Snow cover regulation of Alpine soil ecosystem carbon release

本博士项目旨在回答和解决三个问题和目标：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不同的雪盖梯度上变化？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跨越不同的高山景观。土壤碳循环的季节动态是否在不同的雪盖梯度上有所不同？土壤微生物群落分析的季节性采样、与CNP周转有关的土壤功能、凋落物分解分析和跨雪覆盖坡度的温室气体测量。雪层覆盖时间的缩短对雪床栖息地的C自行车有什么影响？在三个不同的高山生境中的原位积雪操作，遵循土壤-植物系统中的C交换，以及使用温室气体分析(CO2，CH4，N2O)的微生物阻力和弹性指标，以及13C标记底物的周转和命运。研究计划Strand 1将使用标准的土壤和植被采样方法，沿积雪覆盖持续时间的梯度调查一系列高山生境中的土壤CNP储量。为了对苏格兰高山生境和气候类型有代表性的报道，我们将选择3个‘案例研究’地区，例如凯恩戈姆高原、中央高地和西北高地。使用样带方法，将对土壤进行CNP采样，并对植物群落进行详细说明。将使用现场湿度和温度传感器监测与积雪相关的非生物条件。现场调查和采样技术将与详细的样品分析和使用实验室中的标准分析程序相结合，以提供健全的生态和生物地球化学培训。链2将详细探讨控制C输入到土壤的过程、内部C循环以及沿雪地持续时间的梯度向/来自植物-土壤群落的C的净通量。利用早期、中期和晚期融化系统，将对气体通量(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)进行季节性采样和有针对性的(融雪)采样。关于微生物群落分析技术以及功能计量分析的培训，以及使用现场和实验室方法(即IRGA、GC)的气体交换，将延伸第1股技术和培训。第三股将缩短仪表化研究流域中三个不同系统的积雪期，并通过遵循CN交换(如第二股)，将查明现场影响。为了扩展碳周转动态的机理细节，将在土壤中添加13C标记的底物(真菌生物量)，然后在环境和除雪处理下添加二氧化碳、DOC和微生物生物量碳。这一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纵技术。合作和影响培训以及跨学科工作(将生物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而获得，并将帮助巩固和扩大与国际同事的合作(Max Planck Jena，CNRS Bioemco Paris)。预计将提供招贴画和口头演讲，每年出席国内会议(例如，BES、BSSS)，并参加第三年的国际会议(例如，EGU、Bioggomon)。

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.