Since its reformation the Chinese economy has developed at a rapid pace, similar progress can be seen in the country’s forestry industry. Unfortunately, such progress has led to a severe reduction in forest resources and degradation of the associated environments. To combat this, sustainable development strategies have been introduced with ecological conservation and management an important element. A key to strategy is the undertaking of a forestry census.
The conventional approach to a forest census is to use ground observation and aerial photogrammetry to determine species types, distributions, growth status, canopy areas, timber volume, and pests and diseases types and distributions. This information is critical for accurate decision support for the optimal management of the forestry resources.
The use of LiDAR technologies in conjunction with imagery provides a much richer picture of a forest’s structure. The key features of LiDAR are its ability to penetrate the forest canopy and to receive multiple echoes from the sub-canopy vegetation. When combined with simultaneously acquired multi-spectral imagery and other environmental sensor data, a complete census of a forest is produced.
Forest mapping is the major component of a forestry census as it forms the framework for the necessary spatial analysis. As for all surveys, there are two processes: data acquisition and data processing. Data acquisition includes the LiDAR system data (LASER echoes and navigation information) and additional imagery and sensor data. Then the data is processed to produce a rendered 3D point cloud from which 3D models and maps of the forest, analysis of crown widths, growth density, timber volumes and growth trends, and forest health reports may be extracted.