Savanna Soil Carbon: investigating biological climate resilience

稀树草原生态系统占地球陆地面积的20%，其特点是热带和亚热带地区有季节性降雨的开阔的林地-草原混交林。它们也是全球重要的生物多样性和碳的储存库，受到放牧、火灾和气候的综合影响。稀树草原对人类的生计和福祉至关重要，有超过10亿人依赖这些景观提供的资源或服务。这些措施包括从天然和管理的稀树草原生态系统提供食物、燃料和纤维。稀树草原和人类的共同进化已经发生了200,000多年。土壤支持着这些环境的形式和功能的交付和可持续性，土壤生物群落积极地调节着生物群规模的植被动态、温室气体排放和碳固存。然而，这些古老而有价值的系统正受到越来越多的人类活动和过度开采以及火灾和气候制度变化的压力。这些驱动因素共同具有显着改变稀树草原生物多样性和生物地球化学功能的能力，并对依赖的人类福祉和幸福产生影响。具体地说，关于这些现象对底层土壤的生物和生物地球化学弹性的潜在个别和交互影响，存在相当大的不确定性。这项博士研究的目的将是提高对放牧、火灾和气候变化对稀树草原土壤生物学、碳生物地球化学和对未来干扰的适应能力的个体和交互影响的理解。研究将集中在南非的稀树大草原生态系统，这些生态系统是全球发现的典型的亚热带季节性旱地。具体目标和活动将包括：1.确定不同稀树草原退化梯度土壤性质的变异性。2.研究放牧/火/气候相互作用对田间土壤性质和功能的影响。3.测试稀树草原土壤对气候胁迫和物理干扰的生物和功能恢复能力。方法-将与来自威特沃特斯兰德大学、南非比勒陀利亚大学、兰开斯特大学和利弗普尔大学的研究人员合作，使用一系列植物-土壤田间、实验和实验室技术。学生培训将确保具体的研究和可转让的技能发展，包括：土壤生态学和生物地球化学、微生物分子技术、温室气体采样和分析、同位素科学、实验设计、统计学、科学写作、研究报告/发表、项目管理、财务监督和审查、团队合作、高级自主学习、人员和时间管理、网络、国际研究。

Savanna ecosystems occupy 20% of the Earth's land surface and are characterized by open canopied mixed woodland-grassland with seasonal rainfall in tropical and sub-tropical regions. They are also reservoirs of globally important biodiversity and carbon that are strongly influenced by the combined effects of grazing, fire and climate. Savannas are critical for human livelihoods and wellbeing, with over 1 billion people reliant on resources or services that these landscapes provide. These include the provision of food, fuel and fibre from natural and managed savanna ecosystems. The co-evolution of savannas and humans has occurred over 200,000 years.Soils underpin the delivery and sustainability of the form and function of these environments with soil biotic communities actively regulating biome scale vegetation dynamics, greenhouse gas emissions, and carbon sequestration. These ancient and valuable systems are, however, under pressure from increasing human activity and over-exploitation and changes in fire and climatic regimes. Together these drivers have the capacity to significantly alter savanna biodiversity and biogeochemical function with implications for dependent human welfare and happiness. Specifically, there is considerable uncertainty regarding the potential individual and interactive impacts of these phenomena on the biological and biogeochemical resilience of the underlying soils. The aim of this PhD research will be to improve understanding of the individual and interactive effects of grazing, fire and climate change on savanna soil biology, carbon biogeochemistry and resilience to future disturbance. Research will be focused on savanna ecosystems in South Africa that typify sub-tropical seasonal drylands found across the planet. Specific objectives and activities will include: 1. To determine the variability in soil properties across savanna degradation gradients. 2. To examine the effects of grazing/fire/climate interactions on soil properties and functions in the field. 3. To test the biotic and functional resilience of savanna soils to climate stress and physical disturbance. Approach - A range of plant-soil field, experimental and laboratory techniques will be used in collaboration with researchers from University of Witwatersrand, and Pretoria University in South Africa, the UKCEH at Lancaster and University of Liverpool.Student training will ensure specific research and transferable skills development that include; soil ecology and biogeochemistry, microbial molecular techniques, greenhouse gas sampling and analyses, isotope science, experimental design, statistics, scientific writing, research presentation/publication, project management, financial oversight and review, team working, advanced independent learning, people and time management, networking, international research.