该文对东营市垦利县柽柳(Tamarix chinensis)林、枣(Ziziphus jujuba)园、旱柳(Salix matsudana)林、刺槐(Robinia pseudoacacia)林、白蜡(Fraxinus chinensis)林、桑(Morus alba)园土壤酶活性及其与土壤化学性质和土壤微生物的关系进行了分析。结果表明:在土壤空间上,脲酶和过氧化物酶活性随土层的增加而减小,多酚氧化酶和过氧化氢酶的活性在土层之间变化不明显。过氧化氢酶与脲酶和多酚氧化酶显著相关,脲酶与多酚氧化酶呈负相关。不同造林模式对土壤过氧化氢酶和过氧化物酶影响不大,对脲酶和多酚氧化活性有显著的影响。各种造林模式增加了脲酶的活性,均高于柽柳林;减小了多酚氧化酶的活性,除刺槐林外,均显著低于柽柳林;而造林模式对过氧化物酶和过氧化氢酶的影响较小。土壤酶活性与土壤养分有一定的相关,其中脲酶与全氮、有机质显著正相关,与速效氮正相关;多酚氧化酶与速效钾正相关,而过氧化氢酶与全氮、速效磷和有机质呈负相关,与土壤pH值相关性不显著;与微生物的相关系数不大,其中脲酶与固氮菌、纤维素分解菌显著正相关,与细菌正相关;多酚氧化酶与固氮菌和细菌负相关;过氧化氢酶与固氮菌显著负相关,与纤维素分解菌负相关。脲酶和多酚氧化酶可以作为滩地土壤质量评价的指标。

Background and Aims More attention is being paid to utilization of the ecological resources in the lowlands of the Yellow River Delta. However, most proposed measures emphasize breeding, irrigation and cultivation. Soil enzymes play an important role in soil biochemical processes, such as litter decomposition, nutrient fixation and nutrient release. Insufficient attention has been paid to the relationships among soil enzymes, soil microbes and soil physical-chemical quality, yet such study can indicate the dynamic process of soil nutrients and soil health. Our objectives were to determine: 1) the distribution of soil enzymes of different plantations at different soil depths, 2) the correlations among microbes, soil nutrients and soil physical and chemical characteristics and 3) soil enzymes that are key factors in maintaining soil fertility.

Methods We analyzed soil enzymes, soil chemical characteristics and soil microbes for six kinds of plantations (Tamarix chinensis, Salix matsudana, Robinia pseudoacacia, Fraxinus chinensis, Ziziphus jujube and Morus alba) in Kenli County, Dongying, Shandong Province. Soil samples were collected at 0-20 cm and 20-50 cm depths. Established methods were used to analyze soil enzymes and soil physical and chemical characteristics. Analysis was done using an integrative method combining correlation and component analyses in SPSS.

Key Results Soil urease and soil peroxidase decrease with increasing soil depth. There are positive relationships between soil peroxidase and soil urease, and soil peroxidase and soil polyphenol oxidase, while there is negative correlation between soil urease and soil polyphenol oxidase. The kind of plantation clearly affects soil urease and soil polyphenol oxidase, but not soil catalase and soil peroxidase. Soil urease activity of different plantations is higher than that of the Tamarix chinensis forest; the soil polyphenol oxidase activity is lower than that of the Tamarix chinensis forest, except for the Robinia pseudoacacia forest. There are close correlations among soil enzymes and soil nutrients, and few correlations with pH values and soil microbes. Among them, soil urease shows positive relationships with total N, organic C and available C. Soil polyphenol oxidase shows a positive relationship with available K and negative relationships with soil catalase, total N, available P, organic C, peroxidase and soil urease.

Conclusions This study suggests that plantation type affects soil enzyme activities. The activities of soil urease and soil polyphenol oxidase can be regarded as indexes to assess soil quality in the lowlands.