Dissertation Research: Winter soil respiration in southeast Wyoming

在季节性积雪覆盖的地区，冬季土壤中活根和微生物的新陈代谢可能是陆地生态系统每年向大气转移二氧化碳总量的重要组成部分。该项目将测量怀俄明州东南部的冬季土壤呼吸，并确定控制它的因素。已经在一系列生态系统中建立了测量小区，从短草草原到经历了广泛冬季气候条件的亚高山森林。海拔最高的地方约有10,000英尺，是一片亚高山森林，在10英尺深的地方积雪超过8个月。海拔最低的地方，海拔5400英尺，只有四个月的积雪，而且是浅的和零星的。这导致了仲冬土壤环境的反差。在高海拔地区，雪提供了一层很深的绝缘层，有效地使土壤免受极端寒冷的空气温度的影响，防止土壤结冰。相比之下，海拔最低的地方的土壤通常直接暴露在空气中，并经常在隆冬冻结。这有一个违反直觉的结果，即在最高海拔的最冷、最多雪的生态系统中，土壤在仲冬实际上是最热的。负责土壤呼吸的生物，主要是细菌、真菌和植物根，依靠液态水的存在来发挥生物活性。因此，预计海拔最高的地点在冬季的土壤呼吸速率将高于海拔最低的地点。将对不同研究地点的土壤呼吸进行测量，以确定来自微生物和根部的相对数量。将进行实验室实验，以确定在寒冷温度下对呼吸的控制。在一年多的时间里，从陆地进入大气的二氧化碳流量是燃烧化石燃料释放的二氧化碳流量的数倍。在地球上，大部分释放的碳被植物吸收。但相对释放和吸收速率的微小变化可能会对大气中的二氧化碳浓度产生重大影响。目前的计算机模型通常包含对土壤过程以及它们可能如何应对气候变化的过于简单的描述，特别是在寒冷的温度下。因此，重要的是要了解控制这些过程的相互作用的生物和物理因素。除了解决与社会相关的全球气候变化问题外，该项目还将通过雇用一名本科生研究助理来帮助教育和培训新一代科学家。

In seasonally snow covered regions, the metabolism of living roots and microorganisms in the soil over the winter may be an important part of the total annual transfer of carbon dioxide from ecosystems on land into the atmosphere. This project will measure wintertime soil respiration in southeast Wyoming and determine the factors that control it. Measurement plots have been established across a range of ecosystems from short grass prairies to subalpine forests that experience a wide range of winter weather conditions. The highest elevation site, at about 10,000 feet, is a subalpine forest that has snow cover for more than eight months at depths up to ten feet. The lowest elevation site, at 5400 feet, has only four months of snow that is shallow and patchy. This results in contrasting midwinter soil environments. At the high elevation site, snow provides a deep insulating layer that effectively insulates the soil from extremely cold air temperatures and prevents soil freezing. In contrast, soils at the lowest elevation site are often directly exposed to the air and often freeze in midwinter. This has the counterintuitive result that soils in the coldest, snowiest ecosystems at the highest elevations are actually the warmest in midwinter. The organisms responsible for soil respiration, mainly bacteria, fungi and plant roots, rely on the presence of liquid water to be biologically active. Therefore, it is expected that the highest elevation sites will have higher rates of soil respiration during the winter than the lowest elevation sites. Measurements will be made of soil respiration at the different study sites in ways that will enable the relative amounts coming from microbes and roots to be determined. Laboratory experiments will be done to determine the controls over respiration at cold temperatures. Over a year the flux of carbon dioxide from the land into the atmosphere is many times greater than the amount released by the burning of fossil fuels. Over the earth, most of the released carbon is taken back up by plants. But small shifts in the relative rates of release and uptake can have a large impact on atmospheric concentrations of carbon dioxide. Current computer models generally contain overly simple descriptions of soil processes and how they may respond to climate change, particularly at cold temperatures. Therefore, it is important to learn about the interacting biological and physical factors that control these processes. In addition to addressing the socially relevant issue of global climate change, this project will help educate and train a new generation of scientists through the employment of an undergraduate research assistant.