For instance, buds for next year's growth will be set during the current summer. Even if when a more normal rainfall pattern returns, the effects of the drought of 1998 and 1999 will carryover to the next growing season, and maybe beyond. The width of tree growth rings is greatly affected by the availability of water. During dry years, little radial growth occurs and the annual growth ring will be narrow. Because severe droughts adversely affect trees in many ways, radial growth often will be reduced for the current year and maybe even one or more subsequent years.
Scientists can study the growth rings of old trees and determine rainfall patterns for years past.
This science is called dendrochronology. The general health of a tree depends a lot on where it is growing. Bottomland areas tend to be one of the most favorable sites for trees. There is usually adequate moisture coupled with deep, fertile soils. Sites that generally are not ideal for good tree health are ridges where shallow, eroded soils usually occur.