Collaborative Research: Characterizing climate-induced qualitative changes in plant biopolymer composition and their influence on soil processes

生态系统的生产力依赖于分解过程中养分的循环利用。分解主要由气候和植物凋落物的化学成分决定。传统上，腐解率是根据凋落物中碳、氮和木质素的浓度来估计的。然而，许多难以降解的化合物(生物聚合物)的结构特征，包括木质素、单宁和角质基质，可以决定整体的分解速度。植物生长的气候会强烈影响这些化合物的结构特性。因此，气候变化有可能通过改变温度和湿度直接改变分解，也可能通过改变植物凋落物中生物聚合物的结构属性间接改变分解，而这种改变没有被纳入传统的营养循环模型。这个项目有三个长期目标。第一个目标是了解生长季节、温度和水分供应如何影响生物聚合物的多样性和化学性质，这些聚合物控制着植物凋落物的分解。第二个目标是了解环境条件如何与凋落物的化学成分相互作用，从而影响分解和养分循环。第三个目标是开发和测试分解模型，将气候和生物聚合物特性的作用纳入新的知识。研究人员将使用波士顿地区气候实验中的六种植物来验证这些假设，该实验将一片片种植树苗的老田野暴露在12种可能的未来气候中。该项目的结果将改善对气候变化中碳和氮循环的预测。由于单宁与食品质量(作为抗氧化剂)、饲料质量和草食(作为威慑剂)有关，因此研究结果将应用于土壤养分动力学以外的领域。该项目将为本科生提供创造性探究的机会和一门新的课程，并将为在职K-12教师和非正规教育工作者开发一个暑期课程。该项目还将通过南卡罗来纳生活计划为该州的高中生和少数族裔大学的学生提供学习和研究经验。

The productivity of an ecosystem depends on the recycling of nutrients through the process of decomposition. Decomposition is primarily governed by climate and the chemical composition of plant litter. Traditionally, decomposition rates have been estimated using concentrations of carbon, nitrogen and lignin in the litter. However, the structural characteristics of many hard-to-degrade compounds (biopolymers), including lignins, tannins and cuticular matrices, can dictate overall decomposition rates. The climate in which plants grow can strongly influence the structural properties of these compounds. Climate change thus has the potential to alter decomposition both directly, by changing temperature and moisture, and also indirectly, by changing the structural attributes of biopolymers in plant litter, in ways that are not factored into traditional nutrient cycling models. This project has three long-term goals. The first goal is to learn how growing season temperature and moisture availability affect the diversity and chemical properties of biopolymers that govern decomposition of plant litter. The second goal is to understand how environmental conditions interact with the chemical composition of litter to affect decomposition and nutrient cycling. The third goal is to develop and test models of decomposition that incorporate new knowledge of the roles of climate and biopolymer properties. The investigators will test these hypotheses using six plant species from the Boston-Area Climate Experiment, which exposes patches of old fields with tree seedlings to twelve possible future climates. Results from this project will improve predictions of carbon and nitrogen cycling in a changing climate. The results will have application beyond soil nutrient dynamics, as tannins are relevant to food quality (as antioxidants), fodder quality and herbivory (as deterrents). The project will provide undergraduates with opportunities for creative inquiry and a new course offering, and will develop a summer course for in-service K-12 teachers and non-formal educators. The project also will provide learning and research experiences to high school students and students from the minority college in the state through the South Carolina Life program.