穿透雨减少下锐齿栎叶片光合色素季节动态及其反射光谱响应

Leaf photosynthetic pigment seasonal dynamic of Quercus aliena var. acuteserrata and its spectral reflectance response under throughfall elimination

通过林地穿透雨排除的方法模拟降雨减少,测定河南宝天曼自然保护区锐齿栎叶片光合色素含量与反射光谱的季节变化,对减雨处理造成的光合色素变化及其反射光谱的变化进行了定量分析,并探讨了水分控制条件下反射光谱对叶片光合色素变化的响应机制.结果表明:锐齿栎叶片的光合色素含量和色素比率均呈现明显的季节变化.减雨样地与对照样地叶片的光合色素含量和比率在生长季的各个时期存在差异,其中,叶片叶绿素b(Chl b)含量的差异显著,说明Chl b对减雨处理的敏感性最高,叶片类胡萝卜素(Car)含量的差异较小,说明Car对减雨处理的敏感性相对较弱.550 nm处的光谱反射率对色素季节变化的响应最敏感,以其构造的简单比值指数(SR_(750,550))与叶片Chl a、Chl b、总Chl和Car含量的正相关关系显著,光化学反射指数(PRI)与叶片Car/Chl的负相关关系显著.550 nm处的光谱反射率对减雨处理造成的色素变化响应最为敏感.SR_(750,550)对减雨处理造成的叶片Chl a、Chl b和总Chl的含量变化表现敏感(P<0.01),对Chl a/b的变化不敏感.PRI对减雨处理造成的叶片Car/Chl变化表现敏感(P<0.01).

Our objective was to explore the mechanism of spectral reflectance response to leaf photosynthetic pigment seasonal dynamic of Quercus aliena var. acuteserrata under throughfall elimination. We simulated rainfall decline through throughfall elimination （TFE） treatment in the experiment plots of Baotianman Natural Reserve in Henan, measured leaf pigment content and its spectral reflectance during growing season in both TFE and control plots. We analyzed seasonal changes of photosynthetic pigments and changes of pigments induced by TFE and their spectral reflectance responses. The results showed that all photosynthetic pigments content and pigment-ratios exhibited clear seasonal patterns, Leaf photosynthetic pigments content and ratio had differences between TFE plot and control plot during the whole growing season, and significant difference was found in chlorophyll b （Chl b） indicating that Chl b had higher sensitivity than other pigments. Carotenoids （Car） content showed minor difference compared with other pigments, indicating that Car had less sensitivity to TFE. The spectral reflectance of 550 nm was found to be the waveband most sensitive to seasonal changes of pigments, so we formulated the sample ratio index （SR750,550） based on it. The strong positive relationships between SR750,550 and Chl a, Chl b, Chl and Car contents were found with high significant level. Similarly, significant negative relationships were also been found between photochemical reflectance index （PRI） and Car/Chl. The spectral reflectance of 550 nm was most sensitive to changes of pigments induced by TFE. SR750,550 was sensitive to changes of leaf Chl a, Chl b and Chl content induced by TFE （P〈0.01） , but not to change of Chl a/b. PRI was sensitive to change of leaf Car/Chl induced by TFE （P〈0.01）.