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


Permian polar forests: deciduousness and environmental variation
Authors:E L Gulbranson  J L Isbell  E L Taylor  P E Ryberg  T N Taylor  P P Flaig
Institution:1. Department of Geosciences, University of Wisconsin‐Milwaukee, , Milwaukee, WI, USA;2. Department of Ecology and Evolutionary Biology, Natural History Museum and Biodiversity Institute, University of Kansas, , Lawrence, KA, USA;3. Division of Paleobotany, Natural History Museum and Biodiversity Institute, University of Kansas, , Lawrence, KS, USA;4. Bureau of Economic Geology, University of Texas‐Austin, , Austin, TX, USA
Abstract:Forests are expected to expand into northern polar latitudes in the next century. However, the impact of forests at high latitudes on climate and terrestrial biogeochemical cycling is poorly understood because such forests cannot be studied in the modern. This study presents forestry and geochemical analyses of three in situ fossil forests from Late Permian strata of Antarctica, which grew at polar latitudes. Stem size measurements and stump spacing measurements indicate significant differences in forest density and canopy structure that are related to the local depositional setting. For forests closest to fluvial systems, tree density appears to decrease as the forests mature, which is the opposite trend of self‐thinning observed in modern forests. We speculate that a combination of tree mortality and high disturbance created low‐density mature forests without understory vegetation near Late Permian river systems. Stable carbon isotopes measured from permineralized wood in these forests demonstrate two important points: (i) recently developed techniques of high‐resolution carbon isotope studies of wood and mummified wood can be applied to permineralized wood, for which much of the original organic matter has been lost and (ii) that the fossil trees maintained a deciduous habit at polar latitudes during the Late Permian. The combination of paleobotanical, sedimentologic, and paleoforestry techniques provides an unrivaled examination of the function of polar forests in deep time; and the carbon isotope geochemistry supplements this work with subannual records of carbon fixation that allows for the quantitative analysis of deciduous versus evergreen habits and environmental parameters, for example, relative humidity.
Keywords:
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