杜鹃叶片气孔长度和密度对海拔变化的响应

利用光学显微镜，研究陇西黄土高原兴隆山自然保护区2 600～3 100 m海拔带内高山杜鹃（Rhododendron lapponicum）和烈香杜鹃（Rhododendron anthopogonoides)（高山杜鹃分布在北坡，烈香杜鹃分布在南坡）叶片气孔长度和密度随海拔高度的变化情况，并通过建立大气温度、大气CO₂浓度等环境因子与海拔高度之间的变化关系，探讨了杜鹃叶片气孔长度和密度随海拔高度升高而发生变化的原因。结果表明：海拔高度由低到高，高山杜鹃叶片气孔长度有减小趋势，气孔密度有显著增加趋势；烈香杜鹃叶片气孔长度随海拔高度升高先增大后减小，气孔密度先减小后增大。海拔高度的变化能够引起大气温度、大气CO₂浓度和地势等的变化。高山杜鹃通过增加叶片气孔长度并减小叶片气孔密度来适应环境温度和CO₂浓度的变化，烈香杜鹃则通过增加叶片气孔长度，并减小叶片气孔密度达到对环境温度、CO₂浓度和土壤湿度的最大适合度。

Variation of Stomatal Length and Stomatal Density in Leaves of Rhododendronswith Elevation

This paper investigated the stomatal length (SL) and stomatal density (SD) of Rhododendron lapponicum and R. anthopogonoides collected from different altitudes ranging from 2 600 to 3 100 m in Xinglong Mountains. The factors affecting the variations of SL and SD at different altitudes were also analyzed using the data of air temperature, CO2 concentration and terrain. The results showed that SL was decreased but SD increased significantly in leaves of R. lapponicum with the increase of altitude. SL in leaves of R. anthopogonoides was increased at first and then decreased, and SD was opposite. Air temperature and CO₂ concentration were strongly affected by altitude. R. lapponicum acclimatizes mainly the change of temperature and CO₂ concentration by increasing SL and decreasing SD in its leaves, while R. anthopogonoides acclimatizes mainly the change of air temperature, CO₂ concentration and soil moisture content by increasing SL and decreasing SD in its leave.