ObjectiveDiameter at breast height (DBH), also called tree stem diameter, is one of many critical tree descriptors. Studying on the portable, fast and accurate tree diameter method for forestry application becomes the research focus. To solve these problems of low efficiency and low degree of digital in traditional measurement method and high cost, poor portability, difficult expansion data analysis in recent years of new products, we need to develop a portable system for measuring DBH, which has advantages of low cost, high precision, simple operation, short time consuming and functions of measurement, data upload, query, management, statistics analysis.

MethodIn this paper, we designed a system of measuring tree diameter which was mainly composed of embedded device and software platform.The embedded device included absolute encoder, wireless communication module, display screen, keyboard and ultrasonic sensor. And the platform included upper computer software, database and data management analysis software. When measurement started, the first step was to set measurement parameters and press the switch 1 to start the ultrasonic sensor to determine the height of the ground. When the screen display showed 1.3 meters high, the second step was to use the encoder to pull on the rope around the tree and then press switch 2. In the end, the upper computer software uploaded the data of DBH measured to the database, and then data management analysis software provided data query, statistics and analysis in a Web environment.

ResultThe experimental results showed that the measurement accuracy of the system was 99.97%, and the average single tree took 5.3 seconds, without the manual reading data, manual input data and data correction, and the work efficiency was significantly improved.

ConclusionsIn this paper, the portable system for measuring DBH, which has height measurement precision and efficiency, has the functions of data transmission, storage and analysis, realizes the multi-platform linkage of embedded, mobile terminal, database and Web, lays a good foundation for further research on the continuous perception and analysis of the growth of thoracic diameter at the same time.