Dissertation Research: Winter soil respiration in southeast Wyoming

在季节性积雪覆盖的地区，冬季土壤中的活根和微生物的代谢可能是每年从陆地生态系统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。从短草草原到亚高山森林的一系列生态系统都建立了测量区，这些生态系统经历了广泛的冬季气候条件。海拔最高的地方，大约10,000英尺，是一个亚高山森林，积雪覆盖了八个多月，深度达10英尺。海拔最低的地点位于5400英尺处，只有四个月的积雪，而且很浅且不均匀。这导致了对比鲜明的仲冬土壤环境。在高海拔地区，雪提供了一个很深的绝缘层，有效地将土壤与极冷的空气温度隔离开来，防止土壤冻结。相比之下，海拔最低的土壤往往直接暴露在空气中，往往在仲冬冻结。这有一个违反直觉的结果，即海拔最高的最冷、最多雪的生态系统中的土壤实际上在仲冬是最温暖的。负责土壤呼吸的生物，主要是细菌、真菌和植物根系，依赖于液态水的存在才具有生物活性。因此，预计海拔最高的地点在冬季的土壤呼吸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，以确定微生物和根系的相对数量。将进行实验室实验以确定在低温下对呼吸的控制。在一年的时间里，从陆地进入大气层的二氧化碳流量比燃烧化石燃料释放的量大很多倍。在地球上，大部分释放的碳被植物吸收。但是，释放和吸收的相对速率的微小变化可能对大气中二氧化碳的浓度产生巨大影响。目前的计算机模型通常包含对土壤过程的过于简单的描述，以及它们如何应对气候变化，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。 除了解决全球气候变化的社会相关问题外，该项目还将通过雇用一名本科生研究助理，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.