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Timing and structure of vegetation, fire, and climate changes on the Pacific slope of northwestern Patagonia since the last glacial termination
Quaternary Science Reviews ( IF 3.2 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.quascirev.2020.106328
Patricio I. Moreno

Abstract By virtue of its location in the southern mid-latitudes, northwestern Patagonia (40°-44°S) offers the opportunity to unravel the mechanisms involved in the initiation and propagation of paleoclimate signals of hemispheric and global significance. Of particular importance is deciphering the evolution of the Southern Westerly Winds (SWW) considering their influence at continental, zonal, hemispheric, and global scale. Here I present a multi-decadal record from Lago Proschle, a small closed-basin lake located on the Pacific slope of northwestern Patagonia, to examine the timing and structure of vegetation, fire, and climate change along a continuum since the onset of the Last Glacial Termination (T1). The record shows rapid glacier recession during T1, reaching the western Andean foothills in ∼400 years or less. Nothofagus-dominated forests established between ∼17.4–17 ka, followed by closed-canopy North Patagonian Rain Forests (NPRF) with shade-tolerant thermophilous trees between ∼16.3–15.4 ka. These changes suggest an abrupt warming trend and an increase in precipitation at ∼16.3 ka, associated with a northward shift of the SWW. Subsequent increases in cold-tolerant hygrophilous trees between ∼15.4–12.8 ka imply a shift to cold, more humid conditions during the Antarctic Cold Reversal, suggesting stronger SWW influence. This was followed by stand-replacing fires brought by a sudden decline in summer precipitation at ∼12.8 ka, associated with a millennial-scale southward shift of the SWW which was contemporaneous with the onset of the Younger Dryas. Dominance of thermophilous, summer-drought tolerant Valdivian rainforest trees and high fire activity ensued between ∼10.3–7.8 ka, suggesting peak warmth and overall decline in annual precipitation associated with weakening of the SWW during the early Holocene. A multi-millennial cooling and wetting trend started at ∼7.8 ka, brought by stronger SWW influence, followed by recurrent, centennial-scale variations in temperature and precipitation starting at ∼6.4 ka. Deforestation, fire, and spread of non-native herbs by Chilean/European settlers began during the late 18th century. Abrupt vegetation changes in the Lago Proschle record were driven by rapid climate changes over the last 17,400 years amplified, in some instances, by fire disturbance.

中文翻译:

自末次冰期结束以来巴塔哥尼亚西北部太平洋斜坡植被、火灾和气候变化的时间和结构

摘要 巴塔哥尼亚西北部(40°-44°S)位于中纬度南部,为揭示具有半球和全球意义的古气候信号的产生和传播机制提供了机会。考虑到南西风 (SWW) 在大陆、纬向、半球和全球范围内的影响,解读南西风 (SWW) 的演变尤为重要。在这里,我展示了位于巴塔哥尼亚西北部太平洋斜坡上的一个小型封闭盆地湖 Lago Proschle 的多年代记录,以检查自末次爆发以来植被、火灾和气候变化的时间和结构。冰川终止(T1)。记录显示 T1 期间冰川迅速退缩,在大约 400 年或更短的时间内到达安第斯山脉西部山麓。大约 17.4-17 ka 之间建立了以 Nothofagus 为主的森林,其次是封闭的树冠北巴塔哥尼亚雨林 (NPRF),在 16.3-15.4 ka 之间建立了耐阴嗜热树木。这些变化表明约 16.3 ka 出现突然的变暖趋势和降水增加,这与 SWW 的北移有关。随后在 ~15.4-12.8 ka 之间耐寒的湿性树木的增加意味着在南极冷逆转期间转向寒冷、更潮湿的条件,表明 SWW 影响更强。紧随其后的是由于夏季降水在 12.8 ka 时突然减少而导致的林间更换火灾,这与 SWW 千年尺度的南移有关,这与新仙女木的发生同时发生。嗜热的优势,夏季耐旱的 Valdivian 雨林树木和高火灾活动随后发生在 ~10.3-7.8 ka 之间,这表明在全新世早期与 SWW 减弱相关的年降水量达到峰值和整体下降。由于更强的 SWW 影响,在 ~7.8 ka 开始了一个千年变冷和湿润趋势,随后在 ~6.4 ka 开始出现周期性的百年尺度的温度和降水变化。智利/欧洲定居者的森林砍伐、火灾和非本地草药的传播始于 18 世纪后期。Lago Proschle 记录中植被的突然变化是由过去 17,400 年的快速气候变化驱动的,在某些情况下,还被火灾干扰放大。表明与全新世早期 SWW 减弱相关的年降水量峰值和总体下降。由于更强的 SWW 影响,在 ~7.8 ka 开始了一个千年变冷和湿润趋势,随后在 ~6.4 ka 开始出现周期性的百年尺度的温度和降水变化。智利/欧洲定居者的森林砍伐、火灾和非本地草药的传播始于 18 世纪后期。Lago Proschle 记录中植被的突然变化是由过去 17,400 年的快速气候变化驱动的,在某些情况下,还被火灾干扰放大。表明与全新世早期 SWW 减弱相关的年降水量峰值和总体下降。由于更强的 SWW 影响,在 ~7.8 ka 开始了一个千年变冷和湿润趋势,随后在 ~6.4 ka 开始出现周期性的百年尺度的温度和降水变化。智利/欧洲定居者的森林砍伐、火灾和非本地草药的传播始于 18 世纪后期。Lago Proschle 记录中植被的突然变化是由过去 17,400 年的快速气候变化驱动的,在某些情况下,还被火灾干扰放大。智利/欧洲定居者的森林砍伐、火灾和非本地草药的传播始于 18 世纪后期。Lago Proschle 记录中植被的突然变化是由过去 17,400 年的快速气候变化驱动的,在某些情况下,还被火灾干扰放大。智利/欧洲定居者的森林砍伐、火灾和非本地草药的传播始于 18 世纪后期。Lago Proschle 记录中植被的突然变化是由过去 17,400 年的快速气候变化驱动的,在某些情况下,还被火灾干扰放大。
更新日期:2020-06-01
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