The Use of Repeat Photography to Document Changes in Aspen Communities in the West

Historical repeat photography provides valuable data on long-term vegetation change and land management practices. Repeat photography is also of great educational value because it is easily interpreted by the general public. To date, 800 photo sets have been repeated in Southern Utah and placed on the Utah State University Extension web site (http://www.ext.usu.edu/rra). By systematically evaluating vegetation changes in these photos some clear trends emerge; range conditions have improved, soil erosion has decreased, riparian and stream conditions have improved, while conifers, pinyon-juniper and sagebrush have greatly increased in area and density. Aspen is depicted in 223 repeat-photos in South-Central Utah. In 64% of the photosets, aspen declined, while it remained unchanged in 27% and increase in 9%. This is similar to other research that has reported a major decline in aspen across the Intermountain West. Where aspen declined, it usually was replaced by invading conifers. Conifers were depicted in 221 repeat-photosets and in 92% of those images conifers increased markedly. To stop the decline of aspen and return it to its former abundance, disturbance mechanisms must be instituted that remove conifers and stimulate aspen suckering, controlled burning is the preferred alternative in many situations, however where burning is not practical, mechanical means can be used to restore aspen.