Abstract:

Stellera chamaejasme is one of the most important poisonous plants to the livestock industry, and has become a dominant or common weed in northern and western grasslands of China. In order to determine the effect of S. chamaejasme spread on soil properties of grassland in farming-pastoral zone of Northern China, soil physical, chemical, and biological properties in occurrence and non-occurrence plots of Bashang grassland in Hebei province were measured. The results indicated that S. chamaejasme significantly increased water content of surface soil (0~10 cm) at its occurrence area in drought season (May-June), whereas no significant differences were found for soil bulk density, total porosity and capillary porosity in whole growth season compared to neighboring area without S. chamaejasme growth (non-occurrence area). S. chamaejasme had no marked effects on organic matter, total nitrogen, available nitrogen, available potassium content and soil pH at its occurrence area, while available phosphorus content increased significantly from May to September. At Stellera occurrence area, soil microbial biomass carbon, nitrogen and phosphorus increased significantly in July; activities of soil urease, phosphatase and sucrase increased significantly in the whole growth season; catalase and peroxidase activities were significantly higher from May to June, while the significant difference was not observed from July to September. S. chamaejasme can improve the growth conditions of water and available nutrient, increase soil biological activities of its occurrence area, thus enhance its competitive ability in grassland plant communities. Spread of S. chamaejasme was common in degraded grassland due to its stronger adaptive faculty, but it was not the reason for the grassland degradation.

Key words: Poisonous plant, Soil physical property, Soil chemistry property, Soil microbial biomass, Soil enzyme

摘要：

瑞香狼毒（Stellera chamaejasme）是我国主要毒草之一。为了明确瑞香狼毒对草地土壤性状的影响，在北方农牧交错带草原，于瑞香狼毒生长季（5-9月）连续取样分析了其发生区及邻近未发生区土壤的物理、化学和生物学特性。结果表明，瑞香狼毒发生区，表层土壤（0～10 cm）含水量在干旱季节（5-6月）显著高于未发生区，土壤容重、土壤总孔隙度和毛管孔隙度未见明显变化。发生区土壤有机质、全氮、碱解氮、速效钾含量以及土壤pH值与未发生区亦无显著差异，而5-9月速效磷含量显著高于未发生区。发生区7月微生物生物量碳、氮和磷显著高于未发生区。整个生长季土壤脲酶、磷酸酶、蔗糖酶活性均显著高于未发生区；过氧化氢酶活性5-6月显著高于未发生区，7-9月则与未发生区无显著差异；过氧化物酶活性5-6月亦显著高于未发生区，7-9月却显著低于未发生区。瑞香狼毒能在一定程度上改善土壤理化性状，提高土壤生物学活性。瑞香狼毒滋生蔓延不是造成草地退化的原因，而是草地退化导致的结果。

关键词: 有毒植物, 土壤物理性质, 土壤化学性质, 土壤微生物生物量, 土壤酶