Ring widths of mature white oak trees were compared on 16 upland hardwood sites in the South Carolina Piedmont. Each site was classified as being in one of four community types forming a vegetation continuum along an environmental gradient ranging from xeric upland flats to mesic lower slopes. Ring widths were analyzed to determine the effect of climate on radial growth of white oak over the environmental gradient.
The ring-width chronologies of the xeric community types (1 and 2) showed more ring-to-ring variation then the more mesic community types (3 and 4), agreeing with the hypothesis of decreasing climatic stress from the xeric to mesic community types.
Based on response function analysis, important monthly climatic variables in white oak summerwood radial growth included: mean temperature for August, October, and December (prior year), March, May, June, and July (current year), and total precipitation for August and September (prior year), and January through June (current year). There were four more significant monthly climatic variables in the summer-wood ring-width response functions than in the total ring-width response functions, agreeing with the hypothesis that there is more climatic information in the summer-wood portion of radial increment than in total ring width.
Although visual analysis of total ring-width chronologies indicated that the length of the recovery period following a drought event was longer for trees on community type 1 (xeric) than on community type 4 (mesic), statistical analysis found no difference in the length of the recovery period between these two community types.