The Effect Of Thinning On Fine Root Morphology、Nutrients And Turnover Of Chinese Fir Plantations

The fine root morphology、nutrient and turnover rate of four thinning intensities (CK:0%,LIT:30%, MIT:50%, HIT:70%) of Chinese fir (25years old) plantations in Nanjing Li shuiForest Farm were studied using sequence core method and litter bag. The results indicate that:1、The number of first-order roots accounted for80%of the first three orders of roots with thegreatest root length, the highest total nitrogen concentration, and the smallest carbon tonitrogen ratio.2、Compared with control, thinning significantly decreased the diameter of first-order roots inthird order root, but increase first-order root in fifth order root. The total C of fourcategories of first-orders, total N of first-order root in higher order roots (four and five rootorders) and C\N of first-order root in lower order roots (two and third order) weresignificantly increased under thinning, but thinning significantly decreased the C\N offirst-order root in higher order roots; The total N of first-order root in higher order roots weresignificantly decreased or increased.gest root length, the highest and lowest total N and C\N.3、Total FRB(＜2mm), non-target FRB, live and dead Chinese fir FRB in0~20cm soil layerwere198g.m2,50g.m2,97g.m2and51g.m2, respectively. Compared with control, the liveChinese fir FRB and non-target FRB were increased by10%and23%, but necromass ofChinese fir FRB decreased by14%.4、Annual dry mass loss, N accumulation, production and turnover were37%,33%,136g.m2and1.7a-1, respectively. To1~2mm fine root, thinning significantly decreased the annualdry mass loss and N accumulation by11%and43%. To0~1mm fine root, thinning has nosignificantly effect on its, annual dry mass loss, but the annual N accumulation wasdecreased for14%; The turnover rate of fine root (0~2mm) was significantly decreasedunder thinning.5、The correlation analysis indicate that soil temperature, total N and P and non-target fine rootbiomass have significantly relationship with the changes of fine root morphology, nutrient,biomass, decomposition and turnover rate..