The Pine Hollow aspen (Populus tremuloides) exclosures on the Ashley National Forest in eastern Utah were sampled in 1984, 19 years after they were established. The effects of 2, 4-D, wildlife, and cattle on plant succession were evaluated. Two exclosures were used to protect the sprayed area from (1) all animal use and (2) only livestock use. A third sprayed area was left open for use by all animals. The aspen overstory was killed as a result of spraying, with sufficient reproduction occurring to restock the stand. However, animal use drastically altered the aspen reproduction, as well as the understory production. Total protection favored desirable understory species while the open area had fewer desirable species.
United States Department of Agriculture, Forest Service, "Pine Hollow Exclosures: Effect of Browsing on an Aspen Community Sprayed With 2, 4-D" (1990). Forestry. Paper 70.