The use of dendrochronology to study and date geomorphic processes in volcanic environments is still incipient, even more so on the volcanic slopes covered by temperate forests in central Mexico. Mass movements, such ...The use of dendrochronology to study and date geomorphic processes in volcanic environments is still incipient, even more so on the volcanic slopes covered by temperate forests in central Mexico. Mass movements, such as debris flows, often impact forest stands where they cause damage to individual trees, thereby generating growth disturbances(GD) in the tree-ring records. The identification and dating of GD enables reconstruction of the age of trees colonizing bare surfaces after major events, but also allows the assessment of the frequency or spatial distribution of past geomorphic process activity. Here we used increment cores from 65 Pinus leiophylla, Abies religiosa, and Alnus jorullensis trees growing in the Axal gorge, on the southern slopes of La Malinche volcano, to unravel past debris-flow activity both temporally and spatially. Based on the combination of GD records, a weighted tree response index(Wit), field evidence and hydrometeorological records, we reconstructed 23 debris flows since 1933.Interestingly, almost two-thirds of the reconstructed years with debris-flow activity in Axal gorge match with events recorded in Axaltzintle gorge located on the NE slopes of La Malinche. These findings suggest a regional triggering mechanism, most likely related to the occurrence of hurricanes. This research could be useful for disaster risk management of the La Malinche National Park.展开更多
The“Third Pole”usually refers to the Tibetan Plateau and surroundings as it is the largest glaciated zone on Earth after the Antarctic and Arctic[1].It is also one of the major hotspots in the world suffering from w...The“Third Pole”usually refers to the Tibetan Plateau and surroundings as it is the largest glaciated zone on Earth after the Antarctic and Arctic[1].It is also one of the major hotspots in the world suffering from widespread and severe glacial lake outburst flood(GLOF)hazard[2,3].展开更多
Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this ex...Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE. After cross-dating and double-staining, we identified 89Blue Rings(lack of cell wall lignification), nine Frost Rings(cell deformation and collapse), and 93Light Rings(reduced cell wall thickening) in the Northern Hemisphere. Our network reveals evidence for the strongest temperature depression between mid-July and early-August 536 CE across North America and Eurasia, whereas more localised cold spells occurred in the summers of 532, 540–43, and548 CE. The lack of anatomical signatures in the austral trees suggests limited incursion of stratospheric volcanic aerosol into the Southern Hemisphere extra-tropics, that any forcing was mitigated by atmosphere-ocean dynamical responses and/or concentrated outside the growing season, or a combination of factors. Our findings demonstrate the advantage of wood anatomical investigations over traditional dendrochronological measurements, provide a benchmark for Earth system models, support cross-disciplinary studies into the entanglements of climate and history, and question the relevance of global climate averages.展开更多
文摘The use of dendrochronology to study and date geomorphic processes in volcanic environments is still incipient, even more so on the volcanic slopes covered by temperate forests in central Mexico. Mass movements, such as debris flows, often impact forest stands where they cause damage to individual trees, thereby generating growth disturbances(GD) in the tree-ring records. The identification and dating of GD enables reconstruction of the age of trees colonizing bare surfaces after major events, but also allows the assessment of the frequency or spatial distribution of past geomorphic process activity. Here we used increment cores from 65 Pinus leiophylla, Abies religiosa, and Alnus jorullensis trees growing in the Axal gorge, on the southern slopes of La Malinche volcano, to unravel past debris-flow activity both temporally and spatially. Based on the combination of GD records, a weighted tree response index(Wit), field evidence and hydrometeorological records, we reconstructed 23 debris flows since 1933.Interestingly, almost two-thirds of the reconstructed years with debris-flow activity in Axal gorge match with events recorded in Axaltzintle gorge located on the NE slopes of La Malinche. These findings suggest a regional triggering mechanism, most likely related to the occurrence of hurricanes. This research could be useful for disaster risk management of the La Malinche National Park.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA19030301,XDA20030101)A special acknowledgment is to China-Pakistan Joint Research Center on Earth Sciences that supported the implementation of this study.Guoxiong Zheng thanks the China Scholarship Council for supporting his visit to the University of Geneva from February 2019 to February 2021(201804910569).
文摘The“Third Pole”usually refers to the Tibetan Plateau and surroundings as it is the largest glaciated zone on Earth after the Antarctic and Arctic[1].It is also one of the major hotspots in the world suffering from widespread and severe glacial lake outburst flood(GLOF)hazard[2,3].
基金funding from the ERC Advanced Project MONOSTAR (Ad G 882727)funding from Sust ES: adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_0 19/0000797)+11 种基金funding from the Fritz & Elisabeth Schweingruber Foundation. Duncan A. Christie and Carlos Le Quesne received funding from the ANID (FONDECYT 1201411, 1221307, FONDAP 15110009, BASAL FB210018)funding from the Russian Science Foundation grant (RSF 21-17-00006)funding from NSF Arctic Social Science 2112314NSF Arctic Natural Science 2124885the NSF P2C2 (Paleo Perspectives on Climatic Change) program (various grants)funding from the Russian Science Foundation grant (RSF 21-1400330)funding from the Russian Science Foundation grant (RSF 18-14-00072P)supported by the Swedish Research Council (201801272)funding from the Swiss National Science Foundation through the SNSF Sinergia CALDERA project (CRSII5 183571)funding from the National Science Foundation’s P2C2 Program (1902625 and 1203749)the Malcolm H.Wiener Foundationfunded through NSF P2C2 Program (2002454)
文摘Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE. After cross-dating and double-staining, we identified 89Blue Rings(lack of cell wall lignification), nine Frost Rings(cell deformation and collapse), and 93Light Rings(reduced cell wall thickening) in the Northern Hemisphere. Our network reveals evidence for the strongest temperature depression between mid-July and early-August 536 CE across North America and Eurasia, whereas more localised cold spells occurred in the summers of 532, 540–43, and548 CE. The lack of anatomical signatures in the austral trees suggests limited incursion of stratospheric volcanic aerosol into the Southern Hemisphere extra-tropics, that any forcing was mitigated by atmosphere-ocean dynamical responses and/or concentrated outside the growing season, or a combination of factors. Our findings demonstrate the advantage of wood anatomical investigations over traditional dendrochronological measurements, provide a benchmark for Earth system models, support cross-disciplinary studies into the entanglements of climate and history, and question the relevance of global climate averages.
