广西桉树人工林叶面积指数的估测及其校正  

Leaf area index estimation and correction of Eucalyptus plantation in Guangxi Autonomous Region

作　　者：谢贤胜 卢峰 杨元征 罗蔚生 徐占勇 苏宏新 XIE Xiansheng;LU Feng;YANG Yuanzheng;LUO Weisheng;XU Zhanyong;SU Hongxin(Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation,Nanning Normal University,Nanning 530001,China;State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,China;Guangxi the Forest Resources and Environment Monitoring Center,Nanning 530028,China)

机构地区：[1]广西地表过程与智能模拟重点实验室(南宁师范大学),南宁530001 [2]中国科学院植物研究所植被与环境变化国家重点实验室,北京100093 [3]广西壮族自治区森林资源与生态环境监测中心,南宁530028

出　　处：《生态学报》2022年第11期4451-4462,共12页Acta Ecologica Sinica

基　　金：国家重点研发计划课题(2016YFC0500103,2017YFD0600901⁃4)。

摘　　要：叶面积指数(Leaf area index,LAI)是森林生态系统重要的结构参数,通过遥感技术可反演区域LAI,但其可靠性需要地面准确的实测数据进行验证。选取广西国有高峰林场不同林龄的桉树(Eucalyptus robusta)人工林为对象,以异速生长法(Allometry)为对照,综合利用植物冠层分析仪法(LAI⁃2200)、跟踪辐射和冠层结构分析仪法(TRAC)、半球摄影法(DHP)以及地基激光雷达法(TLS)等间接法估测样地的LAI,并考虑木质成分以及聚集效应影响,进行相应的校正处理,为地面快速、准确测量桉树人工林LAI提供参考。结果表明:桉树人工林的比叶面积为125.37±13.38 cm^(2)/g,通过Allometry获得的LAI变化范围在1.65-3.84,平均为2.73,不同林龄间的差异均显著(P<0.05),随着林龄的增加呈现先增加后减少的趋势。在未校正情况下,LAI⁃2200、TRAC、DHP、TLS估算的LAI存在显著差异(P<0.05)。与对照相比,LAI⁃2200在幼龄林和过熟林中估算误差最小,TRAC在成熟林中估算误差最小。相对于完全去除法,利用PS仿制法校正桉树人工林的木质部影响更为合理,木质比例在0.33%-25.95%,聚集指数在0.63-1.00,两者对间接法估测LAI的影响程度相当。Leaf area index(LAI)is an important structural parameter of forest ecosystem,and the regional LAI can be retrieved through remote sensing technology.However,due to the complexity of forest structure and the heterogeneity of ground features,its reliability needs to be verified by accurately measured data on the ground.Using Eucalyptus plantation of different ages in the Guangxi State-owned Gaofeng Forest Farm as the object and the Allometry method as the control,this study uses indirect methods such as LAI⁃2200 plant canopy analyzer(LAI⁃2200),tracing radiation and architecture of canopies(TRAC),digital hemispherical photography(DHP),and terrestrial laser scanning(TLS)to estimate the LAI of the sample plots.The study also takes into account the influence of wood elements and clumping effect to conduct corresponding correction treatment,which provides a reference for the quick and accurate measurement of the LAI of Eucalyptus plantation on the ground.The results showed that the specific leaf area of Eucalyptus plantation was 125.37±13.38 cm^(2)/g,and the LAI obtained by the Allometry method ranged from 1.65 to 3.84,with an average of 2.73.The differences between different forest ages were significant(P<0.05),showing a trend of first increasing and then decreasing as the forest age increased.Without correction,there were significant differences in the LAI estimated by LAI⁃2200,TRAC,DHP,and TLS(P<0.05).Compared with the control,LAI⁃2200 had the smallest estimation error in young and over⁃mature forests,and TRAC had the smallest estimation error in mature forests.LAI was generally underestimated by different indirect methods.Without considering the correction,the LAI⁃2200 is the most suitable choice,which can obtain accurate LAI.It is necessary to further consider automatic exposure problems during measurement of LAI by DHP.For TLS,it is necessary to further consider the inversion model according to the forest stand environment and use airborne laser scanning(ALS)to appropriately supplement the point cloud

关 键 词：有效叶面积指数 真实叶面积指数 桉树人工林 传统光学仪器 地基激光雷达 

分 类 号：S792.39[农业科学—林木遗传育种]