Soil Respiration and Microbial Diversity in a Subalpine Forest

我们将调查科罗拉多州亚高山森林生态系统中土壤微生物(真菌和细菌)高和低呼吸率(二氧化碳损失)的原因。土壤呼吸是影响生态系统碳平衡的主要过程之一，从而影响生态系统吸收化石燃料和生物质燃烧排放到大气中的二氧化碳的能力。在科罗拉多州的亚高山森林生态系统中，土壤呼吸每年将森林中光合作用树木所吸收的二氧化碳的40%-60%返回大气。这一数值很可能因长期气候变暖而从多雨年到少雨年发生显着变化。我们将通过研究释放二氧化碳的土壤微生物对时空变化的响应来寻求理解为什么它会发生如此大的变化。我们将结合现代DNA“指纹”技术来确定在任何时间点和空间点存在哪些和多少微生物，以及与这些微生物相关的土壤呼吸的大小。我们还将研究长期气候变化的模拟处理的影响，如加温灯和变化的积雪，以确定土壤呼吸速率对气候变化的响应，以及由于微生物多样性和数量的变化而导致这种响应的原因。总体而言，这项研究将使我们更好地了解土壤微生物动力学及其与土壤呼吸的关系，土壤呼吸是全球碳循环的关键组成部分之一。这项研究将通过研究助理支持培训两名研究生，他们将极大地推动探索土壤样本中微生物存在的技术的发展。后一种能力可能会被证明对国土安全部未来的努力非常有用，特别是在检测微量潜在危险微生物方面。这笔赠款还将支持圣地亚哥州立大学一名初任教员(大卫·利普森)的职业生涯。

We will investigate the causes of high versus low rates of respiration (CO2 loss) by soil microorganisms (fungi and bacteria) in a subalpine forest ecosystem in Colorado. Soil respiration is one of the dominant processes affecting ecosystem carbon balance, and thus affecting the capacity for ecosystems to absorb carbon dioxide that is emitted to the atmosphere from fossil fuel and biomass burning. In the subalpine forest ecosystem of Colorado, soil respiration is responsible for returning 40-60% of the CO2 that is absorbed by the photosynthetic trees of the forest, to the atmosphere each year. It is likely that this value changes significantly from wet to dry years and in response to long-term climate warming. We will seek to understand why it changes so much by studying changes in the soil microorganisms that release the CO2 in response to spatial and temporal variation. We will combine modern DNA "fingerprinting" techniques to determine which, and how many, microorganisms are present at any point in time and at any point in space, and the magnitude of soil respiration associated with those organisms. We will also study the influences of simulated treatments for long-term climate change in the form of warming lamps and altered snow pack to determine the response of soil respiration rate to climate change, and the causes of such responses due to changes in the diversity and amounts of microorganisms. overall, the research will provide us with an improved understanding of soil microorganism dynamics and their relationship to soil respiration, one of the critical components of the global carbon cycle.The studies will provide for the training of two graduate students through Research Assistant support, and they will significantly advance the development of techniques to probe soil samples for the presence of microorganisms. This latter capability may turn out to be very useful to future efforts in Homeland Security, especially with regard to detecting trace amounts of potentially dangerous microorganisms. The grant will also support the career of a beginning faculty member (David Lipson) at San Diego State University.