Canopy gap delineation using UAV data in a Hyrcanian forest (Case study: Shastklateh Forest)

Document Type : Research Paper

Authors

1 Ph.D. Candidate of Forestry, Dept. of Forestry, Faculty of Forest Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, I. R. Iran

2 Prof., Dept. of Forestry, Faculty of Forest Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, I. R. Iran

3 Associate Prof., Dept. of Forestry, Faculty of Forest Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, I. R. Iran.

4 4Associate Prof., Dept. of Silviculture and Forest Ecology, Faculty of Forest Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, I. R. Iran

Abstract

Canopy gap delineation is essential for achieving a better comprehension of forest structure. This study aims to (a) extract canopy gaps using UAV data and (b) compare the performance of different canopy gap extraction methods in a managed stand in the northeast of Iran. A canopy height model (CHM) was produced by subtracting LIDAR digital terrain model from the UAV digital surface model. CHM classification performs to extract gaps by thresholding CHM (fixed height and CHM slope and relative height thresholds) and object-based classification on the UAV CHM and orthophoto. Ground truth is produced in the point and polygon forms through field measurements and visual interpretation of the UAV orthophoto. The geometry of the canopy gaps (Area, perimeter, and shape complexity) was calculated. Finally, the point and polygon base accuracy of delineated gaps assess for each of the methods. Point accuracy assessment suggests that 60% CHM slope produces the highest overall accuracy and Kappa coefficient of 91.7% and 0.874, respectively. About area accuracy assessment, the best match between delineated gaps and ground truth polygons was achieved by using relative height and 60% CHM slope thresholds. The lowest mean errors of GSCI produced by 70% CHM slope (0.15). Moreover, object-based classification showed the lowest mean error of area (33.76 m2) and perimeter (16.80 m). In conclusion, while area accuracy is considered the best fit of the delineated gap's geometry is gained by the object-based classification.

