金露梅灌丛是祁连山最具代表性的高寒落叶灌丛,其生长过程对生态系统服务功能有重要影响。2015年生长季对其叶功能性状进行了观测,并利用地物光谱仪(ASD)对金露梅灌丛不同物候期的高光谱反射率进行了测定。结果表明:金露梅灌丛的叶面积、叶面积指数(leaf area index,LAI)、绿色叶面积指数、叶片叶绿素含量(以SPAD值表示)从生长初期开始呈现先增大,到生长后期开始下降的规律;不同物候期金露梅灌丛的反射光谱波形曲线变化规律基本相似;植被指数NDVI、EVI、CIred edge与LAI、叶片SPAD值均达到了显著(P〈0.05)或极显著相关(P〈0.001);EVI与LAI的相关性最好,NDVI与叶片SPAD值的相关性在整个生长阶段最为稳定。根据相关性分析,建立了不同物候期金露梅灌丛LAI、SPAD预测模型,为金露梅植被生长过程的遥感监测提供了方法。
Potentilla froticosa is a most representative alpine deciduous shrub in Qilian Mountains. The growing process of the shrub plays an important role in ecosystem services. In the growing season of 2015,we observed leaf traits of P. froticosa and measured its hyperspectral reflectance by ASD in different phenological phases. The results showed that leaf area,leaf area index( LAI),green leaf area index,chlorophyll content( SPAD values) increased from the beginning of the growing season,reaching their peak in the first half of August,and then declined in the end of the growing season. The change trends of reflection spectrum waveform curve of P. fruticosa shrub in different phenological phases were similar. The correlations between the vegetation indexes( NDVI,EVI,and CIred edge) and LAI,leaf SPAD value were significant( P〈0.05) or extremely significant( P〈0.001). The relationship between EVI and LAI was the best,and the relationship between NDVI and leaf SPAD value was the most stable. According to the regression analysis,statistic models were built to estimate the LAI and leaf SPAD value considering vegetation indexes in different phenological phases. It is concluded that the LAI and leaf SPAD value can be indicators of plant growth state,and we can monitor the growing process of P. froticosa by the EVI and NDVI derived from remote sensing data at regional scale.