The paper reported the study results on impacts of vegetation on chemical proper:tles of soil under forest. The study was conducted in some forest types in Luc Yen district (Yen Bai province) including 42-year-old naturally regenerated forests, 27-year-old naturally regenerated forests
19 years-old plantation of pure manglietia conifer and 10-year-old plantation of pure acacia mangium. The findings showed that the vegetation covers had eminent impacts on chemical properties of soil under forest, mainly increasing humidity, organic contents and therefore increasing fertility of soil (pH, humus, protein, P2O5, K2O, Ca2+ , Mg2+ exchangeable).