联合摄影及斜点样方法的单株植物冠层结构参数测量(Ⅱ)：结构参数测量

ESTIMATING GEOMETRICAL PARAMETERS OF ISOLATED TREES BY UNIFYING PHOTOGRAPHY AND POINT QUADRAT METHODS(Ⅱ):ESTIMATING GEOMETRICAL PARAMETERS

总结了单株冠层叶面积指数(LAI)测量方法发展历史、现状及存在的问题,提出了联合摄影及斜点样方法的单株植物冠层总面积指数(PAI)测量方法.研究发现,选择合理的单位体元大小及分区大小组合方案对单株冠层几何参数及PAI测量十分关键.任意组合单位体元大小及分区大小可引起几何参数及PAI测量异常,当单位体元大小与分区大小之间相互匹配时,冠层几何参数及PAI测量结果稳定性良好.与立体体元大小相比,分区大小对冠层几何参数及PAI测量结果影响更为显著.

The current status and problems for indirect LAI estimation of isolated trees was concluded, and a new method unifying photography and point quadrat methods was proposed. Arbitrary choice for voxel and pixel zone sizes can introduce vital errors, a reasonable and harmonious choice of voxel and pixel zone sizes are critical. With voxel size and pixel zone size reciprocally harmonious, data stability between schemes is ensured. Compared to voxel size, the size of pixel zone is more important.