Collaborative Research: The Role of Snow Patches on the Spatial Distribution of Soil Microbial Communities and Biogeochemical Cycling in the Antarctic Dry Valleys

摘要本奖项由2009年美国复苏与再投资法案（公法111-5）资助。已经提出了两个模型来描述对微生物生物地理学的控制。一种模型提出，微生物在全球环境中无处不在，环境条件选择了在生理上适应当地物理条件的分类群。另一种模型预测，扩散是微生物分布的重要限制因素，微生物群落的空间异质性是扩散和局部环境限制的结果。根据这两种模型，微生物群落的空间异质性可能在极端生态系统中尤为明显，因为在极端生态系统中，具有适宜生理条件的生物的环境选择最为明显。我们认为南极陆地环境是研究微生物生物地理学的理想场所，原因有3:1)南极洲的原始自然和偏远使外来物种通过人类媒介传播的流行最小化；(2)南极的极端环境条件为非本土分类群的建立提供了强大的环境过滤器；3)陆地环境的极端异质性提供了土壤条件（温度、水分和养分有效性）的自然梯度。在本研究中，我们将研究积雪对麦克默多干谷土壤微生物群落组成和空间分布以及相关生物地球化学循环的影响。我们将在景观尺度（重复遥感表征积雪分布）、山谷和斑块尺度（量化山地土壤中积雪消融、微生物群落和生物地球化学循环）进行实地调查。我们假设，由于积雪对土壤环境的物理和水文影响，积雪在构建土壤微生物群落的空间分布及其相关的生态系统功能中起着重要作用。这项研究将有助于提高公众对极地研究对生物学、生态学和水文学基本问题的重要性的认识，办法是同国际南极研究所的公共宣传活动直接联系，包括传播关于环境科学和微生物学的网络学习单位，作为中等和中等以上教育工作者的资源。3名研究生、1名博士后和多名本科生参加研究活动。

AbstractThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Two models have been proposed to describe controls over microbial biogeography. One model proposes that microbes are ubiquitously distributed across the global environment, and that environmental conditions select for taxa physiologically adapted to local physical conditions. An alternative model predicts that dispersal is the important limitation to the distribution of microorganisms and that spatial heterogeneity of microbial communities is a result of both dispersal and local environmental limitations. According to both models, spatial heterogeneity of microbial communities may be especially pronounced in extreme ecosystems where the environmental selection for organisms with suitable physiology is most strongly manifest. We propose that Antarctic terrestrial environments are ideal places to examine microbial biogeography for 3 reasons: 1) the pristine nature and remoteness of Antarctica minimizes the prevalence of exotic species dispersed through human vectors; 2) the extreme conditions of Antarctic environments provide a strong environmental filter which limits the establishment of non-indigenous taxa; and 3) extreme heterogeneity in the terrestrial environment provides natural gradients of soil conditions (temperature, water and nutrient availability). In the proposed research we will investigate the influence of snow on the composition and spatial distribution of soil microbial communities and linked biogeochemical cycling in the McMurdo Dry Valleys. We will conduct fieldwork at the landscape scale (repeated remote sensing to characterize snow distribution), at the valley and patch scales (quantify snow patch ablation, microbial communities and biogeochemical cycling in subnivian soils). We hypothesize that snow patches play an important role in structuring the spatial distribution of soil microbial communities and their associated ecosystem functioning because of the physical and hydrological influences that snow patches have on the soil environment. The research will contribute to greater public awareness of the importance of polar research to fundamental questions of biology, ecology and hydrology through direct linkages with International Antarctic Institute public outreach activities, including dissemination of web-based learning units on environmental science and microbiology, targeted as resources for secondary and post-secondary educators. Three graduate students, one postdoctoral scholar and multiple undergraduates will participate in the research activities.