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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/ hm2 ,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五种元素的积累量分别为 13.18t/ hm2 和 2 99.5kg/ hm2 ,分别比杉木纯林高 9.7%和 69.9%。混交林地 ( 0～ 10 0 cm)土壤容重为 0 .81～ 1.2 2 g/ cm3,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 study on the mixed forest of Betula luminifera and Betula platyphylla in western Guangxi showed that the stand volume of 35-year-old Betula platyphylla mixed forest was 44.07% 87m3 / hm2, which was 3.6% higher than the pure Chinese fir plantation. The existing amount of litter layer and the accumulation of five elements of N, P, K, Ca and Mg in mixed forest were 13.18 t / hm2 and 2 99.5 kg / hm2, respectively, which were 9.7% and 69.9% higher than pure Chinese fir plantation respectively. The bulk density of the soil ranged from 0 to 100 cm in the mixed forest was 0.81-1.22 g / cm3, which was 1.0% -8.0% lower than that in the pure Chinese fir plantation, while the porosity, air permeability and water holding capacity of the soil were 2 .0% ~ 3.9%. Soil organic matter, total nitrogen, hydrolyzed nitrogen, available phosphorus and available potassium were 5.5% -4.88% higher than pure Chinese fir plantation respectively.