Vulnerability of Soil Organic Matter to Temperature Changes: Exploring Constraints Due to Substrate Decomposability and Microbial Community Structure

最近的研究表明，即使是温和的温度上升也可能导致土壤中大量的二氧化碳释放。 温度升高一度，土壤中的碳损失（以CO2计）相当于所有化石燃料燃烧每年释放的CO2的五倍。然而，这种预测是基于短期研究的结果，隐含地假设土壤中的所有碳都对温度敏感。大部分适用的研究表明，较旧的，更耐碳馏分可能比较新的，不耐碳馏分的温度敏感性低。本项目将评估保护土壤碳不被分解的物理、化学和生物化学机制在多大程度上降低土壤碳的温度敏感性。一个重要的推论是，土壤碳储量不像以前想象的那样容易受到温度变化的影响。作为该项目的一部分，我们将评估土壤中碳组分的温度敏感性，这些碳组分在不稳定碳与相对稳定碳的相对丰度方面有所不同。这项工作的结果将减少土壤碳储量对温度变化的脆弱性的不确定性，从而改善可用于帮助决策者的信息。这项研究还将推进我们对基本生态系统动态的理解，为本科生和研究生培训提供一些独特的机会，并建立国际合作。

Recent research suggests that even modest temperature increases could cause large releases of CO2 from soils. A one-degree temperature increase could prompt soil carbon losses (as CO2) equivalent to five times the annual CO2 release from all fossil fuel burning. However, such forecasts are based on results from short-term studies that implicitly assume all of the carbon in the soil is uniformly temperature-sensitive. The bulk of applicable research suggests that older, more resistant carbon fractions may be less temperature-sensitive than younger, less resistant carbon fractions. This project will evaluate the extent to which the physical, chemical, and biochemical mechanisms that protect soil carbon from decomposition act to reduce the temperature sensitivity of soil carbon. An important corollary is that soil carbon stocks are less vulnerable to changes in temperature than previously supposed. As a part of this project, we will evaluate temperature sensitivities of soil carbon fractions in soils that differ with regard to their relative abundances of labile versus relatively stable carbon. Results from this work will reduce uncertainty about the vulnerability of soil carbon stocks to changes in temperature, thus improving information available to aid decision makers. This research will also advance our understanding of basic ecosystem dynamics, present a number of unique opportunities for undergraduate and graduate training, and build international collaboration.