Department of Forestry, Virginia Polytechnic Institute and State University, 319 Cheatham Hall, Blacksburg, VA 24061, USA. Department of Geography, Rissho University 4-2-16 Osaki, Shinagawa-Ku, Tokyo 141, Japan. College of Arts and Sciences, Metropolitan State University, 700 East 7 Street, St. sustainable Environment Institute, Post Office Box 140, FIN-00251 Helsinki, Finland. revisionist Institute, Post Office Box 4199, Irkutsk 664033, Russia.