| In the last decades, large-scale native forests have been converted to fast-growing and high yield commercial forest plantations to meet the demands for timber, fuel material, and other forest products. Some silvicultural measures, such as planting pure stands, clear cutting and slash burning, are widely applied during this conversion. Yield decline and land deterioration in such disturbed ecosystem has become serious. In this context, the ecological comparisons between native broadleaved forest and monoculture plantations are necessary in providing the implications for sustainable management. The forest floor is not only storage pools of carbon, nutrient and energy but a central, functional component of forest ecosystems. Coarse woody debris (CWD) also plays a substantial role in several ecological processes in forest ecosystems. However, few studies on forest floor and CWD have been conducted in natural and planted forests under same climatic and edaphic conditions in subtropical China. From 2001, the standing crop and seasonal dynamics of forest floor, its carbon and nutrient stocks, organic chemical properties, energy and water retention ability were studied in a natural forest of Castanopsis kawakamii (NF) and adjacent monoculture plantations of C. kawakamii (CK) and Chinese fir (Cunninghamia lanceolata, CF1) in Sanming, Fujian. In addition, dynamic hydrological role of forest floor, such as rainfall interception, water and soil conservation, was studied in plantations of Schima superba (SS) and Chinese fir (CF2) in Jianou, Fujian. The results showed that:(1) Forest floor masses were 8.99 t-hm-2 in the NF, 7.56 t-hm-2 in the CK and 4.81 t-hm-2 in the CF1 respectively; of the total amount, leaves constituted 64.96%, 61.38% and 38.05% respectively, twigs constituted 31.59%, 37.83% and 42.62% respectively. The average mass of CWD in the NF, CK and CF, were 1.28, 0.41 and 0.21 t-hm-2 respectively. The standing crop of forest floor in the NF and CK showed similar seasonal trend with the maximal value in spring. While for the CF), the forest floor mass peak occurred in summer. The seasonal trend of CWD mass was as follows: summer>spring>autumn>winter.(2) Carbon concentration in the L (litter) layer was higher than that of the F (fragmented) layer. Carbon storage in forest floor of the NF, CK and CFj were 4.02, 3.29 and 2.28 t-hm-2 respectively. Significant difference of stocks of forest floor C was found between NF (or CK) and CF, (P<0.05). Carbon pools in CWD were greatest in the NF, being 4.11 times and 7.09 times as much as that of the CK and the CFi, respectively. Seasonal pattern of C pools in forest floor was similar to that of forest floor masses.(3) Concentrations of N, P and K in forest floors of the NF and CK were higher than those of the CF). In contrast, Ca and Mg concentrations were the highest in the CF|. Twig litter inthe L layer had lower nutrient concentrations than those in the F layer. Nutrient storage in forest floors ranged from 138.42 kg-hm-2 in the NF to 72.39 kg-hm-2 in the CF1. Except for the highest Mg stock in the forest floor of the CK, the amounts of N, P, K and Ca storage were the highest in the forest floor of the NF.The NF had the highest nutrient concentrations of CWD in L layer. While for F layer, P and Mg concentrations of CWD were highest in the CK. Nutrient pools in CWD varied considerably among forests, with greatest values for NF (14.16 kg-hm-2), followed by CK (2.90 kg-hm-2) and CF1 (0.95 kg-hm-2). Nutrient storage in CWD in the three forests followed the sequence of N>Ca >K>Mg>P.(4) Concentrations of water soluble compounds and cellulose in leaf and twig litter of the L layer decreased during the decomposition, while increases of concentrations of alcohol soluble compounds and coarse protein were found in twig litter. Maximum storage of water soluble compounds, lignin, coarse protein, hemicellulose and cellulose were observed in leaf and twig litter of the forest floor in the NF, while the forest floor of the CK had the greatest amount of a...
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