Tephra layers and early warning signals for critical transitions

Tephra 层和关键转变的预警信号

• 批准号: 1249313
• 负责人: Andrew Dugmore
• 金额: $ 10.26万
• 依托单位: CUNY Graduate School University Center
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1249313&HistoricalAwards=false
• 关键词: Tephra; layers; early; warning; signals

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.

该项目旨在通过对火山灰层的新研究，制定新的地表恢复措施。 已知植被格局的变化表明地表恢复力的变化，并表明接近阈值变化。火山灰的厘米级厚度的形态是由预先存在的植被覆盖，特别是其深度，密度，范围或斑块形成。因此，当火山灰沉积是一个类似的深度预先存在的植被的高度，火山灰层的形态可以用来评估在火山灰沉积的时间相对陆地表面的弹性。研究人员的目标是首先通过研究最近冰岛火山爆发产生的火山灰层-2010年Eyjafjallajökull火山爆发和2011年Grímsvötn火山爆发-来开发新的恢复措施。其次，他们将把从最近的火山灰福尔斯研究中获得的新认识应用于土壤中保存的许多过去火山灰层所呈现的自然档案。衡量地表复原力和接近临界点的迹象可为理解人与环境驱动的变化的相互作用以及不断发展的可持续性科学领域做出重要贡献。自挪威人定居以来，冰岛南部已沉积了多达21层火山灰层，这些层明显被风成沉积物层隔开。我们知道，这些地区的景观一直受到方向性变化驱动因素的影响（如气温下降和放牧压力增加），这些因素将土地表面推近，有时甚至跨越一个持续状态与另一个持续状态之间的临界点。 什么知识？差点失手在过去，从火山灰层的新用途中获得的信息可以帮助我们了解社区从变化的边缘退缩的情况，以及适应和恢复力，短期和长期鲁棒性之间的权衡，以及跨尺度结合的影响。 该项目将涉及一个国际性的多学科团队，将联合收割机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。