基于三维激光点云的城市绿化树种材积及树干碳储量无损精确测算

城市森林是森林碳库的重要组成部分。为探索三维激光扫描技术（TLS）在无损精确测算城市绿化树种树干材积及碳储量方面的潜力，了解不同区分段长度对基于TLS测算树干材积的影响并对现有模型测算的树干材积及碳储量的精度进行了评估，采集30株无患子Sapindus mukorossi点云，并按径阶采集树干钻芯样本，研究在不同区分段长度下测算的树干材积及碳储量，并与现有模型的测算结果相比较。结果表明:①基于TLS能够提取高精度的立木胸径和树高（平均相对误差分别为1.97%和4.85%），可实现城市绿化树种树干材积及碳储量的无损精确测算。②基于TLS在区分段长度小于0.50 m时能测算得到高精度的树干材积。③城市绿化树种的材积和树干碳储量与野外林分存在显著差异（P < 0.05）。现有模型并不适用于城市绿化树种。

Nondestructive and accurate measurement of volume and stem carbon storage for urban greening tree species based on terrestrial laser scanning point cloud

Nondestructive and accurate measurement of stem volume and carbon storage for urban green tree species play an important role in forest carbon stock. To explore terrestrial laser scanning (TLS) potential, to determine the effect of different section lengths on measurement precision, and to evaluate the accuracy of the existing models, 30 point cloud samples of Sapindus mukorossi were collected by TLS, and the stem drill cores were also sampled according to the diameter grade by CO250 to obtain stem volume and carbon storage data using different section lengths. Afterward these were compared with data derived from existing models. Results showed that. (1) The diameter at breast height (DBH) and tree height could be measured with high accuracy based on TLS with a mean relative error for DBH of 1.97% and for height of 4.85%. (2) Based on TLS, when the section length was less than 0.50 m, stem volume could be measured accurately. (3) The existing models (including one-way volume model and standard volume model and stem carbon storage model) are not suitable for the stem volume and carbon storage of urban greening tree species, as the result of one-way ANOVA are significant (P < 0.05). Therefore, TLS is reliable in the field of nondestructive and accurate measurement of stem volume and carbon storage for urban greening tree species.