Snow cover regulation of Alpine soil ecosystem carbon release

这个博士项目旨在回答和解决3个问题和目标：1。在高山环境中，土壤碳和常量营养素含量和稳定性如何在积雪梯度上变化？研究植物群落组成之间的关系，积雪，和土壤CNP含量使用调查为基础的方法在对比高山植被。土壤碳循环的季节动态是否随积雪梯度而变化？季节性土壤采样，用于微生物群落分析、与CNP周转相关的土壤功能、凋落物分解测定和跨积雪梯度的温室气体测量。在雪床生境中，积雪覆盖时间的减少对碳循环有什么影响？原位雪操作在三个对比高山栖息地，以下C交换在土壤-植物系统中，和微生物的抵抗力和弹性指标使用温室气体分析（CO2，CH 4，N2 O），和营业额和命运的13 C-标记substrates.Programme of researchStrand 1将使用标准的土壤和植被采样方法，调查土壤CNP股票在一系列高山栖息地沿着梯度的积雪覆盖时间。为了有苏格兰高山栖息地和气候类型的代表性，我们将选择3个“案例研究”地区，例如Cairngorm高原，中部高地和西北高地。采用横断面方法，对土壤进行采样，以进行CNP，并详细描述植物群落。与积雪有关的非生物条件将用原位湿度和温度传感器进行监测。实地调查和取样技术将与详细的样品分析和实验室标准分析程序的使用相结合，以提供合理的生态和地球化学培训。链2将详细探讨控制C输入到土壤中的过程，内部C循环和净通量的C到/从植物-土壤群落沿着梯度的雪层持续时间。使用早期、中期和晚期融化系统，将进行季节性采样和气体通量（土壤呼吸、NEE、CH 4、N2 O）、凋落物分解、微生物群落（PLFA、TRFLP）和功能测定（酶活性、底物矿化）的目标（融雪）采样。关于微生物群落分析技术以及功能指标分析的培训，以及使用现场和实验室方法（即IRGA，GC）的气体交换将扩展第1链技术和培训。第3股将缩短在三个对比系统的积雪期在仪表研究集水区，并通过以下氯化萘交换（如在第2股），现场影响将被确定。为了扩展C周转动力学的机制细节，将添加到土壤中的13 C标记的底物（真菌生物量），然后在环境和除雪处理下的CO2，DOC和微生物生物量碳。这种方法将把以前的培训扩展到新的稳定同位素探测方法和生态系统操作技术。合作和影响培训和跨学科工作（将地球化学和植物生态学联系起来）将通过与外部同事的合作获得，并将有助于巩固和扩展与国际同事的合作（马克斯普朗克耶拿，CNRS Bioemco巴黎）。预计将提交海报和口头演讲，每年参加一次国内会议（例如BES，BSSS），第三年参加国际会议（例如EGU，Biogeomon）。

This PhD project aims to answer and address 3 questions and objectives:1. How does soil carbon and macronutrient content and stability vary across snow cover gradients in the alpine environment? Examine relationships between plant community composition, snow cover, and soil CNP content using a survey-based approach across contrasting alpine landscapes.2. Do the seasonal dynamics of soil C cycling vary across snow-cover gradients? Seasonal sampling of soils for microbial community analysis, soil functions associated with CNP turnover, litter decomposition assays, and greenhouse gas measurements across snow-cover gradients.3. What are the effects of reduced snow-cover duration on C cycling in snow-bed habitats? In situ snow manipulation in three contrasting alpine habitats, following C exchange in the soil-plant system, and microbial resistance and resilience metrics using GHG analysis (CO2, CH4, N2O), and turnover and fate of 13C-labelled substrates.Programme of researchStrand 1 will use standard soil and vegetation sampling approaches to investigate soil CNP stocks in a range of alpine habitats along gradients of snow cover duration. To have a representative coverage of Scottish alpine habitats and climate types, we will select 3 'case study' areas, e.g. the Cairngorm plateau, central highlands and north-west highlands. Using a transect approach, soils will be sampled for CNP, and the plant community detailed. Abiotic conditions associated with snow cover will be monitored with in situ moisture and temperature sensors. Techniques of field survey and sampling will be combined with detailed sample analysis and use of standard analytical procedures in the lab to provide sound ecological and biogeochemical training. Strand 2 will explore in detail the processes controlling C input to the soil, internal C cycling and net fluxes of C to/from plant-soil communities along a gradient of snow-lie duration. Using early, middle, and late melting systems, seasonal sampling, and targeted (snowmelt) sampling of gas flux (Soil Respiration, NEE, CH4, N2O), litter decomposition, microbial community (PLFA, TRFLP) , and functional assays (Enzyme activity, substrate mineralisation) will be performed. Training on microbial community analysis techniques alongside functional metrics assays, as well as gas exchange using field and laboratory methods (i.e. IRGA, GC) will extend strand 1 techniques and training. Strand 3 will shorten the snow-cover period in three contrasting systems in the instrumented study catchment, and by following CN exchange (as in strand 2), in situ impacts will be ascertained. To extend mechanistic detail on the dynamics of C turnover, a 13C-labelled substrate (fungal biomass) will be added to the soil, and followed in CO2, DOC and microbial-biomass carbon under ambient and snow-removal treatments. This approach will extend previous training into novel stable isotope probing methodologies and ecosystem manipulations techniques.Collaboration and ImpactTraining, and interdisciplinary work (linking biogeochemistry and plant ecology) will be gained through working with external colleagues, and will aid in cementing, and extending collaborations with international colleagues (Max Planck Jena, CNRS Bioemco Paris). Presentation of posters and oral talks is expected, with yearly attendance of a domestic conference (e.g. BES, BSSS), and year 3 attendance at an international (e.g. EGU, Biogeomon) conference.