Reconciling predictions of kinetic theory with observations of decomposition responses to temperature: Biochemical, biological, and edaphic constraints

由于土壤是一个巨大的碳库，温度对土壤碳动态的影响对全球碳循环和气候变化具有重要的意义。土壤有机质是由多种物质组成的，它们的分解能力各不相同。这些不同成分的分解受温度影响的程度是决定土壤在未来气候下是大气二氧化碳的汇还是源的关键因素。在领先的气候-碳模型中，这个问题没有得到解决，掩盖了一个潜在的巨大不确定性来源。这对土壤碳储量的变化有重大影响。利用通过模型开发整合的互补性实验室、田间和跨地点实验的组合，这些研究人员将检查生化和生物过程对温度的响应，特别是对酶生产的限制。他们还将明确研究土壤矿物质基质的单独影响。假设和实验方法直接与土壤有机质分解发生的机制相一致：有机质变得可供分解者使用(解吸)，并受到土壤微生物的攻击(酶作用)。因此，这个项目将产生新的知识，将基本动力学理论应用于现实世界中的分解。该项目的更广泛影响包括在两个国家全球变化会议上举办专题讨论会。本科生将参加夏季生态研究项目，从而获得宝贵的研究经验。主要研究人员将帮助两名研究生发展科学领导技能，这样研究生最终将指导本科生的研究。

Because the soil is such a large storehouse of carbon, the effects of temperature on soil carbon dynamics have important implications for the global carbon cycle and climate change. Soil organic matter is composed of a variety of materials that differ in their decomposability. The extent to which decomposition of these various components is influenced by temperature is a critical factor that determines whether soils will act as a sink or source for atmospheric CO2 under the climate of the future. This question is unaddressed in leading climate-carbon models, masking a potentially large source of uncertainty. This has substantial implications for changes in soil carbon stocks. Using a combination of complementary laboratory, field, and cross-site experiments integrated through model development, these researchers will examine the responses of biochemical and biological processes to temperature, especially constraints on enzyme production. They will also explicitly investigate the effects of the soil's mineral matrix alone. The hypotheses and experimental approach are directly aligned with the mechanisms by which soil organic matter decomposition occurs: organic matter becomes available for decomposers (desorption) and it is attacked by soil microorganisms (enzymatically). Thus, this project will generate new knowledge that applies fundamental kinetic theory to decomposition in real-world situations. The broader impacts of this project include development of symposia at two national global-change meetings. Undergraduate students will participate in the Summer Ecology Research program, thus gaining valuable research experience. The principal investigators will assist two graduate students in developing scientific leadership skills, such that the graduate students will eventually mentor undergraduates in their research.