Vegetation Change Along the Arizona-Sonora Boundary∗

A segment of the international boundary dividing southeastern Arizona and northeastern Sonora provides an opportunity to examine the impact of culturally distinct land-use patterns on plant communities that were homogeneous prior to completion of a continuous fence line separating the two countries. Photographs taken in 1892, 1969, and 1976 illustrate the changing spatial contrasts in wild vegetation spanning the international boundary. Since the drought and overstocked range conditions of the early 1890s, there has been a general increase in herbaceous and woody vegetation. Presently, grass is taller and there is greater grass cover with less barren ground on the United States side. These conditions result from different grazing histories and different livestock management practices in the two countries.