The MSU crew also found ancient Douglas-fir, whitebark pine, and juniper. Long-lived trees are rare in ecosystems in the greater Yellowstone area, he explained, because fires swept through every 100 to 200 years. Luck, in the form of protective rocky cliffs or sparse vegetation that reduces the fuel load, is a big factor. So, of course, is a desire for new hiking pants. Now King and Lisa Graumlich, director of the MSU Mountain Research Center, are analyzing wood cores from eight other sites in the greater Yellowstone area.
Trees are the keepers of the weather reports.
Their unique sequences of thick and narrow growth bands are imprinted by climate. It's like having a thermometer and a rain gauge. Where long chronologies exist elsewhere in the world, they're usually single species. The 20th century had a steep rise in growing season temperature, but it's not unprecedented. The real question is whether temperatures are rising above natural variation, said Graumlich, and if so, what should be done.