Bill Mollison - Source: permacultureprinciples.com
"Approximately every 100 m of altitude is equivalent to 1° of latitude, so that a variety of plants can be grown if the property contains hills and flats. In the sub-tropics, even temperate-area plants can be grown on high islands or hills."
~Bill Mollison
Permaculture: A Designers Manual - 1989
Page 135
