Accurate measurements of tree height and diameter at breast height (DBH) in forests to evaluate the growth rate of cultivars is still a significant challenge, even when using LiDAR and 3-D modeling. We propose an integrated pipeline methodology to measure the biomass of different tree cultivars in plantation forests with high crown density which that combines unmanned aerial vehicles (UAVs), hyperspectral image sensors, and data processing algorithms using machine learning. Using a planation of Cunninghamia lanceolate, commonly known as Chinese fir, in Fujian, China, images were collected using a hyperspectral camera and orthorectified in HiSpectral Stitcher. Vegetation indices and modeling were processed in Python using decision trees, random forests, support vector machine, and eXtreme Gradient Boosting (XGBoost) third-party libraries. Tree height and DBH of 2880 samples were measured manually and clustering into three groups: “fast growth,” “median,” growth and “normal” growth group, and 19 vegetation indices from 12,000 pixels were abstracted as the input of features for the modeling. After modeling and cross-validation, the classifier generated by random forests had the best prediction accuracy compare to other algorisms (75%). This framework can be applied to other tree species to make management and business decisions.

This research investigated the growth performance and understory dynamics of Chinese fir (Cunninghamia lanceolata) in two ecological plantations 10 km apart in Guangdong Province, China. One ecological plantation was a monoculture comprised solely of Chinese fir. In contrast, the other ecological plantation featured a mix of 30% Chinese fir and 22 other species, encompassing three exotic, five shade-tolerant, six shade-intolerant, and eleven neutral species. Both ecological plantations utilized 1-year-old seedlings planted at 2m × 2m spacing. After 16 years, soil analysis revealed no disparities between the two ecological plantations in total nitrogen, phosphorus, potassium, or pH. Chinese fir in the mixed ecological plantation displayed superior growth, with a 13% increase in diameter, an 18% increase in height, and a 33% increase in crown width compared to those in the monoculture. The leaf area index was higher, and canopy openness was lower in the mixed ecological plantation, indicating an improved canopy structure. Competition indices indicated reduced competition for diameter and increased competition for crown width in the mixed ecological plantation, with no significant difference in competition for height. The monoculture ecological plantation showed higher understory shrub diversity and richness, but no differences were observed in herb diversity and richness between the two ecological plantations. These findings underscore the advantages of mixed-species ecological plantation in enhancing the growth performance of Chinese fir while demonstrating differing effects on shrub and herbaceous understory layers.