Tree-ring analysis and conifer growth responses to increased atmospheric CO2 levels |
| |
Authors: | Felix Kienast Robert J Luxmoore |
| |
Institution: | (1) Environmental Sciences Division, Oak Ridge National Laboratory, 37831 Oak Ridge, TN, USA;(2) Present address: Swiss Federal Institute of Forestry Research, 8903 Birmensdorf, Switzerland |
| |
Abstract: | Summary Tree-ring data of naturally grown connifers were analyzed to evaluate the possibility of enhanced tree growth due to increased atmospheric CO2. Tree cores were obtained from 34 sites in four different climatic regions in the northern hemisphere. In each of the four regions, the sampling sites were located along ecological gradients between the subalpine treeline and low elevations and, sometimes, the arid forest border. Growth trends after 1950, when the atmospheric CO2 concentration increased by more than 30 l·l-1 indicate an increase in ring-widths at eight of the 34 sites. These chronologies were from sites which moderate temperature or water stress. In four cases the growth increase in the post-1950 period coincided with favorable climatic conditions. In the remaining four cases, the growth increase exceeded the upper bound response expected from CO2 enrichment experiments with seedling conifer species. Therefore, increased growth in any of the tree-ring chronologies examined could not be solely attributed to higher atmospheric CO2 concentrations.Major financial supporters: Swiss National Science Foundation (application no. 1.869-0.83); Swiss Federal Institute of Forestry Research, 8903 Birmensdorf, Switzerland; other financial supporters: Carbon Dioxide Research Division, U.S. Department of Energy under subcontract no. 11X-57507V with Martin Marietta Energy Systems, IncOperated by Martin Marietta Energy Systems, Inc., under contract DE-AC05-840R21400 with U.S. Department of Energy |
| |
Keywords: | X-ray densitometry CO2 fertilization -factor" target="_blank">gif" alt="beta" align="MIDDLE" BORDER="0">-factor |
本文献已被 SpringerLink 等数据库收录! |
|