梁尔源-喜马拉雅山南坡高山树线形成机制探讨.ppt

梁尔源 2015.11.08 1. 林线树木生长对气候变化的响应 3. 尼泊尔桦树林线野外调查 * 喜马拉雅山南坡高山树线形成机制探讨 气候因子是限制林线过度带内树木生理和种群动态的主要限制因子 (Malanson 2001; K?rner 2003; Holtmeier and Broll 2005; Nagy and Grabherr 2009). 基于全球尺度上林线不同温度参数的相似性 (Jobbágy and Jackson 2000; Grace et al. 2002; K?rner and Paulsen 2004), 生长限制假说 （the growth limitation hypothesis）得到广泛认可：生长季温度是高纬度和高海拔林线上树木生长的主要限制因子 (e.g., K?rner 2003; K?rner and Paulsen 2004; Wieser and Tausz 2007). 生长限制假说得到全球尺度上一系列林线树轮研究 (e.g., Payette et al. 1989; M?kinen et al. 2000; Tardif et al. 2003; Frank and Esper 2005; Luckman and Wilson 2005; Villalba et al. 1997; Vila et al. 2008; Liang et al. 2009; Salzer et al. 2009; Huang et al. 2010; Ettinger et al. 2011), 形成层活动 (Rossi et al., 2008) 和机理模型的 (Dullinger et al. 2004; Wiegand et al. 2006)支持. 过去200年来树线的位置没有发生显著的变化，但种群密度呈持续增加的趋势。变暖向更有利于树线过渡带内的冷杉更新。 Liang et al., 2011, New Phytologist Little ice age Maximum 监测 Xu et al., 2012, Science in China Ser D 青藏高原高山林线上树木的生长受温度限制，支持生长受限假说。 气候变暖已经造成林线上树木生长的增加 喜马拉雅山南坡高山林线上树木生长动态？ 2. 喜马拉雅山南坡气候概括 采样点海拔：3000米左右，在最大降雨带内 树木的生长受生长季早期温度变化的影响 越高海拔处树木的生长越有可能受降水限制 Liang et al., 2014 Based on the fact that precipitation in the Himalayas decreases with increasing elevation above 2000–3000 m asl, we hypothesized that tree growth at upper timberlines might be more strongly limited by poor moisture availability than by low temperature. Sampling area 2011: west Nepal 2010: Langtang Valley 2011,2012： Manasulu ？ 2013 2012 2010 2011 糙皮桦（Betula utilis D. Don） 模式标本：采自尼泊尔 分布广泛：是喜马拉雅山南坡主要林线树种之一 2014 2014 Liang et al., 2014, Ecology Langtang valley Scale bars in A and B are 2 mm, and in C are 0.2 mm. one row of terminal axial parenchyma cells, often filled with brownish extractives Liang et al., 2014 降水 温度 原因之一 原因之二 Percentage of (A) trees with locally missing rings in 2004 in different age classes, The occurrence of locally missing rings was significantly associated with warm and dry conditions during the pre-monsoon season. Trees at the upper timberline is very thirsty under warm and