Researchers at the University of Connecticut Global Environmental Remote Sensing Laboratory have developed improved methods for detecting the signs of insect infestations within forests, according to an article from UConn Today.
The research, headed by Department of Natural Resources and Environment Assistant Professor Ze Zhu, focuses on using better sensing methods to more accurately determine the presence of trees damaged by insect infestation and prevent entire forests from decay. The program uses Landsat, a series of satellites controlled by NASA and the United States Geological Survey to acquire multiple enhanced photographs taken over time of a wooded area.
“CCDC (Continuous Change Detection Classification) is an algorithm that uses very dense satellite time series from Landsat, and by creating time series model based on past observations, CCDC can predict future observations, and if large differences are observed from future observations with predicted values consecutively, changes are detected,” Zhu said in an email.
While CCDC can capture rapid changes in forests, Zhu said he and his research team focus on more subtle signs of infestation that the algorithm cannot predict.
“When there is insect infection, usually we will see a small magnitude of deviation between model predicted and observed values, and in the image, you will see a reduce of greenness and wetness in forests” said Su Ye, a PhD candidate from the Clark University School of Geography, said in an email interview.
As a result, Ye developed a new model combining data from Landsat and on-site observations called PIDS: Parameter optimization, Index selection, Dynamic stratified monitoring, and Spatial consideration, according to UConn Today. Zhu and his research team have been using PIDS to better track deforestation in Connecticut.
“Now, we are investigating the whole CT forests thanks to the global observations of both Landsat and Sentinel-2, another satellite imagery program. Our most updated disturbance map shows that Litchfield County in northwestern CT underwent defoliation in summer 2021. Some local news reported this defoliation event and forestry scientists said it was caused by the gypsy moth” Kexin Song, a research assistant at UConn and a meteorology master’s student at Miami University, said in an email interview.
Gypsy moths, originating from Europe, have been the cause of deforestation across the United States for over a century. The larvae of the moths eat all the leaves from trees, preventing them from obtaining energy through sunlight and killing them. Zhu’s research primarily focuses on discovering these moths rather than how to eradicate them.
“In winter, people can remove egg masses from their trees. Furthermore, weak trees proximity to electricity powerlines can be risky. People can also do preventive tree trimming to lower the future outage risk during storms,” Song said regarding the treatment of infested trees.