文献类型：期刊文献

英文题名：Monitoring Spatiotemporal Variation of Individual Tree Biomass Using Multitemporal LiDAR Data

作者：Qi, Zhiyong[1,2,3] Li, Shiming[1,2,3] Pang, Yong[1,2,3] Du, Liming[1,2,3] Zhang, Haoyan[1,2,3] Li, Zengyuan[1,2,3]

第一作者：Qi, Zhiyong

通信作者：Li, SM[1];Li, SM[2];Li, SM[3]

机构：[1]Chinese Acad Forestry, Res Inst Forest Resource Informat Tech, Beijing 100091, Peoples R China;[2]Natl Forestry & Grassland Adm, Key Lab Forestry Remote Sensing & Informat Syst, Beijing 100091, Peoples R China;[3]Natl Forestry & Grassland Sci Data Ctr, Beijing 100091, Peoples R China

年份：2023

卷号：15

期号：19

外文期刊名：REMOTE SENSING

收录：;EI(收录号：20234214913753);Scopus(收录号：2-s2.0-85174167004);WOS:【SCI-EXPANDED(收录号:WOS:001083424700001)】；

基金：This research was funded by the National Key R & D Program of China (Project Number: 2020YFE0200800 and 2022YFD1400405) and National Science and Technology Major Project of China's High Resolution Earth Observation System (Project Number: 21-Y20B01-9001-19/22-1)

语种：英文

外文关键词：aboveground biomass; multitemporal LiDAR; tree level; pulse density; Gini coefficient

摘要：Assessing the spatiotemporal changes in forest aboveground biomass (AGB) provides crucial insights for effective forest carbon stock management, an accurate estimation of forest carbon uptake and release balance, and a deeper understanding of forest dynamics and climate responses. However, existing research in this field often lacks a comprehensive methodology for capturing tree-level AGB dynamics using multitemporal remote sensing techniques. In this study, we quantitatively characterized spatiotemporal variations of tree-level AGB in boreal natural secondary forests in the Greater Khingan Mountains region using multitemporal light detection and ranging (LiDAR) data acquired in 2012, 2016, and 2022. Our methodology emphasized improving the accuracy of individual tree segmentation algorithms by taking advantage of canopy structure heterogeneity. We introduced a novel three-dimensional metric, similar to crown width, integrated with tree height to calculate tree-level AGB. Moreover, we address the challenge of underestimating tree-level metrics resulting from low pulse density, ensuring accurate monitoring of AGB changes for every two acquisitions. The results showed that the LiDAR-based Delta AGB explained 62% to 70% of the variance of field-measured Delta AGB at the tree level. Furthermore, when aggregating the tree-level AGB estimates to the plot level, the results also exhibited robust and reasonable accuracy. We identified the average annual change in tree-level AGB and tree height across the study region, quantifying them at 2.23 kg and 0.25 m, respectively. Furthermore, we highlighted the importance of the Gini coefficient, which represents canopy structure heterogeneity, as a key environmental factor that explains relative AGB change rates at the plot level. Our contribution lies in proposing a comprehensive framework for analyzing tree-level AGB dynamics using multitemporal LiDAR data, paving the way for a nuanced understanding of fine-scale forest dynamics. We argue that LiDAR technology is becoming increasingly valuable in monitoring tree dynamics, enabling the application of high-resolution ecosystem dynamics products to elucidate ecological issues and address environmental challenges.