As a Peace Corps volunteer, I lived in Botswana for a while in the 1980s. My village was right on the border with South Africa. Aerial photos show a dramatic

As a Peace Corps volunteer, I lived in Botswana for a while in the 1980s. My village was right on the border with South Africa. Aerial photos show a dramatic "step function" in how green each side of the border is (even during the dry season). I always heard the difference attributed to the free-ranging of goats and cows in Botswana, versus managed livestock in South Africa. From my experience (the goats are everywhere), may be. There also may have been large effects from burning wood on the Botswana side, versus gas cylinders in RSA, but that was outside my direct experience. I believe the border between Haiti and the Dominican Republic shows a similar effect.