Exploring the black box: coupling above- and belowground plant traits to understand disturbance effects on soil carbon storage in a temperature plantation

政府间气候变化专门委员会最近的科学会议清楚地强调，需要基础科学来支持理解生态系统对气候变化的反馈以及随后在未来几十年作出的重要决策。这项基础科学计划的一个关键要素涉及了解碳和氮的生物地球化学循环，以及土地利用和植被反应的变化如何改变这些循环。目前的建议延续了20年来关于温带种植园生态系统养分循环的基础研究，重点是植被变化对这些循环的反馈，以及由此产生的土壤中碳的形态和相对稳定性。本五年计划将结合植物功能性状的方法，以解释集约化营林创造的不同植物群落对养分循环的影响，特别是土壤中碳的积累和稳定性。具体目标包括：1)确定主要树种(比叶面积、叶C和N)的植物特征(绿叶和凋落物)随年龄的变化；2)描述优势树种和林下物种的地上和地下特征(根)，以解释腐殖质和矿质土壤中土壤碳积累和稳定性的差异；3)进一步调查与人工林建设和土壤强烈扰动相关的更深矿层的潜在土壤碳损失(潜在引发效应)。新获得的中红外和近红外光谱方法将被应用于研究它们比现有技术更有效地评估植物组织化学和土壤碳稳定性的潜力。未来五年的长期计划将同时探索工厂对碳封存的反馈的更深层次问题，同时合成将在同一地点进行的25年(2011年)研究计划。为了完成这个项目，我将与以前的合作者和学生一起写一篇主要的合成论文。这些研究对于理解和管理森林土壤碳积累具有重要意义，也将有助于改进目前预测生态系统碳动态的模型。

The recent IPCC science meetings clearly underline the need for fundamental science to support understanding of ecosystem feedback to climate change and consequent important policy decisions in the next decades. A key element of this fundamental science program relates to understanding biogeochemical cycles of carbon and nitrogen, as well as how changes in land use and vegetation response may modify these cycles. The current proposal continues 20 years of fundamental research on nutrient cycles in temperate plantation ecosystems, with an emphasis on feedbacks of vegetation changes to these cycles, and the resulting forms and relative stability of carbon in the soil. The present five-year program will integrate the approach of functional plant traits in order to interpret the effects of different plant communities created by intensive silviculture on nutrient cycling and specifically, carbon accumulation and stability in the soil. Specific objectives include: 1) characterize age-related change in plant traits (both green foliage and litter) of dominant tree species (specific leaf area, foliar C and N) ; 2) characterize above- and belowground traits (roots) of dominant tree and understory species to interpret differences in soil carbon accumulation and stability in humus and mineral soil ; 3) further investigate potential soil carbon losses (potential priming effect) in deeper mineral horizons associated with plantation establishment and intensive soil disturbance. Newly accessible methods of mid- and near infrared spectroscopy will be applied to investigate their potential to evaluate both plant tissue chemistry and soil carbon stability more efficiently than current techniques. These next five years of a long term program will simultaneously probe deeper questions of plant feedback on carbon sequestration while synthesizing what will be a 25-year program (in 2011) of research on the same site. To culminate this program I will write a major synthesis paper with previous collaborators and students. These studies are important in order to understand and manage soil carbon accrual in forests, and will also contribute important information to improve current models for predicting carbon dynamics in ecosystems.