As others have pointed out the article mentions this. I'm a bit skeptical, but I've also read a number of articles talking about how "unnatural" humans biology

As others have pointed out the article mentions this. I'm a bit skeptical, but I've also read a number of articles talking about how "unnatural" humans biology is due to our diet. AKA, maybe we have a higher mercury level concentration (artificial sweetener, or whatever) than local species and maybe that can be reflected and sensed in the trees. My skepticism is more about remote sensing. It wouldn't surprise me if these kinds of things can be detected when a tree's bark/leaves are chemically analyzed. OTOH, being able to sense that optically seems much harder.