[3] [3] SIMONSON W D, ALLEN H D, COOMES D A. Remotely sensed indicators of forest conservation status: Case study from a Natura 2000 site in southern Portugal[J]. Ecological Indicators, 2013, 24: 636-647.

[4] [4] CHEN S W, NIAN Y Y, HE Z Y, et al. Measuring the tree height of picea crassifolia in alpine mountain forests in Northwest China based on UAV-LiDAR[J]. Forests, 2022, 13(8): 1163.

[5] [5] ZHOU X C, WANG W J, DI L P, et al. Estimation of tree height by combining low density airborne LiDAR data and images using the 3D tree model: A case study in a subtropical forest in China[J]. Forests, 2020, 11(12): 1252.

[7] [7] ROSETTE J A B, NORTH P R J, SUREZ J C. Vegetation height estimates for a mixed temperate forest using satellite laser altimetry[J]. International Journal of Remote Sensing, 2008, 29(5): 1475-1493.

[8] [8] LEFSKY M A, HARDING D J, KELLER M, et al. Estimates of forest canopy height and aboveground biomass using ICESat[J]. 2005, 32(22): L22S02.

[11] [11] LIU X Q, SU Y J, HU T Y, et al. Neural network guided interpolation for mapping canopy height of China′s forests by integrating GEDI and ICESat-2 data[J]. Remote Sensing of Environment, 2022, 269: 112844.

[13] [13] ZHANG W M, QI J B, WAN P, et al. An easy-to-use airborne LiDAR data filtering method based on cloth simulation[J]. Remote Sensing, 2016, 8(6): 501.

[14] [14] KANKARE V, PUTTONEN E, HOLOPAINEN M, et al. The effect of TLS point cloud sampling on tree detection and diameter measurement accuracy[J]. Remote Sensing Letters, 2016, 7(5): 495-502.

[16] [16] CAMPELLO R J G B, MOULAVI D, SANDER J. Density-based clustering based on hierarchical density estimates［C］//PEI J, TSENG VS, CAO L, et al. Pacific-asia conference on knowledge discovery and data mining. Berlin, Heidelberg: Springer, 2013: 160-172.