Recent Change in the Pattern of Tree Growth in Northern Arizona

Abstract

A significant change in growth pattern among the ponderosa pines (Pinus ponderosa Laws.) of the Flagstaff region, northern Arizona, occurred in 1947-1948. This is the first such change since 1904-1905. Evidence appears to verify the existence of a tension zone which fluctuates in altitude as a result of changes in the distribution and quantity of the rainfall as recorded through soil moisture.