DISSERTATION RESEARCH: Linking phenotypic variation in plant anti-herbivore defense to spatial variation in soil nutrient pools

氮等营养物质在生态系统中的循环是维持农业、城市和自然土地的生物多样性和环境服务的关键过程。 越来越多的证据表明，植物和动物物种相互作用的方式可以控制营养循环的速度。例如，许多植物通过在组织中产生防御性的抗草食动物化学物质来应对草食动物的损害，以抵御进一步的损害。这些防御性化合物还可以通过削弱微生物分解来减缓死亡植物材料进入土壤时的氮循环速率。了解土壤养分环境如何改变植物生长和植物防御的产生对于有兴趣在最大限度地提高产量的同时减少农药和肥料使用的农学家至关重要。研究结果将通过一个讲习班和研讨会传达给研究地点附近的当地利益攸关方和小规模农民，该讲习班和研讨会旨在将生态系统动态知识纳入可持续土地管理战略。此外，继续与当地乡镇保护委员会合作，将研究结果直接纳入土地管理战略。研究结果将通过在专业会议上的演讲分享，资金将支持对本科生项目的指导，并有可能共同撰写论文。将基因与生态系统功能联系起来是生态系统生态学的一个新焦点，因为植物的基因型决定了它如何发挥功能，从而有可能影响生态系统过程。然而，植物基因型也受其生长环境的影响，导致不同环境条件下的性状表达差异。了解这种性状可塑性如何与生态系统功能联系起来，对于预测环境变化如何影响氮（N）循环等生态系统过程至关重要。草食动物，结构抗草食动物防御化合物和网站的生育率之间的相互作用都可以影响性状的可塑性，从而影响基因和生态系统之间的连接。这些相互作用将检查操纵生长环境中的几个不同的基因型的一种常见的草甸植物，一枝黄花（一枝黄花），在不同的条件下，先天表达不同的抗草食动物防御笼养床花园种植。实验将排除或添加Melanoplus femurrubrum蚱蜢食草动物，并排除或添加肥料。这项研究将测量土壤微生物分解不同草食动物和肥料条件下生长的基因型植物落叶的速度。随后的实验将测量这种处理如何改变土壤微生物群落，土壤氮的可用性，以及随后的植物生长和性状。最后，15N示踪实验将允许通过跟踪土壤和植物中的氮量来测量氮循环，在氮被微生物分解后释放。总之，这些实验将确定是否植物基因型，植物抗草食动物性状的表达，或土壤氮水平最好地预测生态系统内的N循环。

The cycling of nutrients such as nitrogen through ecosystems is a critical process that maintains biodiversity and environmental services of agricultural, urban, and natural lands. There is increasing evidence that the way plant and animal species interact with each other could control the rate of nutrient cycling. For instance, many plants respond to herbivore damage by producing defensive anti-herbivore chemicals in their tissues to ward off further damage. These defensive compounds could also slow down the nitrogen cycling rate when dead plant material enters the soil by impairing microbial decomposition. Understanding how the soil nutrient environment changes plant growth and the production of plant defenses is of critical importance to agronomists interested in lowering pesticide and fertilizer use while maximizing yield. Results of the study will be communicated to local stakeholders and small-scale farmers near the study site through a workshop and seminar designed to integrate knowledge of ecosystem dynamics into sustainable land management strategies. In addition, continuing engagement with a local township conservation commission will incorporate study results directly into land management strategies. Results will be shared through presentations at professional meetings and funding will support the mentoring of undergraduates on projects with the potential for co-authorship on publications that arise from the work.Linking genes to ecosystem function is a recent focus in ecosystem ecology, because a plant's genotype determines how it functions and thus has the potential to impact ecosystem processes. Plant genotypes are also shaped by their growing environment, however, resulting in differential trait expression across environmental conditions. Knowing how such trait plasticity connects to ecosystem functioning is fundamental to prediction of how environmental change will influence ecosystem processes like nitrogen (N) cycling. Interactions among rates of herbivory, structural anti-herbivore defensive compounds, and site fertility can all affect trait plasticity and thus can affect the connections between genes and ecosystems. These interactions will be examined manipulating the growing environment in caged raised bed garden plantings of several different genotypes of a common meadow plant, goldenrod (Solidago altissima), which innately express anti-herbivore defenses differently under different conditions. The experiment will exclude or add Melanoplus femurrubrum grasshopper herbivores and exclude or add fertilizer. The study will measure how rapidly soil microbes decompose plant leaf litter from the genotypes grown in the different herbivory and fertilizer conditions. Subsequent experiments will measure how this processing changes soil microbial communities, soil nitrogen availability, and subsequent plant growth and traits. Finally, a 15N tracer experiment will allow measurement of nitrogen cycling by tracking the amount of nitrogen in the soil and in plants after it is released by microbial decomposition. Taken together these experiments will determine whether plant genotype, the expression of plant anti-herbivore traits, or soil N level best predicts N cycling within ecosystems.