dr. crabtree: this is what's called released willow.o this is high-stature willow that really erupted in 1997 and 1998 and it's surrounded by smaller willow that has not released. narrator: using the remote-sensing images in conjunction with the data gathered in the field gives the team a better understanding of the landscape and how it impacts the various tiers in the food web. the researchers have found that willows that escape browsing height create a domino effect within the ecosystem. species like riparian songbirds, insects, and, in particular, rodents, have come back into these preferred habitat types, and other species are starting to respond. for example, fox and coyotes are moving into these areas because there's more prey for them. and there's been an erupting trophic cascade in some of these lush willow riparian habitat sites. narrator: while the willow populations appear to be rebounding, scientists are working to determine how much of this regrowth can be attributed to the wolves as compared to other contributing factors.