植物生态学报 2010, 34 (9): 1045–1057 doi: 10.3773/j.issn.1005-264x.2010.09.005 Chinese Journal of Plant Ecology 川西卧龙国家级自然保护区树木生长对气候响应的时间稳定性评估李宗善1刘国华1*傅伯杰1张齐兵2胡婵娟1罗淑政11中国科学院生态环境研究中心城市与区域生态国家重点实验室, 北京 100085; 2中国科学院植物研究所植被与环境变化国家重点实验室, 北京100093摘要根据川西卧龙地区岷江冷杉(Abies faxoniana)的年轮宽度资料, 分析了该地区树木生长特征及对气候响应在最近53年(1956–2008年)的异质性特征。
结果表明, 在1956–1976年时段, 树木生长速率较快, 晚冬至早春(1月到4月)温度对树木生长有着明显的促进作用, 而春末5月份的高温对于树木生长有限制性影响, 而与日照时数关系不大; 在1977–2008年时段, 树轮生长主要受冬季(11月到1月)低温的限制, 另外, 日照时数对于树木生长的限制性影响明显增强。
秋季到早冬(9–12月)降水在两个时段上对树木生长均有一定的限制性影响。
树轮指数在1956–1976年时段与温度序列吻合较好, 而在1977–2008年时段树轮指数明显偏低, 与温度序列出现了明显的分离。
1977–2008年时段内云层覆盖量增加导致太阳辐射量显著下降, 进而树木可利用的光合有效辐射也相应地降低, 这可能是树木生长速率在此时期明显较慢的主要原因。
关键词气候响应, 树木年轮, 川西地区, 卧龙国家级自然保护区Evaluation of temporal stability in tree growth-climate response in Wolong National Natural Reserve, western Sichuan, ChinaLI Zong-Shan1, LIU Guo-Hua1*, FU Bo-Jie1, ZHANG Qi-Bing2, HU Chan-Juan1, and LUO Shu-Zheng11State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085, China; and 2State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, ChinaAbstractAims It is generally assumed in dendroclimatological studies that the approximate relationship between tree growth and the limiting climatic factors is stable over time. However, observed spatial and temporal instabilities in growth-climate relationships suggest diverse growth responses expected to be triggered by unprecedented climatic changes in the future may greatly complicate dendroclimatic reconstructions of past climate histories. We test the stability of the growth-climate relationship using tree ring-width data of Abies faxoniana in Wolong National Natural Reserve of western Sichuan, China to provide qualitative verification for regional paleoclimatic studies and dynamic vegetation models for carbon uptake.Methods Standardized dendroecological methods were used to study the effects of climatic variability on radial growth of A. faxoniana, a subalpine conifer that was the dominant and economically most important tree species in this region. Fifty-two increment cores of A. faxoniana were sampled in a pristine forest site at 2 750 m and sev-eral statistics were used to identify common patterns of interannual growth variability. A shift in climate facilitated comparison of growth-climate relationships during two distinct periods: 1956–1976 and 1977–2008. Tree radial growth was correlated against monthly total precipitation, sunshine time and mean, minimum, and maximum temperature from the nearby meteorological station.Important findings Tree radial growth showed time-dependent relationships to interannual climate variation. For 1956–1976, tree growth showed a positive growth response to temperature in late winter to early spring (prior December to current April), whereas high temperature in late spring (May) negatively impacted tree growth. For 1977–2008, tree growth responded more strongly to sunshine time (positive) and winter temperature (negative). In addition, tree growth showed an internally consistent positive response to precipitation in autumn to early winter (prior September to December). An anomalous reduction in growth indices was a noteworthy feature in 1977–2008 and resulted in increasing divergence between the trends in ring width and temperature. In recent ——————————————————收稿日期Received: 2010-03-25接受日期Accepted:2010-05-25* 通讯作者Author for correspondence (E-mail: ghliu@)1046 植物生态学报Chinese Journal of Plant Ecology 2010, 34 (9): 1045–1057decades, the combination of decline in sunshine time and more cloud cover effectively decreased the amount of solar radiation available for photosynthesis and plant growth, and this was the most probable cause for the recent progressive decline in growth.Key words climate response, tree-ring, western Sichuan, Wolong National Natural Reserve树木年轮材料在重建过去千年的高分辨率的气候变化历史研究中起着重要作用, 并在区域甚至全球范围的气候变化研究中成为首选的气候代用材料。
树木年轮数据的气候重建序列对于人们了解最近100多年以来气候变化的自然背景和预测未来数十年气候变化前景, 都具有重要的意义(IPCC, 2007; Mann et al ., 2008)。
然而过去十几年来, 越来越多的研究表明, 北半球高纬度地区的树木生长对于气候的响应是不稳定的, 在近代出现了明显的转型, 即树木生长分离效应(divergence problem) (Briffa et al ., 1998)。
树木生长分离效应是指在全球变暖的背景下, 北半球高纬度广大地区对于温度响应敏感的树轮资料, 在20世纪后期对于温度响应明显降低, 即近代树木生长与20世纪全球变暖趋势出现了明显的分离, 使得树木年轮数据在区域尺度上很难拟合20世纪的变暖趋势(D’Arrigo et al ., 2007; Wilson et al ., 2007)。
树木生长分离效应首先是在美国阿拉斯加地区发现的(Jacoby & D’Arrigo, 1995), 随后在世界各地开展了大量的相关研究(Barber et al ., 2000; Solberg et al ., 2002; Wilmking et al ., 2004, 2005; Büntgen et al ., 2006, 2008; Pisaric et al ., 2007; Oberhuber et al ., 2008; Esper & Frank, 2009)。