Leaf area index (LAI) is a key parameter for studying global terrestrial ecology and environment and has great ecological significance. How to accurately measure and calculate structural parameters of trees has become an urgent matter. This paper reports the use of terrestrial laser scanning (TLS) as a measurement tool to achieve accurate LAI estimation through point cloud preprocessing measures, the LeWos algorithm, and voxel methods. The accuracy and feasibility of this indirect measurement method were explored. It is found that the single wood structure parameters extracted from TLS have a good linear relationship with manual measurement, and the extraction errors meet the requirements of real-scene conversion. The study also found when the voxel size is consistent with the minimum distance of the point cloud set by TLS instrument, it has a strong correlation with the measured value of canopy analyser. These results lay the foundation for conveniently and quickly obtaining structural parameters of trees, tree growth state detection, and canopy ecological benefit assessment.
KeywordsLeaf Area IndexTerrestrial Laser ScanningBranch-Leaf SeparationPoint Cloud Voxelization
Niinemets, U., Keenan, T.F. and Hallik, L. (2015) A Worldwide Analysis of Within-Canopy Variations in Leaf Structural, Chemical and Physiological Traits across Plant Functional Types. New Phytologist, 205, 973-993. https://doi.org/10.1111/nph.13096
Majasalmi, T. and Rautiainen, M. (2020) The Impact of Tree Canopy Structure on Understory Variation in a Boreal Forest. Forest Ecology and Management, 466, Article ID: 118100. https://doi.org/10.1016/j.foreco.2020.118100
Gough, C.M., Atkins, J.W., Fahey, R.T. and Hardiman, B.S. (2019) High Rates of Primary Production in Structurally Complex Forests. Ecology, 100, e02864. https://doi.org/10.1002/ecy.2864
Ehbrecht, M., Schall, P., Ammer, C., Fischer, M. and Seidel, D. (2019) Effects of Structural Heterogeneity on the Diurnal Temperature Range in Temperate Forest Ecosystems. Forest Ecology and Management, 432, 860-867. https://doi.org/10.1016/j.foreco.2018.10.008
Xu, J., Quackenbush, L.J., Volk, T.A. and Im, J. (2020) Forest and Crop Leaf Area Index Estimation Using Remote Sensing: Research Trends and Future Directions. Remote Sensing, 12, Article No. 2934. https://doi.org/10.3390/rs12182934
Breda, N.J.J. (2003) Ground-Based Measurements of Leaf Area Index: A Review of Methods, Instruments and Current Controversies. Journal of Experimental Botany, 54, 2403-2417. https://doi.org/10.1093/jxb/erg263
Chen, J.-M. and Black, T.A. (1992) Defining Leaf Area Index for Non-Flat Leaves. Plant, Cell and Environment, 15, 421-429. https://doi.org/10.1111/j.1365-3040.1992.tb00992.x
Macfarlane, C., Hoffman, M., Eamus, D., Kerp, N., Higginson, S., McMurtrie, R. and Adams, M. (2007) Estimation of Leaf Area Index in Eucalypt Forest Using Digital Photography. Agricultural and Forest Meteorology, 143, 176-188. https://doi.org/10.1016/j.agrformet.2006.10.013
Wei, S.-S., Yin, T.-G., Dissegna, M.A., Whittle, A.J., Ow, G.L.F., et al. (2020) An Assessment Study of Three Indirect Methods for Estimating Leaf Area Density and Leaf Area Index of Individual Trees. Agricultural and Forest Meteorology, 292, Article ID: 108101. https://doi.org/10.1016/j.agrformet.2020.108101
Tan, C.-W., Zhang, P.-P., Zhou, X.-X., et al. (2020) Quantitative Monitoring of Leaf Area Index in Wheat of Different Plant Types by Integrating NDVI and Beer-Lambert Law. Scientific Reports, 10, Article No. 929. https://doi.org/10.1038/s41598-020-57750-z
