DISSERTATION RESEARCH: Carbon and Nitrogen Dynamics of Southern Great Plains Mixed Grasslands: Impacts of Seasonal Fire and Simulated Herbivory

这项研究将评估草原生态系统中植物生产力、火和草食引起的生物量转移以及元素循环之间的反馈的重要性。这些过程之间相互作用的概念模型将在大平原南部的混合草原上进行评估。这些模型的区别在于它们对植物组织质量和土壤氮素矿化速率之间的反馈的相对重要性。强调反馈的模型在特定反馈机制的性质(积极或消极)上有所不同。模型假设反馈的重要性最小，确定不同的因素(气候与C和N循环的脱钩)是肥力和植物生产力的主要调节因素。这些研究人员收集的现有数据表明，火和草食对土壤中植物输入的调节限制了这些草原上的微生物碳库，从而最大限度地减少了对C和N循环的反馈。调查人员请求支持对现有植物和土壤样本的分析，以评估土壤池中碳和氮循环之间的脱钩程度。

The research proposed here will assess the importance of feedbacks between plant productivity, biomass removal due to fire and herbivory, and element cycling in grassland ecosystems. Conceptual models of interactions among these processes will be evaluated in mixed grasslands of the southern Great Plains. These models are distinguished by the relative importance they assign to feedbacks between plant tissue quality and soil nitrogen mineralization rates. Models emphasizing feedbacks differ in the nature (positive or negative) of specific feedback mechanisms. Models assume minimal importance to feedbacks identify different factors (climate vs. decoupling of C and N cycles) as primary regulators of fertility and plant productivity. Existing data collected by these researchers suggest that that modulation of plant inputs to soils by fire and herbivory limit microbial C pools in these grasslands, thereby minimizing feedbacks to C and N cycling. The investigators request support for analysis of existing plant and soil samples to assess the degree of decoupling between C and N cycling in soil pools.