| Abstract |
As an important component of the urban ecosystem, trees provide many environmental, social and economic benefits. To help better understand the impact of micro-climate effects on tree health and growth, a LoRaWAN-based environmental sensor system consisting of a soil temperature sensor, a soil moisture sensor, and an air temperature/humidity sensor was developed and tested on Columbia University's Morningside Campus at the site of a linden tree, which was instrumented with a point dendrometer in order to measure the tree trunk's radial growth. The use of LoRa technology enabled the system to operate with low-power and to wirelessly communicate with the internet-connected gateway at long distances. The gateway's coverage was established throughout the entire 480m × 260m area of the campus, with an average received signal strength indicator (RSSI) between -120.0 and -83.0dBm. Ecological and climate data were collected over a 9-day test period of the system. The results show that the air temperature and the air humidity were highly negatively correlated, with a Pearson's correlation coefficient r=-0.65, P<0.0001. Additionally, the soil and air temperatures were found to be cross correlated, with a time lag of 390mins (or 6.5hrs), and with r=0.33, P<0.0001. From the dendrometer, the tree trunk was found to grow at a rate of about 20.53m/day. The hourly radial change of the tree diameter was found to be negatively correlated with the air humidity, with r=- 0.21, P<0.01. © 2021 IEEE. |