Brown, L.A., Ogutu, B.O. and Dash, J. (2020) Tracking Forest Biophysical Properties with Automated Digital Repeat Photography: A Fisheye Perspective Using Digital Hemispherical Photography from below the Canopy. Agricultural and Forest Meteorology, 287, Article ID: 107944. https://doi.org/10.1016/j.agrformet.2020.107944
Qu, Y.-H., Wang, Z.-X., Shang, J.-L., Liu, J.-G. and Zou, J. (2021) Estimation of Leaf Area Index Using Inclined Smartphone Camera. Computers and Electronics in Agriculture, 191, Article ID: 106514. https://doi.org/10.1016/j.compag.2021.106514
Jonckheere, I., Fleck, S., Nackaerts, K., et al. (2004) Review of Methods for in Situ Leaf Area Index Determination—Part I. Theories, Sensors and Hemispherical Photography. Agricultural and Forest Meteorology, 121, 19-35. https://doi.org/10.1016/j.agrformet.2003.08.027
Yan, G.-J., Hu, R.-H., Luo, J.-H., et al. (2019) Review of Indirect Optical Measurements of Leaf Area Index: Recent Advances, Challenges, and Perspectives. Agricultural and Forest Meteorology, 265, 390-411. https://doi.org/10.1016/j.agrformet.2018.11.033
Srinet, R., Nandy, S. and Patel, N.R. (2019) Estimating Leaf Area Index and Light Extinction Coefficient Using Random Forest Regression Algorithm in a Tropical Moist Deciduous Forest, India. Ecological Informatics, 52, 94-102. https://doi.org/10.1016/j.ecoinf.2019.05.008
Liu, J., Skidmore, A.K., Wang, T.-J., et al. (2019) Variation of Leaf Angle Distribution Quantified by Terrestrial LiDAR in Natural European Beech Forest. ISPRS Journal of Photogrammetry and Remote Sensing, 148, 208-220. https://doi.org/10.1016/j.isprsjprs.2019.01.005
Wang, Y. and Fang, H.-L. (2020) Estimation of LAI with the LiDAR Technology: A Review. Remote Sensing, 12, Article No. 3457. https://doi.org/10.3390/rs12203457
Wulder, M.A., White, J.C., Nelson, R.F., et al. (2012) Lidar Sampling for Large-Area Forest Characterization: A Review. Remote Sensing of Environment, 121, 196-209. https://doi.org/10.1016/j.rse.2012.02.001
Camarretta, N., Harrison, P.A., Bailey, T., et al. (2020) Monitoring Forest Structure to Guide Adaptive Management of Forest Restoration: A Review of Remote Sensing Approaches. New Forests, 51, 573-596. https://doi.org/10.1007/s11056-019-09754-5
Sumnall, M.J., Albaugh, T.J., Carter, D.R., et al. (2022) Effect of Varied Unmanned Aerial vehicle Laser Scanning Pulse Density on Accurately Quantifying Forest Structure. International Journal of Remote Sensing, 43, 721-750. https://doi.org/10.1080/01431161.2021.2023229
Vincent, G., Antin, C., Laurans, M., et al. (2017) Mapping Plant Area Index of Tropical Evergreen Forest by Airborne Laser Scanning. A Cross-Validation Study Using LAI2200 Optical Sensor. Remote Sensing of Environment, 198, 254-266. https://doi.org/10.1016/j.rse.2017.05.034
Korhonen, L., et al. (2017) Comparison of Sentinel-2 and Landsat 8 in the Estimation of Boreal Forest Canopy Cover and Leaf Area Index. Remote Sensing of Environment, 195, 259-274. https://doi.org/10.1016/j.rse.2017.03.021
Calders, K., Adams, J., Armston, J., et al. (2020) Terrestrial Laser Scanning in Forest Ecology: Expanding the Horizon. Remote Sensing of Environment, 251, Article ID: 112102. https://doi.org/10.1016/j.rse.2020.112102
Zheng, G., Moskal, L.M. and Kim, S.H. (2013) Retrieval of Effective Leaf Area Index in Heterogeneous Forests with Terrestrial Laser Scanning. IEEE Transactions on Geoscience and Remote Sensing, 51, 777-786. https://doi.org/10.1109/TGRS.2012.2205003
Hosoi, F. and Omasa, K. (2006) Voxel-Based 3-D Modeling of Individual Trees for Estimating Leaf Area Density Using High-Resolution Portable Scanning Lidar. IEEE Transactions on Geoscience and Remote Sensing, 44, 3610-3618. https://doi.org/10.1109/TGRS.2006.881743
