基于光学仪器法测定谷地云冷杉林叶面积指数的季节变化

Estimation of seasonal changes in leaf area index based on optical methods in spruce-fir valley forest

利用半球摄影法（DHP）和LAI-2000植物冠层分析仪两种光学仪器法（间接法）以及凋落物法（直接法）,研究了小兴安岭谷地云冷杉林叶面积指数（LAI）的季节变化,并构建了不同季节直接法与间接法测定的LAI间的相关关系.结果表明：在整个试验期间,DHP测定的LAI比直接法测定值低估40%~48%,LAI-2000植物冠层分析仪的低估范围为15%~26%;不同时期直接法与DHP和LAI-2000植物冠层分析仪测定的LAI均显著相关,且均可合并为A、B、C 3类预测模型,可以分别预测5和11月,6、9和10月,7和8月的LAI.本研究结果可为高效、准确地测定针叶林LAI的季节变化提供参考.

The seasonal changes in LAI were respectively measured using digital hemispherical pho- tography （DHP） , LAI-2000 plant canopy analyzer （indirect methods） and litter collection method （ direct method） in spruce-fir valley forest in the Xiaoxing＇ an Mountains, China. In addition, we constructed the relationships between LAI from direct method and that from indirect methods in dif- ferent seasons. The results showed that LAI from DHP underestimated LAI from direct method by 40%-48% in the whole study period, and the underestimation range for LAI-2000 plant canopy analyzer was 15%-26%. LAI from direct method and that from DHP or LAI-2000 plant canopy analyzer all correlated significantly in different seasons, and the relationships between LAI from di- rect method and that from DHP or LAI-2000 plant canopy analyzer all could be merged into three classified prediction models after testing, i. e. , A, B and C, which were able to predict LAI in May and November, June, September and October, and July and August, respectively. This study laid a foundation for effective and accurate measurement of seasonal changes in LAI for coniferous forest in subsequent studies.