The under-forest economy has received increased attention in China.However,little is known about the effects of co-composted biochar on soil and plant biomass in under-forest planting systems.In this study,plant biomass,soil nutrient levels,and bacterial communities were evaluated after application of biochar-based organic fertilizer (BOF,derived from co-composted biochar-compost) at varying rates to soils supporting Tetrastigma hemsleyanum Diels & Gilg planted under a Moso bamboo (Phyllostachys edulis) forest.BOF treatment increased the biomass of T.hemsleyanum.Compared with the control,BOF application significantly increased soil pH and organic carbon (SOC).The high-throughput sequencing results showed significant differences in the Bacteroidetes,Verrucomicrobia,Chlorofexi,and OD1 phyla among all groups.At the genus level,the control group was characterized by a preponderance of Conexibacter.Rhodanobacter was enriched in soils with a 3% BOF application and Steroidobacter and Spirochaeta were the most prominent phyla in the 5% BOF group.There was no biomarker selected in the 1% BOF group at the genus level.In conclusion,BOF application increased the biomass of T.hemsleyanum when intercropped under a Moso bamboo forest;this effect may be due to changes in the soil physicochemical properties and microbial communities after BOF application.