Litter biomass and its carbon and nitrogen storage in four subtropical forests in central Southern China

Four subtropical forests with similar site conditions in the hilly area of Dashanchong Forest Park in central Hunan Province of China were selected to compare the existing litter biomass and its carbon(C) and nitrogen(N) storage.The litters were collected in the peak time of litter-fall.Among the four forests,Cyclobalanopsis glauca-Lithocarpus glaber mixed forest had the highest litter biomass(12.04±3.60 t·hm-2),followed by Pinus massoniana-L.glaber mixed forest(11.65±2.15 t·hm-2),Choerospondias axillaris forest(9.12±2.30 t·hm-2),and Cunninghamia lanceolata plantation(8.92±1.80 t·hm-2).In litter layer,leaf litter had the largest proportion,while fruit litter had the smallest one(5%).No significant differences were observed in the amounts of the litters with different decomposition degrees.The C concentration of the litters in the four forests ranged from 177.90 to 581.34 g·kg-1,and the N concentration varied from 5.18 to 15.48 g·kg-1.The C concentration of the litters decreased significantly with their decomposition degree(P 0.0001).The proportions of the semi-decomposed litter and decomposed litter in the forests had a negative correlation with the litter C/N.The litter C storage in the four forests ranged from 3.37 to 5.69 t·hm-2,and the N storage varied from 81.52 to 152.18 kg·hm-2.Because of the low litter decomposition rate and high existing litter amount,P.massoniana-L.glaber mixed forest had the highest C and N storage in its litter layer.