哈蒙博士协调， 梅里洛，穆尔黑德，帕顿，拉斯特特和阿伯。

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.