The development and function of subarctic alpine soil surface biological communities

由于生物结皮群落的普遍分布和独特的生理特征，生物结皮群落的建立和关键生态系统功能的启动是一个常见的早期演替过程。在高山和北极环境中，BSCs通常是主要的植被单元，这使得这些生态系统成为研究BSCs在陆地生态系统发展中的作用的独特有力的模型。我的长期目标是确定bsc -土壤表面界面驱动北极和高山环境中养分循环过程的机制。BSCs位于土壤-大气界面，其发育轨迹受小气候和土壤理化因子共同驱动。随着这些土壤表面组合的建立，它们反过来通过在BSCs和壳下土壤之间的生物地球化学界面启动关键的生态系统功能来调节其环境。在接下来的5年里，我的短期目标是将平衡计分卡关键组分的生态位与平衡计分卡-土壤界面养分循环过程的启动和调节联系起来。我的具体目标是：1)基于已实现的主要宏观和微观生物门的生态位，建立BSC群落的演替模型；2)研究与土壤物理、化学和微生物特性相关的平衡记分卡组合的发育和功能；3)将平衡计分卡的发展与平衡计分卡和壳下土壤微生物群落驱动的生态系统水平的养分循环联系起来。***使用冰川前田（即冰川消退逐渐暴露的地区）作为理想的时间序列系统，我将进行观测和操作调查，以确定和确认关键BSC组成部分的实现生态位。此外，我将使用操纵性生长室实验来更仔细地研究BSCs与物理，化学和微生物土壤特性之间的相互作用。为了更好地描述BSCs和壳下土壤微生物群落在养分转移和转化中的作用，我将在微观研究中研究同位素标记的C、N和P的吸收和运动。将调查生态系统组成部分（即结皮、土壤、地上和地下维管植物）、BSC和结皮下土壤微生物群落之间的营养运动。通过确定BSC群落如何发展并反过来改变土壤环境，拟议的研究将促进我们对早期演替过程和恢复促进长期生态系统健康途径的能力的理解。

Due to their ubiquitous distribution and unique physiology, establishment of biological soil crust (BSC) communities and corresponding initiation of key ecosystem functions is a common early successional process. In alpine and arctic environments, BSCs are often a dominant vegetation unit, making these ecosystems a uniquely powerful model for examining the role of BSCs in terrestrial ecosystem development. My long-term goal is to identify mechanisms at the BSC-soil surface interface that drive nutrient cycling processes in arctic and alpine environments. BSCs are located at the soil-atmosphere interface where their developmental trajectories are driven by both microclimate and soil physicochemical factors. As these soil surface assemblages establish, they in turn modulate their environment through the initiation of key ecosystem functions at biogeochemical interfaces between BSCs and below-crust soils. Over the next 5 years my short-term goal is to link the realized niches of key BSC components with the initiation and modulation of nutrient cycling processes at the BSC-soil interface. My specific objectives are to: 1) develop successional models of BSC communities based upon the realized niche of primary macro and micro BSC phyla; 2) examine the development and function of BSC assemblages in relation to soil physical, chemical and microbial properties; and 3) relate BSC development to ecosystem-level nutrient cycling driven by BSC and below-crust soil microbial communities. ***Using glacial forefields (i.e. areas progressively exposed by a receding glacier) as ideal chronosequence systems, I will conduct both observational and manipulative investigations to determine and confirm the realized niche of key BSC components. In addition, I will use manipulative growth chamber experiments to more closely examine the interactions between BSCs and physical, chemical and microbial soil properties. To better characterize the role BSCs and below-crust soil microbial communities play in nutrient transfer and transformations, I will examine the uptake and movement of isotopically labelled C, N and P in microcosm studies. Nutrient movement both between ecosystem components (i.e. crusts, soils, above and belowground vascular plants), and BSC and below-crust soil microbial communities will be investigated. By determining how BSC communities develop and in turn modify the soil environment, the proposed research will advance our understanding of early successional processes and ability to restore pathways that promote long-term ecosystem health.