Tephra layers and early warning signals for critical transitions

该项目寻求通过对火山灰层(火山灰)进行新的研究来开发新的陆地表面复原力测量方法。众所周知，植被格局的变化表明陆地表面弹性的变化，并表明接近门槛变化。火山灰的厘米级厚度的形态是由先前存在的植被覆盖形成的，特别是其深度、密度、范围或斑块。因此，当陀螺沉积的深度与先前存在的植被的高度相似时，陀螺沉积层的形态可以用来评估陀螺沉积时的相对陆地表面弹性。研究人员的目标是首先通过研究冰岛最近的火山喷发--2010年的Eyjafjallajökull火山喷发和2011年的Grímsvötn火山喷发--创造出新的恢复力衡量标准。其次，他们将把从最近的火山灰坠落研究中获得的新认识应用到保存在土壤中的许多过去的火山灰层所呈现的自然档案中。衡量地表复原力和接近达到阈值的迹象可对理解人类和环境驱动的变化之间的相互作用以及对可持续性科学不断发展的领域作出重要贡献。在冰岛南部，自斯堪的纳维亚人定居以来，已经沉积了多达21个Tephra层，这些层之间明显地被风成沉淀层隔开。我们知道，这些地区的景观一直受到方向性变化(如气温下降和放牧压力增加)的影响，这些变化将地表推向一种持续状态和另一种持续状态之间的临界点，有时甚至跨越临界点。知不知道？险些失手？在过去，来自新用途的非洲菊草层可以帮助我们了解社区在什么情况下从变化的边缘后退，以及适应和复原力、短期和长期稳健性之间的权衡，以及跨尺度结合的影响。该项目将涉及一个国际化的多学科团队，将理论和方法创新与实地考察和实验室分析相结合，并为早期职业学者提供研究机会。

This project seeks to develop new measures of land surface resilience through a novel study of layers of volcanic ash (tephra). Changes in vegetation patterns are known to indicate changing land surface resilience and indicate proximity to threshold change. The morphology of cm-scale thicknesses of tephra is shaped by the pre-existing vegetation cover, in particular its depth, density, extent or patchiness. Thus, when tephra deposition is of a similar depth to the height of the pre-existing vegetation, tephra layer morphology can be used to assess relative land surface resilience at the time of tephra deposition. The researchers aim to develop new measures of resilience firstly through study of tephra layers created by recent Icelandic eruptions- the 2010 eruption of Eyjafjallajökull and the 2011 eruption of Grímsvötn. Secondly, they will apply the new understandings gained from the study of very recent ash falls to the natural archive presented by the numerous past tephra layers preserved within the soil. Measures of land surface resilience and indications of proximity to threshold-crossing could make important contributions to understanding the interplay of changes driven by people and by the environment, and to the evolving field of sustainability science. In southern Iceland up to 21 tephra layers have been deposited since the Norse settlement, and these layers are clearly separated by intervening layers of aeolian sediment. We know that landscapes in these areas have been subject to directional drivers of change (such as falling temperatures and increasing grazing pressures) that have pushed land surfaces close to, and at times across, tipping points between one persistent state and another. Knowledge of ?near misses? in the past derived from novel uses of tephra layers could help us to understand the circumstances under which communities backed away from the brink of change, and the tradeoffs between adaptation and resilience, short term and long term robustness, and the effects of cross-scale conjunctures. This project will involve an international, multidisciplinary team, combine theoretical and methodological innovation with fieldwork and laboratory analysis, and provide research opportunities for early career scholars.