Tree rings can supply us with valuable information about past weather
events.
They can tell us if the weather resulted in a good growing season, or a
drought. They can identify years in which there were forest fires.
Trees that are very slow growing can supply records back over long periods
of time
A 3,000-year record from 52 of the world's oldest trees shows that
California's western Sierra Nevada had frequent droughts and fires between
the years 800ad to 1300ad