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对建立在广西合浦县山口林场、广西钦州市三十六曲林场和广西武鸣县朝燕林场的尾叶桉 (Eucalyptusurophylla)、窿缘桉 (E exserta)、马占相思 (Acaciamangium)纯林以及尾叶桉马占相思混交林的凋落物量及其养分含量和土壤养分等因素进行研究 ,结果表明 :( 1)马占相思林地土壤养分元素含量大于尾叶桉和窿缘桉林地土壤养分元素含量 ,马占相思造林后土壤的养分元素含量提高的幅度较大 ;( 2 )混交林的凋落物量大于尾叶桉、马占相思纯林 ,凋落物大部分养分元素含量比尾叶桉纯林的高 ,P、K、Mg等少部分元素含量也高于马占相思 ;另外 ,凋落物的全量N、P和速效B含量分别与土壤的全量N、P和速效B含量有显著的正相关关系。( 3)混交林能有效增加土壤养分元素含量 ,提高土壤肥力 ,混交造林 3年后土壤全量N、P、K以及速效B和Mg元素含量分别增加 2 9 5 %、 77 3%、 5 3%、 6 7%、 6 0 %。 ( 4 )混交林土壤养分元素含量高于尾叶桉纯林 ,3年后全量N、P、K与速效B和Mg元素及有机质的含量比尾叶桉纯林分别高出 5 2 %～ 87 0 %、 19 6 %～5 6 7%、 7 7%～ 5 4 2 %、 2 5 %～ 12 8 6 %、 12 5 %～ 33 3%、 9 5 %。部分养分元素含量高于马占相思纯林。 ( 5 )比例不同的混交林对土壤养分的影响不同 ,作用较大的尾叶桉与马
Eucalyptus urophylla, E exserta and Acacia mangium pure forests established in Shankou Forest Farm, Hepu County, Guangxi Province, 36 forests in Qinzhou City, Guangxi Province and Chaoyin Forest Farm in Wuming County, Guangxi Province, Eucalyptus urophylla and Acacia mangium mixed forest were studied. The results showed that: (1) The content of soil nutrient elements in Acacia mangium forest land was greater than that in Eucalyptus urophylla and Eucalyptus grandis forest (2) The amount of litterfall in mixed forest was greater than that of Eucalyptus urophylla and Acacia mangium plantations, and the content of most nutrient elements in litter was higher than that of pure plantation of Eucalyptus urophylla, P, K and Mg were also higher than that of Acacia mangium. In addition, the contents of total N, P and available B in litter were positively correlated with the contents of total N, P and available B in soil, respectively. (3) The mixed forest can effectively increase the content of soil nutrient elements and increase the soil fertility. After three years of mixed forestation, the contents of total N, P, K and available B and Mg in soil increased by 259%, 77%, 53% , 67%, 60%. (4) The contents of soil nutrient elements in mixed forest were higher than those in Eucalyptus urophylla. After 3 years, the content of N, P, K and available B, Mg and organic matter were 52% ~ 87 0% higher than pure Eucalyptus urophylla, 19 6 to 5 6 7%, 7 7% to 5 4 2%, 25% to 12 8 6%, 125% to 33 3%, 95%. Some nutrients are higher than Acacia mangium pure forest. (5) Different proportion of mixed forest have different effects on soil nutrients, the larger role of Eucalyptus urophylla and horse