Snow cover regulation of Alpine soil ecosystem carbon release

该博士项目旨在回答和解决3个问题和目标：1。高山环境下不同积雪梯度下土壤碳和常量养分含量及稳定性如何变化？研究植物群落组成，积雪覆盖和土壤CNP含量之间的关系，使用基于调查的方法在对比高山景观。土壤C循环的季节动态是否随积雪梯度而变化？2 .对土壤进行季节性采样，用于微生物群落分析、与CNP周转相关的土壤功能、凋落物分解分析和跨积雪梯度的温室气体测量。积雪覆盖时间的缩短对雪床生境中C循环的影响是什么？基于土壤-植物系统C交换、微生物抗性和恢复力指标（利用温室气体分析（CO2、CH4、N2O）和13c标记基质的翻转和归宿），三个不同高山生境的原位积雪操纵。研究方案第1链将使用标准的土壤和植被取样方法，沿着积雪持续时间的梯度调查一系列高山生境的土壤CNP储量。为了对苏格兰高山栖息地和气候类型有代表性的覆盖，我们将选择3个“案例研究”区域，例如Cairngorm高原，中央高地和西北高地。使用样带方法，将对土壤进行CNP取样，并详细介绍植物群落。与积雪有关的非生物条件将通过现场湿度和温度传感器进行监测。实地调查和抽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，以提供良好的生态和生物地球化学培训。Strand 2将沿着积雪持续时间的梯度详细探讨控制土壤中碳输入、内部碳循环和植物-土壤群落间碳净通量的过程。将使用早期、中期和晚期融化系统，进行季节性采样和有针对性的（融雪）气体通量采样（土壤呼吸、NEE、CH4、N2O）、凋落物分解、微生物群落（PLFA、TRFLP）和功能分析（酶活性、底物矿化）。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1链技术和培训。链3将缩短仪器研究流域中三个对比系统的积雪覆盖期，并且通过跟踪CN交换（如链2），将确定对原位的影响。为了进一步了解碳循环动力学的机理细节，将向土壤中添加13c标记的基质（真菌生物量），然后在环境和除雪处理下添加CO2、DOC和微生物生物量碳。这种方法将把以前的训练扩展到新的稳定同位素探测方法和生态系统操纵技术。合作和影响通过与外部同事合作，将获得培训和跨学科工作（将生物地球化学和植物生态学联系起来），并将有助于巩固和扩大与国际同事（马克斯普朗克耶拿，法国国家科学研究中心Bioemco巴黎）的合作。预计将展示海报和口头演讲，每年参加一次国内会议（例如BES， BSSS），第三年参加一次国际会议（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.