DISSERTATION RESEARCH: Changes in ecosystem carbon sequestration over 50 years of forest development

对森林碳积累的长期观测，从森林形成开始，一直持续到森林的整个生命周期，是极其罕见的。虽然地上森林生物量是一个很大的，很容易测量的碳库，但土壤和枯木（粗木质碎屑，CWD）中的碳？所谓？慢池？？很少被研究。然而，这些缓慢的碳池在树木被移除或死亡后很长时间内储存碳。本研究调查了南卡罗来纳州棉田种植树苗后50年的碳积累，并估计了土壤和CWD中碳的缓慢循环池与整个森林中的碳相比。这项工作将估计和联系地上和地下的CWD动态，没有其他研究采取的步骤。虽然CWD在这片森林中积累，但深层土壤似乎自森林建立以来就失去了碳，这与重新造林应该增加或对土壤有机碳（SOC）储存没有影响的假设相反。本研究将通过详细分析森林发展过程中SOC化学和稳定性的变化，研究重新造林对土壤碳的影响。扩大研究是必要的，以了解SOC的变化是永久性的还是短暂的现象，以及什么后果将森林固碳的努力。最后，目前的碳核算协议在数据要求和对不确定性的处理方面存在差异，这导致对可信碳储量的估计存在分歧。这项对管理森林中碳储存和动态的持续研究，以及与国际长期土壤实验网络，美国林务局和尼古拉斯环境政策解决方案研究所的同事合作，将有助于制定严格的碳抵消协议，并改善土地所有者和管理者对碳储量和不确定性的估计。

Long-term observations of forest carbon accumulation, beginning at forest inception and continuing through the life of the forest, are exceedingly rare. While aboveground forest biomass is a large and easily-measured pool of carbon, carbon in soils and in dead wood (coarse woody detritus, CWD) ?so called ?slow pools??are little studied. Yet these slow pools store carbon long after trees are removed or die. This research investigates 50 years of carbon accumulation following the planting of tree seedlings in a South Carolina cotton field, and estimates the slowly cycling pools of carbon in soil and CWD in comparison to the carbon in the total forest. This work will estimate and link aboveground and belowground CWD dynamics, a step no other study has taken. While CWD has accumulated in this forest, deep soils appear to have lost carbon since forest inception, counter to assumptions that reforestation should increase or have no effect on soil organic carbon (SOC) storage. This research will examine effects of reforestation on soil carbon via detailed analyses of changes in SOC chemistry and stability during forest development. Expanded research is necessary to understand whether SOC changes are permanent or transient phenomena, and what the ramifications will be for forest carbon sequestration efforts. Finally, current carbon accounting protocols differ in data requirements and treatment of uncertainty, which results in divergent estimates of creditable carbon storage. This continued research on carbon storage and dynamics in a managed forest, and collaboration with colleagues in the international Long Term Soil Experiment network, US Forest Service, and the Nicholas Institute for Environmental Policy Solutions, will aid development of rigorous carbon offset protocols and improve estimation of carbon stocks and uncertainties by land owners and managers.