杨树不同品种更替连作对林地土壤生化特性的影响

通过对山东莒县沭河流域不同杨树品种更替连作人工林林地土壤调查研究，发现不同品种更替连作林地与对照林地（非更替连作）土壤速效氮、速效钾、速效磷、微量元素Cu，Zn含量基本相等，但前者有机质含量显著高于对照，土壤微量元素Mn含量显著低于对照。更替连作林地与对照林地相比，土壤脲酶活性平均提高184．7％，过氧化物酶的活性平均提高40．5％，过氧化氢酶活性降低11．8％，三者与对照相比差异显著。多酚氧化酶活性较对照提高32．3％，但未达到显著水平。随着土层加深，土壤脲酶活性逐渐降低，而其它酶活性的垂直分布规律不明显。更替连作林地土壤真菌、细菌、放线菌数量显著高于对照林地。

Effcet of Alternative Continuous Cropping of Different Poplar Cultivar on Soil Biochemical Properties

Effects of alternative continuous cropping of poplar cuhivars on soil biochemical properties along Shu River in Ju county, Shandong, were studied. Results showed that, content of available N, P, K and trace element of Cu and Zn were same between alternative continuous cropping and unahernative continuous cropping, but soil organic matter and trace element Mn were different signifcantly. Soil organic matter in alternative continuous cropping treatment was higher, but trace element Mn was lower than unahernative continuous cropping treatment. Compared with unalternative continuous cropping, soil enzyme activity of urease and peroxidase in alternative continuous cropping treatments increased significantly by 184.7 % and 40. 5 %, but catalase decreased significantly by 11.8%. And polyphenol oxidase activity increased by 32.3% with no significant difference between treatments and CK. With soil depth increased, urease activity decreased steadily, and the other three enzymes had no variety trend. The quantity of soil fungi, bacteria, actinomyces in alternative continuous cropping treatments was higher than that of CK, signifcantly.