Keywords


 
Amini, Sh., Moayeri, M.H., Shataee Jouibary, Sh., & Rahmani, R. (2021). Geometric indices and regeneration species diversity in natural and man-made canopy gaps. Journal of Wood & Forest Science and Technology, 28(1), 1-20.
Amiri, M., Dargahi, D., Azadfar, D., & Habashi, H. (2009). Comparison structure of the natural and managed Oak (Quercus castaneifolia) stand (shelter wood system) in forest of Loveh, Gorgan. Journal of Agricultural Natural Resour Sciences, 15(6), 1-11.
Bonnet, S., Gaulton, R., Lehaire, F., & Lejeune, P. (2015). Canopy gap mapping from airborne laser scanning: An assessment of the positional and geometrical accuracy. Remote Sensing, 7(9), 11267-11294.
Brokaw, N.V.L., & Scheiner, S.M. (1989). Species composition in gaps and structure of a tropical forest. Ecology, 70(3), 538-541.
Clinton, N., Holt, A., Scarborough, J., Yan, L.I., & Gong, P. (2010). Accuracy assessment measures for object-based image segmentation goodness. Photogrammetric Engineering and Remote Sensing, 76(3), 289-299.
Dam, O. (2001). Forest Filled with Gaps: E_ects of Gap Size on Water and Nutrient Cycling in Tropical Rain Forest: A Study in Guyana: Universiteit Utrecht.
Dupuis, C., Lejeune, P., Michez, A., & Fayolle, A. (2020). How can remote sensing help monitor tropical moist forest degradation?-A systematic review. Remote Sensing, 12(7), 1-24.
Gagnon, J.L., Jokela, E.J., Moser, W.K., & Huber, D.A. (2004). Characteristics of gaps and natural regeneration in mature longleaf pine flatwoods ecosystems. Forest Ecology and Management, 187(2–3), 373–380.
Gaulton, R., & Malthus, T.J. (2010). LiDAR mapping of canopy gaps in continuous cover forests: A comparison of canopy height model and point cloud based techniques. International Journal of Remote Sensing, 31(5), 1193-1211.
Getzin, S., Nuske, R.S., & Wiegand, K. (2014). Using unmanned aerial vehicles (UAV) to quantify spatial gap patterns in forests. Remote Sensing, 6(8), 6988-7004.
González-Ferreiro, E., Diéguez-Aranda, U., Barreiro-Fernández, L., Buján, S., Barbosa, M., Suárez, J.C., Bye, I.J., & Miranda, D. (2013). A mixed pixel- and region-based approach for using airborne laser scanning data for individual tree crown delineation in Pinus radiata D. on plantations. International Journal of Remote Sensing, 34(21), 7671-7690.
Green, P.T. (1996). Canopy gaps in rain forest on Christmas Island, Indian Ocean: Size distribution and methods of measurement. Journal of Tropical Ecology, 12(3), 427–434.
Gu, J., Grybas, H., & Congalton, R.G. (2020). A comparison of forest tree crown delineation from unmanned aerial imagery using canopy height models vs. spectral lightness. Forests, 11(6), 2-15.
Hobi, M. L., Ginzler, C., Commarmot, B., & Bugmann, H. (2015). Gap pattern of the largest primeval beech forest of Europe revealed by remote sensing. Ecosphere, 6(5) 1-15.
Kavzoglu, T., & Tonbul, H. (2017). A comparative study of segmentation quality for multi-resolution segmentation and watershed transform. 8th International Conference on Recent Advances in Space Technologies (RAST), June, 113-117.
Kern, C.C., Montgomery, R.A., Reich, P.B., & Strong, T.F. (2014). Harvest-created canopy gaps increase species and functional trait diversity of the forest ground-layer community. Forest Science, 60(2), 335-344.
Koukoulas, S., & Blackburn, G.A. (2004). Quantifying the spatial properties of forest canopy gaps using LiDAR imagery and GIS. International Journal of Remote Sensing, 25(15), 3049-3072.
Koukoulas, S., & Blackburn, G.A. (2005). Spatial relationships between tree species and gap characteristics in broad‐leaved deciduous woodland. Journal of Vegetation Science, 16(5), 587-596.
Kucbel, S., Jaloviar, P., Saniga, M., Vencurik, J., & Klimaš, V. (2010). Canopy gaps in an old-growth fir-beech forest remnant of Western Carpathians. European Journal of Forest Research, 129(3), 249-259.
Larrinaga, A.R., & Brotons, L. (2019). Greenness indices from a low-cost UAV imagery as tools for monitoring post-fire forest recovery. Drones, 3(1), 1-16.
Lingua, E., Garbarino, M., Mondino, E.B., & Motta, R. (2011). Natural disturbance dynamics in an old-growth forest: From tree to landscape. Procedia Environmental Sciences, 7, 365-370.
Liu, D., & Xia, F. (2010). Assessing object-based classification: Advantages and limitations. Remote Sensing Letters, 1(4), 187-194.
Mao, X., & Hou, J. (2019). Object-based forest gaps classification using airborne LiDAR data. Journal of Forestry Research, 30(2), 617–627.
Mathews, A. J. (2015). A practical UAV remote sensing methodology to generate multispectral orthophotos for vineyards: Estimation of spectral reflectance using compact digital cameras. International Journal of Applied Geospatial Research, 6(4), 65–87.
Mohammadi, J., Shataee, S., Namiranian, M., & Nasset, E. (2017). Modeling biophysical properties of board-leaved stands in the hyrcanian forest of Iran using fused airborne laser scanner data and UltraCam-D images. International journal of applied earth observation geoinformation, 61, 32-45.
Motohka, T., Nasahara, K. N., Oguma, H., & Tsuchida, S. (2010). Applicability of green-red vegetation index for remote sensing of vegetation phenology. Remote Sensing, 2(10), 2369-2387.
Moradi, A., Satari, M., & Momeni, M. (2018). Extracting the individual trees of urban forests from high density airborn LiDAR data. Iranian Journal of Forest, 10(1), 27-42.
Nasiri, V., Darvishsefat, A.A., Arefi, H., & Namiranian, M. (2020). Estimating mean crown diamete using UAV imagery based on multiresolution and watershed segmentation methodes (case study: Kheyrud forest). Iranian Journal of Forest, 12(1), 131-145.
Orman, O., Dobrowolska, D., & Szwagrzyk, J. (2018). Gap regeneration patterns in Carpathian old-growth mixed beech forests – Interactive effects of spruce bark beetle canopy disturbance and deer herbivory. Forest Ecology and Management, 430, 451-459.
Salmani, S., Ebrahimy, H., Mohammadzade, K., & Valizadeh Kamran, K. (2019). Evaluating efficiency of object-based classification techniques used to extract land use from IKONOS satellite imageries. Scientific-Research Quarterly of Geographical Data (Sepehr)28(111), 205-215.
Schliemann, S.A., & Bockheim, J.G. (2011). Methods for studying treefall gaps: A review. Forest Ecology and Management, 261(7), 1143–1151.
Sefidi, K., & Sadeghi, M.M. (2021). Anthropogenic disturbance impacts on spatial pattern of Caucasian Oak (Quercus macrnthera) stands in Hatam Mashe Si forests, Arasbaran. Iranian Journal of Forest, 13(2), 155-168.
Seidel, D., Ammer, C., & Puettmann, K. (2015). Describing forest canopy gaps efficiently, accurately, and objectively: New prospects through the use of terrestrial laser scanning. Agricultural and Forest Meteorology, 213, 23–32.
Vepakomma, U., St-Onge, B., & Kneeshaw, D. (2008). Spatially explicit characterization of boreal forest gap dynamics using multi-temporal lidar data. Remote Sensing of Environment, 112(5), 2326-2340.
White, J.C., Tompalski, P., Coops, N.C., & Wulder, M.A. (2018). Comparison of airborne laser scanning and digital stereo imagery for characterizing forest canopy gaps in coastal temperate rainforests. Remote Sensing of Environment, 208, 1-14.
Xuegang, M., Liang, Z., & Fan, W. (2020). Object-oriented automatic identification of forest gaps using digital orthophoto maps and LiDAR data. Canadian Journal of Remote Sensing, 46(2), 177-192.
Yang, J., Jones, T., Caspersen, J., & He, Y. (2015). Object-based canopy gap segmentation and classification: Quantifying the pros and cons of integrating optical and LiDAR data. Remote Sensing, 7(12), 15917-15932.
Zeybek, M., & Şanlıoğlu, İ. (2019). Point cloud filtering on UAV based point cloud. Measurement. Journal of the International Measurement Confederation, 133, 99-111.
Zhang, K. (2008). Identification of gaps in mangrove forests with airborne LIDAR. Remote Sensing of Environment, 112(5), 2309-2325.
Zielewska-Büttner, K., Adler, P., Ehmann, M., & Braunisch, V. (2016). Automated detection of forest gaps in spruce dominated stands using canopy height models derived from stereo aerial imagery. Remote Sensing, 8(3), 1-21.