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What do high-elevation oak tree-rings say about past climate?

posted May 3, 2012, 5:23 PM by Christopher Crawford   [ updated May 4, 2012, 9:28 AM ]

If you travel to western North Carolina, USA, you will encounter mountainous terrain. If you put on your hiking boots, and then climb in excess of 3000 feet, you will be standing at some of the highest points (elevation wise) in eastern North America. If you choose to look around for a bit, you will find big gnarly oak trees that are probably between 200 and 400 years old. If you happen to look up, you will notice that the canopy above is rather open. At night, you can even see the stars and moon without obstruction.

Well, as it turns out, these old oak trees near your tent have something to say about how much it has rained, and how cold it has been since the early 1600s.  The problem is, these trees, and their annual growth rings, do not record temperature and precipitation change from year to year very well. Instead, they seem to tell something about how temperature and precipitation has changed over decades, not years! Besides, temperature and precipitation across the Southern Appalachian Mountain Range only varies together in a significant way during winter and summer seasons. This leaves out fall and spring, a time when deciduous oak trees like to either slip into dormancy or begin growing vigorously.

What these trees are saying about past climate is still an open question? More study is needed to determine the nature of how these particular tree-rings record temperature and precipitation, and in return, what that says about how climate has varied across southeastern North America since the middle of the Little Ice Age and early European settlement. Stay tuned, these tree-rings likely have something grand to say, but it will simply require more work!

For specific details, see the doi link to Crawford, C.J. 2012. Do high-elevation northern red oak tree-rings share a common climate-driven growth signal? Arctic, Antarctic, and Alpine Research 44:26-35 on the publications page of this website.