We can’t see bugs from space, but we can see the effects of insect infestation in Landsat imagery. An unprecedented mountain pine beetle epidemic started in the Black Hills of South Dakota in 1996 and has damaged about 430,000 acres of forest land. The pine beetle, about the size of a grain of rice, is killing ponderosa and other pines throughout the Black Hills.
Normally, the mountain pine beetle contributes to the health of a forest by infesting and killing older and stressed trees, which helps make the forest more productive. However, the recent large outbreak is doing more harm than good. It can affect water quality. It can convert the forest from a carbon sink to a carbon source. And where insect outbreaks and forest disturbance caused by wildfire overlap, the effects can actually be both harmful and beneficial. All of the effects of an outbreak need to be monitored.
Mountain pine beetles usually live in small numbers. It’s normal for the population to boom occasionally, but the current epidemic is unprecedented. Beyond the Black Hills, pine beetle outbreaks have occurred extensively in many pine forests throughout western North America, from British Columba in Canada to New Mexico.
In these Landsat images, beetle infestation is typically indicated by a washed-out pinkish color as seen in the top center and lower right of the images. The more pronounced pink region in the lower left of these images is a burn scar from the Jasper Fire, which occurred in 2000.
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