Study on Carbon Storage Estimation of Cunninghamia lanceolata in Longquan

In February 2022, 2 pure 18-year and 27-year Cunninghamina lanceolata plantations in Longquan city, Zhejiang province were selected for establishment of 9 sample plots each. Determinations were carried out on crown width, DBH and height of each tree in 18 sample plots. The crown width of 378 C. lanceolata trees were extracted by visible light images from Dajiang M300 UAV and accuracy analyzed with the measured one by local transect method. According to the measured crown width, DBH and tree height, the regression models of crown width and DBH and of DBH and tree height were established. The extracted crown width is used to estimate the DBH based on regression model of crown width and DBH, and the DBH estimates are used to estimate the tree height based on regression model of DBH and tree height. The individual tree DBH and tree height estimates are input into the relative growth equation of carbon storage to estimate the carbon storage of individual tree and stand. The result showed that the relationship between DBH and tree height was linear function, and the coefficient of determination (R2) is over 0.89. The relationship between DBH and crown width was linear, and R2 were 0.55 and 0.61 for different plantation. The accuracy of individual tree crown width extracted from UAV images was more than 71.55%, and the accuracy of individual tree DBH and tree height estimates based on extracted crown width were more than 78.24% and 79.80%. Carbon storage estimates of individual tree for 2 plantations ranged from 3.92 kg to 35.49 kg and from 15.07 kg to 53.72 kg, with accuracies of 46% and 54.60%. Carbon storage estimates were 63.98 t/ha and 45.23 t/ha of two plantations.