Collaborative Research: MSB-ECA: Resolving controls on lignin decomposition at the continental scale to reconcile classical and modern paradigms of soil organic matter

木质素是植物组织的重要组成部分，由于其复杂的化学结构，其提供对草食动物和病原体的保护。当植物组织死亡并进入土壤时，木质素通常是最后分解的成分之一，可能持续数十年甚至更长时间。尽管木质素的衰变速度通常很慢，但最近的研究表明，许多土壤的有机质中含有很少的木质素。这一明显的矛盾对我们理解土壤有机质形成提出了一个关键挑战，这一主题与土壤肥力、水质和碳储存等环境服务密切相关。这项研究旨在了解控制木质素腐烂率的环境因素以及木质素对北美生态系统土壤有机质的最终贡献。将评估不同生态系统中土壤微生物和矿物质差异对木质素分解的影响。将使用数学模型研究这些结果对生态系统功能和服务的更广泛影响。一名博士后研究员和研究生将接受培训，研究结果将通过有针对性的外联活动传达给公众和土地管理者。这项研究旨在解决土壤有机质中挥之不去的不一致性，其中木质素的特定背景重要性可能因空间和方法采样偏差而被忽视。木质素，土壤地球化学特征和微生物群落组成之间的相互作用可能会产生显着的影响木质素停留时间和矿物吸附，出现只有当检查跨大陆尺度的环境梯度。从国家生态观测网络（氖）收集的数据将与新的实验相结合，以检验两个假设：（1）木质素分解速率及其在土壤有机质中的丰度是否可预测地随大陆尺度土壤地球化学特征和微生物群落组成而变化（与传统和现代土壤有机质范式相反）？以及（2）在一个最先进的机械生态系统模型中，木质素分解和碳循环的表示是否可以通过包括地球化学和微生物参数（除了传统的气候、残渣质量和养分可用性等变量之外）来改进？ 该氖数据将结合实地和实验室培养的碳同位素标记的木质素和核磁共振光谱测量，以测试这些hypothesis.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Lignin is an important component of plant tissues that provides protection from herbivores and pathogens due to its complex chemical structure. When plant tissues die and enter the soil, lignin is often among the last components to decompose and may persist for decades or even longer. Despite the generally slow decay rates of lignin, recent work has suggested that many soils contain very little lignin in their organic matter. This apparent contradiction presents a key challenge for our understanding of soil organic matter formation, a topic which is critically linked to environmental services including soil fertility, water quality, and carbon storage. This research seeks to understand the environmental factors that control lignin decay rates and the ultimate contributions of lignin to soil organic matter in ecosystems across North America. The influence of differences in soil microorganisms and minerals on lignin decomposition across diverse ecosystems will be assessed. The broader implications of the findings for ecosystem functions and services will be studied by using a mathematical model. A postdoctoral researcher and graduate students will be trained, and findings will be communicated to the public and to land managers with targeted outreach activities.This research seeks to resolve lingering inconsistencies in soil organic matter, where the context-specific importance of lignin may have been neglected due to spatial and methodological sampling biases. Interactions among lignin, soil geochemical characteristics, and microbial community composition may have significant impacts on lignin residence times and mineral sorption that emerge only when examined across continental-scale environmental gradients. Data collected from National Ecological Observatory Network (NEON) sites will be combined with new experiments to test two hypotheses: (1) Does lignin decomposition rates and its abundance in soil organic matter predictably vary with soil geochemical characteristics and microbial community composition at the continental scale (in contrast to both classical and modern paradigms of soil organic matter)?; and (2) Can the representations of lignin decomposition and carbon cycling in a state-of-the-art mechanistic ecosystem model be improved by inclusion of geochemical and microbial parameters (in addition to the traditional variables of climate, residue quality, and nutrient availability)? The NEON data will be combined with field and laboratory incubations of carbon isotope-labeled lignins and nuclear magnetic resonance spectroscopic measurements to test these hypotheses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.