Shrub-driven transformation of the alpine soil carbon cycle

灌木驱动的高山土壤碳循环转变

• 批准号: NE/Z000297/1
• 负责人: Richard Bardgett
• 金额: $ 105.6万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FZ000297%2F1
• 关键词: Shrub; driven; transformation; alpine; soil

Ecosystems worldwide are experiencing rapid shifts in vegetation in response to climate change. One of the most pervasive, but poorly studied, vegetation shifts is occurring in alpine regions of the world, where climate change is taking place at almost double the rate of the northern hemisphere average. In combination with changes in land use, this is leading to the rapid and widespread upward expansion of woody ericaceous shrubs into alpine grasslands, with potential far-reaching, but poorly understood, consequences for the functioning of these fragile high-altitude ecosystems. A pressing uncertainty concerns the potential for ericaceous shrubs to transform processes of soil (C) cycling in alpine grasslands, with implications for soil C storage and persistence. The need to address this uncertainty couldn't be more urgent given that alpine grassland soils represent a major global C store, and because even small changes in their soil C storage capacity could have major implications for C-cycle feedbacks to climate change. Tackling this challenge requires a step change in our understanding of the mechanisms underpinning shrub-driven transformations of soil organic matter (SOM) and its persistence, a critical ecosystem property determining the response of soil C to global change.We posit that the widespread and rapid upward expansion of ericaceous shrubs and their root-associated ericoid mycorrhizal fungi into alpine grassland triggers distinct rhizosphere pathways that lead to the suppression of SOM decomposition and formation of persistent SOM, thereby stabilising the soil C pool and reducing soil C loss under future climate change. We also expect these pathways of soil C gain and stabilisation to outweigh opposing rhizosphere pathways that cause soil C loss, thereby leading to net C gain. We plan to test our novel hypotheses using a powerful combination of landscape, plot, and laboratory studies with advanced stable-isotope, genomics, and biochemical approaches to interrogate the relative roles of contrasting rhizosphere-driven pathways of SOM decomposition and stabilisation of C in alpine grassland. Moreover, we build on our past NERC funded research in alpine grasslands, including a long-term experimental platform in the Austrian Alps, and we draw on novel concepts and discoveries concerning the pathways by which rhizosphere-driven processes regulate the persistence of soil C. Our study will break new ground by identifying novel mechanisms by which rapid and widespread ericaceous shrub expansion alters the balance of rhizosphere pathways that regulate soil C gain and loss in alpine grasslands, ultimately determining soil C storage and C-cycle feedbacks. But also, it will push the frontiers of understanding the role of rhizosphere-driven processes as regulators of soil C storage and persistence, which is a fast moving, but poorly understood area of science of central importance to the global C balance and mitigation of climate change.

全世界的生态系统正在响应气候变化而经历植被的快速变化。植被转移是世界上高山地区发生的最普遍但研究较少的植被转移之一，气候变化的发生率几乎是北半球平均水平的两倍。结合土地利用的变化，这导致木本埃里西斯灌木迅速而广泛地向上扩展到高山草原上，潜在的深远但知之甚少，但对这些脆弱的高蓝色生态系统的功能产生了影响。紧迫的不确定性涉及ericace灌木转化土壤过程（C）在高山草原中循环的潜力，这对土壤C的储存和持久性产生了影响。考虑到高山草原土壤代表着主要的全球C商店，解决这种不确定性的需求并不是更紧迫的，并且由于其土壤C存储能力的微小变化也可能对C-Cycle反馈对气候变化产生重大影响。应对这一挑战需要改变我们对基础灌木有机物（SOM）的机制的理解及其持久性，这是一个关键的生态系统属性，确定土壤C对全球变化的响应。我们认为，广泛而快速ericaceous灌木及其根相关的ericoid霉菌真菌向上扩展到高山草原上，触发了不同的根际途径，导致抑制SOM分解并形成持续的SOM，从而稳定土壤C池并减少未来气候变化。我们还期望这些土壤C增益和稳定的途径大于相对的根际途径，从而导致土壤C损失，从而导致C净获得净收益。我们计划使用高级稳定 - 同位素，基因组学和生化方法的景观，情节和实验室研究的强大组合来测试我们的新假设草原。此外，我们基于我们过去的NERC资助的高山草原研究，包括奥地利阿尔卑斯山中的长期实验平台，我们借鉴了有关根茎驱动过程调节土壤C持续性的新颖概念和发现。我们的研究将通过识别新的机制来打破新的基础，通过这种机制，快速和广泛的埃里西斯灌木的扩张改变了根际途径的平衡，而根际途径的平衡，这些途径调节了高山草原的土壤c增益和损失，最终确定土壤C储存和C循环反馈。但是，这也将推动前沿理解根际驱动过程作为土壤c存储和持久性的调节者的作用，这是一个快速移动的，但对全球C平衡和缓解气候的科学重要性方面的了解却很差改变。