Litter production, seasonal pattern and nutrient return in seven natural forests compared with a plantation in southern China

The amount and pattern of litterfall and its nutrient return were studied in seven natural forests of Schima superba Gardn. and Champ. (SCS), Castanopsis fabri Hance (CAF), Tsoongiodendron odorum Chun (TSO), Cinnamomum chekiangense Nakai (CIC), Altingia gracilipes Hemsl. (ALG), Castanopsis carlesii (Hemsl.) Hayata (CAC) and Pinus massoniana D. Don (PIM), and compared with that of an adjacent 29-year-old plantation of Chinese fir (Cunninghamia lanceolata Lamb.) (CUL) in Jianou, Fujian, China. Mean annual total litterfall over 3 years of observations varied from 4.63 Mg ha^-1 in the CUL to 8.85 Mg ha ^-1 in the PIM; of this litterfall, the leaf contribution ranged from 62 to 73 per cent. Litterfall in the CAF, ALG and CAC showed an unimodal distribution pattern, while for the five other forests, the litterfall pattern was multi-peak. The rank order of the eight forests, according to nutrient return mass with the exception of P, was different from the order when rank was according to total mass of litterfall. The highest annual N, K and Ca returns from total litterfall were noticed in the TSO, the CAF and the CUL, respectively. The amounts of P and Mg potentially returned to the soil were the highest in the PIM. The leaf fraction provided greater potential returns of N, P, K, Ca and Mg to the soil than other litter fractions. The results of this study demonstrate that natural forests have a greater capability for maintaining site productivity than the monoculture coniferous plantation, due to higher amount of above-ground litter coupled with greater nutrient returns; therefore conservation of natural forests is recommended as a practical measure in forest management to realize sustainable development of forestry in mountainous areas of southern China.