Abstract: Based on the study of pollen,stratum and ¹⁴C dating of Daqiao fen in Dunhua of Jilin Province,four pollen zones were distinguished, i.e.,Pinus-Picea-Abies assemblage (2 195±70～2 045±70 B.P.),Carex-Pinus-Betula-Corylus-Juglans assemblage (2 045±70～1 745±70 B.P.),Pinus-Corylus-Carpinus-Carex-Ranunculus assemblage (1 745±70～705±70 B.P.),and Pinus-Picea-Abies-Betula-Carex assemblage (705±70～1 950 AD).The vegetation changed from coniferous forest (similar to the vegetation currently found over 1 100 m a.s.l.in this area),through conifer-broad-leaved mixed forest (similar to the vegetation currently found between 400～600 m a.s.l.) and conifer-broad-leaved mixed forest (similar to the vegetation currently found between 600～800 m a.s.l.),to conifer-broad-leaved mixed forest (similar to the vegetation currently found between 800～ 1 100 m a.s.l.).Accordingly,Daqiao fen underwent the periods of gestation,fast development,expansion,and dieing out.

Key words: Phosphorus efficiency, Plant, High phosphorus use efficiency, Genotypes, Mechanism