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对桂西北杉木光皮桦混交林和杉木纯林的对比研究表明 ,35年生杉桦混交林的立木蓄积量为 4 4 1 0 87m3·hm- 2 ,比杉木纯林高 3 6%。混交林枯枝落叶层现存量及其N ,P ,K ,Ca ,Mg等元素的质量浓度分别为 13 18t·hm- 2 ,158 3,6 1,16 5,86 3和 32 3kg·hm- 2 ,分别比杉木纯林高 9 7% ,76.7% ,69.4 % ,96.4 % ,83.2 % ,17.0 %。混交林地 ( 0～ 10 0cm)土壤容重为 0 81～ 1 2 2g·hm- 3,比杉木纯林低 1 0 %～ 8 0 % ,而土壤孔隙度 ,通气度和持水量分别比杉木纯林高 2 0 %～ 3 9%。土壤有机质、全氮、水解氮、有效磷和速效钾分别比杉木纯林高5 5%～ 4 9 8%。
The comparative studies on the mixed Betula platyphylla bungeana and Cunninghamia lanceolata plantations in the west of Guangxi showed that the stand volume of the 35-year-old Betula platyphylla mixed forest was 441 0 87m3 · hm-2, which was 36% higher than that of the pure Chinese fir plantation. The existing stock of litter layer and the concentrations of N, P, K, Ca, Mg and other elements in mixed forest were 13 18 t · hm-2, 158 3,6 1,16 5,86 3 and 32 3 kg · hm- 2, respectively, 9 7%, 76.7%, 69.4%, 96.4%, 83.2% and 17.0% higher than pure Chinese fir plantation, respectively. The bulk density of the soil ranged from 0 to 100 cm in the mixed forest was 0 81 ~ 122 g · hm-3, which was 10% ~ 80% lower than that of the pure Chinese fir plantation, while the soil porosity, aeration and water holding capacity were respectively High 20% ~ 39%. Soil organic matter, total nitrogen, hydrolyzed nitrogen, available phosphorus and available potassium were respectively 55% ~ 498% higher than pure Chinese fir plantations.