Olsoy, P.J., Glenn, N.F., Clark, P.E. and Derryberry, D.R. (2014) Aboveground Total and Green Biomass of Dryland Shrub Derived from Terrestrial Laser Scanning. ISPRS Journal of Photogrammetry and Remote Sensing, 88, 166-173. https://doi.org/10.1016/j.isprsjprs.2013.12.006
Li, W., Niu, Z., Huang, N., et al. (2015) Airborne LiDAR Technique for Estimating Biomass Components of Maize: A Case Study in Zhangye City, Northwest China. Ecological Indicators, 57, 486-496. https://doi.org/10.1016/j.ecolind.2015.04.016
Gressin, A., Mallet, C., Demantke, J. and David, N. (2013) Towards 3D Lidar Point Cloud Registration Improvement Using Optimal Neighborhood Knowledge. ISPRS Journal of Photogrammetry and Remote Sensing, 79, 240-251. https://doi.org/10.1016/j.isprsjprs.2013.02.019
Li, Y.-Y., Wang, J., Li, B., Sun, W.-X. and Li, Y.-Y. (2021) An Adaptive Filtering Algorithm of Multilevel Resolution Point Cloud. Survey Review, 53, 300-311. https://doi.org/10.1080/00396265.2020.1755163
Pingel, T.J., Clarke, K.C. and McBride, W.A. (2013) An Improved Simple Morphological Filter for the Terrain Classification of Airborne LIDAR Data. ISPRS Journal of Photogrammetry and Remote Sensing, 77, 21-30. https://doi.org/10.1016/j.isprsjprs.2012.12.002
Chen, J.M. and Black, T.A. (1991) Measuring Leaf Area Index of Plant Canopies with Branch Architecture. Agricultural and Forest Meteorology, 57, 1-12. https://doi.org/10.1016/0168-1923(91)90074-Z
Chen, J.-M. (1996) Optically-Based Methods for Measuring Seasonal Variation of Leaf Area Index in Boreal Conifer Stands. Agricultural and Forest Meteorology, 29, 135-163. https://doi.org/10.4095/218392
Wang, D., Takoudjou, S.M. and Casella, E. (2020) LeWoS: A Universal Leaf-Wood Classification Method to Facilitate the 3D Modelling of Large Tropical Trees Using Terrestrial LiDAR. Methods in Ecology and Evolution, 11, 376-389. https://doi.org/10.1111/2041-210X.13342
Li, S.-H., Dai, L.-Y., Wang, H.-S., et al. (2017) Estimating Leaf Area Density of Individual Trees Using the Point Cloud Segmentation of Terrestrial LiDAR Data and a Voxel-Based Model. Remote Sensing, 9, Article No. 1202. https://doi.org/10.3390/rs9111202
Li, Y.-M., Guo, Q.-H., Tao, S.-L., et al. (2016) Derivation, Validation, and Sensitivity Analysis of Terrestrial Laser Scanning-Based Leaf Area Index. Canadian Journal of Remote Sensing, 42, 719-729. https://doi.org/10.1080/07038992.2016.1220829
Taheriazad, L., Moghadas, H. and Sanchez-Azofeifa, A. (2019) Calculation of Leaf Area Index in a Canadian Boreal Forest Using Adaptive Voxelization and Terrestrial LiDAR. International Journal of Applied Earth Observation and Geoinformation, 83, Article ID: 101923. https://doi.org/10.1016/j.jag.2019.101923
Wang, D., Brunner, J., Ma, Z.-Y., et al. (2018) Separating Tree Photosynthetic and Non-Photosynthetic Components from Point Cloud Data Using Dynamic Segment Merging. Forests, 9, Article No. 252. https://doi.org/10.3390/f9050252
Zhu, X., Liu, J., Skidmore, A.K., et al. (2020) A Voxel Matching Method for Effective Leaf Area Index Estimation in Temperate Deciduous Forests from Leaf-On and Leaf-Off Airborne LiDAR Data. Remote Sensing of Environment, 240, Article ID: 111696. https://doi.org/10.1016/j.rse.2020.111696
Parker, G.G. (2020) Tamm Review: Leaf Area Index (LAI) Is both a Determinant and a Consequence of Important Processes in Vegetation Canopies. Forest Ecology and Management, 477, Article ID: 118496. https://doi.org/10.1016/j.foreco.2020.118496