中文摘要：

作为表征植被冠层结构的核心参数之一,叶面积指数（LAI）控制着植被冠层的多种生物物理和生理过程,如光合、呼吸、蒸腾、碳循环、降水截获、能量交换等.本文首先阐述了森林冠层地面LAI光学测量方法的理论基础和数学模型;其后介绍了目前主流光学测量方法的测量原理及其优缺点;归纳了LAI光学测量方法的主要误差来源（聚集效应、非光合作用组分、观测条件和地形效应）,并分析总结了聚集效应、非光合作用组分和地形效应的定量评估现状;最后展望了森林冠层地面LAI光学测量方法的未来发展方向.

英文摘要：

Leaf area index（LAI） is an important parameter of canopy structure,because it relates to many biophysical and physiological processes of canopy,including photosynthesis,respiration,transpiration,carbon cycling,precipitation interception,and energy exchange,etc.This paper introduced the theoretical bases and mathematical models of optical methods for forest canopy LAI determination,introduced the principles,merits,and drawbacks of currently used optical methods,and summed up the main sources of the errors in LAI optical measurement,including clumping effect,non-photosynthesis components,measurement conditions,and terrain effect.The developing status of quantitatively evaluating clumping effect,non-photosynthesis components,and terrain effect was analyzed,and the promising development directions of optical methods for measuring forest canopy LAI were discussed.