首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Abrupt climate change as an important agent of ecological change in the Northeast U.S. throughout the past 15,000 years
Authors:Bryan N Shuman  Paige Newby  Jeffrey P Donnelly
Institution:1. Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), UMR CNRS 5805 EPOC—OASU—Université de Bordeaux, Allée Geoffroy Saint-Hilaire, Pessac 33615, France;2. Sorbonne Universités (UPMC, Univ. Paris 06)-CNRS-IRD-MNHN, LOCEAN Laboratory, 4 place Jussieu, F-75005 Paris, France;3. NCAS-Climate, University of Reading, UK;4. Barcelona Supercomputing Center, Edifici Nexus II, C/ Jordi Girona, 31, 08034 Barcelona, Spain;5. UMR CNRS 5318 CECI – CERFACS, 42 Avenue G. Coriolis, 31057 Toulouse, France
Abstract:We use a series of tests to evaluate two competing hypotheses about the association of climate and vegetation trends in the northeastern United States over the past 15 kyrs. First, that abrupt climate changes on the scale of centuries had little influence on long-term vegetation trends, and second, that abrupt climate changes interacted with slower climate trends to determine the regional sequence of vegetation phases. Our results support the second. Large dissimilarity between temporally close fossil pollen samples indicates large vegetation changes within 500 years across >4° of latitude at ca 13.25–12.75, 12.0–11.5, 10.5, 8.25, and 5.25 ka. The evidence of vegetation change coincides with independent isotopic and sedimentary indicators of rapid shifts in temperature and moisture balance. In several cases, abrupt changes reversed long-term vegetation trends, such as when spruce (Picea) and pine (Pinus) pollen percentages rapidly declined to the north and increased to the south at ca 13.25–12.75 and 8.25 ka respectively. Abrupt events accelerated other long-term trends, such as a regional increase in beech (Fagus) pollen percentages at 8.5–8.0 ka. The regional hemlock (Tsuga) decline at ca 5.25 ka is unique among the abrupt events, and may have been induced by high climatic variability (i.e., repeated severe droughts from 5.7 to 2.0 ka); autoregressive ecological and evolutionary processes could have maintained low hemlock abundance until ca 2.0 ka. Delayed increases in chestnut (Castanea) pollen abundance after 5.8 and 2.5 ka also illustrate the potential for multi-century climate variability to influence species' recruitment as well as mortality. Future climate changes will probably also rapidly initiate persistent vegetation change, particularly by acting as broad, regional-scale disturbances.
Keywords:
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号