Abstract:Coriaria nepalensis, Pteridium aquilinum var. latiuscukum, Imperata cy lindrical var. major, and Quercus fabric were used as mulching materia ls to study their effects on the rhizosphere soil microbial population and enzym e activity and the tree growth in poplar plantation. The results showed that aft er mulching with test materials, the populations of both bacteria and fungi in r hizosphere soil were more than those of the control. Of the mulching materials, I. cylindrical and Q. fabric had the best effect, with the numbers of ba cteria and fungi being 23.56 and 1.43 times higher than the control, respectiv ely. The bacterial and fungal populations in rhizosphere soil increased with inc reasing mulching amount. When the mulching amount was 7.5 kg m-2, the num bers of bacteria and fungi in rhizosphere soil were 0.5 and 5.14 times higher than the control, respectively. Under bio-mulching, the bacterial and fungal po pulations in rhizosphere soil had a similar annual variation trend, which was ac corded with the annual fluctuation of soil temperature and got to the maximum in July and the minimum in December. The urease and phosphatase activities in rhizosphere soil also increased with increasing mulching amount. As for the effects of different mulching materials on the enzyme activities, they were in the order of C. nepalensis＞P. aquilinum ＞I. cylindrical＞Q. fabric. The annual vari ation of urease and phosphatase activities in rhizosphere soil was similar to th at of bacterial and fungal populations, being the highest in July and the lowest in December. Bio-mulching promoted the tree height, DBH, and biomass of poplar trees significantly.