Biocrusts affect soil detachment through above-ground(top crust\'s surface covering)and below-ground(sub-crust\'s binding and bonding,B&B)effects,which might vary with biocrust development or coverage.However,these effects in humid climates are still unclear.This study was conducted to apportion and quantify the surface covering and B&B effects of moss biocrusts with five coverage levels(1％-20％,20％-40％,40％-60％,60％-80％,and 80％-100％)on soil detachment by overland flow in a subtropical humid climate.Two treatments with one being intact moss crusts and one removing the above-ground moss tissues were designed for each coverage level,and bare soil was used as the baseline.The results indicated that soil detachment capacity(Dc)and rill erodibility(Kr)decreased with biocrust coverage.After removing the above-ground moss tissues,the impeding effect of biocrusts on soil detachment weakened,but still increasing soil erosion resistance relative to bare soil.For intact crust,Dc was reduced by 50％-95％compared with bare soil,wherein 36％-55％and 14％-40％were attributed to the surface covering and B&B,respectively.The top crust contributed more than sub-crust to the soil detachment reduction,which were related to but not linear with biocrust coverage.When biocrust coverage reached mid-to-higher level(40％-100％),both top crust and sub-crust steadily contributed to soil detachment reduction with 60％and 40％,respectively.The findings advance a better understanding of the influencing mechanism of biocrusts on soil erosion in humid climates and highlight the importance of saving biocrusts as ecosystem functions.