Abstract: In this paper, the dieback reasons of Abies fabri in Emei Mountain were interdisciplinarily investigated. Results show that the dieback of A.fabri trees is not significantly related to the aluminium content of soil and plant and destructive disease and insect pests, but is in close relationship with the development of swamp under the forest. The acid rain near Jinding, the top of Emei Mountain, can accelerate the growth of acidophilous moss and the development of swamp.

Key words: Abies fabri, Peat moss, High level swamp, Acid rain