Lichens live at the mercy of local climate. They absorb and lose water like a sponge, unlike plants, which rely on roots to tap soil water and leaves with waxy coatings to slow water loss. Hot or dry conditions cause a lichen to dry up and become dormant until favorable weather returns. Over time, changes in temperature and precipitation affect which lichen species can survive in a forest, making scientists wonder whether lichens are harbingers of climate change. So far, the development of lichen-based tools for monitoring climate is still in its infancy. Data from the Forest Service's Forest Inventory and Analysis Program were used to examine lichen communities across southeastern and south-central Alaska. Using Alaska's diversity of climate zones as a reference, lichen species showing a pronounced affinity for a particular assemblage of climatic conditions were identified as indicator species. Twelve indicator species were found, each associated with different optimal levels of wetness and temperature. Models looking at lichen communities were used to pinpoint geographic regions where rapid species turnover is expected as a result of climate change. The most rapid change is expected in the sub-oceanic zone, a narrow belt of forest sandwiched between the wet forests of the coast and dry inland forests.