围封条件下荒漠草原两种植物群落土壤理化性状与酶活性的研究

Studies on the soil physical and chemical properties and enzyme activities of two fenced plant communities in desert steppe grassland

围栏封育是退耕还林还草工程措施之一,不仅有助于草场植被的恢复,也有助于土壤特性的改善。以宁夏盐池县荒漠草原沙芦草群落和苦豆子群落为研究对象,通过对土壤基本理化性状及4种常见土壤酶活性的测定,研究围封内外两种植物群落的土壤理化性状与酶活性的变化特征。结果表明:1)较围栏外,围栏内的沙芦草群落0~10cm土壤含水量、全氮、全磷均显著提高,土壤容重、pH值、碱解氮和速效磷含量显著降低,10~20cm和20~40cm土层的土壤理化性状之间无显著差异;苦豆子群落除土壤容重显著降低外,围封显著提高了土壤含水量、pH值、有机碳、全氮、全磷、碱解氮和速效磷含量。2)围栏内沙芦草群落中土壤脲酶活性显著降低,而土壤蔗糖酶活性在表层(0~10cm)显著提高,过氧化氢酶和磷酸酶活性变化不显著;苦豆子群落围栏内土壤磷酸酶活性显著降低,蔗糖酶和脲酶的活性显著提高,过氧化氢酶活性变化不显著。3)两种植物群落中的土壤酶活性与土壤理化性状之间的相关性不同。苦豆子群落中土壤蔗糖酶活性、土壤脲酶活性与土壤养分之间均极显著正相关(P<0.01),而磷酸酶活性与之呈负相关关系;沙芦草群落中脲酶活性与土壤有机碳、全磷、速效磷含量均为极显著正相关关系(P<0.01),而过氧化氢酶活性与土壤有机碳、全氮、碱解氮含量之间呈显著正相关关系(P<0.05)。研究证实,围封尽管能够增加2种植物群落的表层土壤(0~10cm)含水量和土壤养分,但对4种土壤酶活性的影响没有表现出明显的规律性。

Enclosure (fencing) is a fundamental part of China's current 'Grain for green' program,and facilitates both the recovery of vegetation,and the improvement of soil properties.This paper,reports research into the recovery of soil physical and chemical properties and changes in activities of 4 soil enzymes after fencing in Agropyron mongolicum,and Sophora alopecuroides plant communities in the desert steppe of Ningxia province.Adopting the method of space as a substitute for time,the typical sites of two communities were selected and investigated in Yanchi County of Ningxia.The results showed that: 1) After fencing,soil water content,total N and total P increased significantly;while soil bulk density,pH,alkali hydrolysable N and available P contents were significantly reduced in the 0-10 cm soil layer of the A.mongolicum community studied.However,there were no significant differences in soil physical and chemical properties in the 10-40 cm soil depth.In the S.alopecuroides community soil bulk density decreased significantly,while soil water content,pH,organic carbon,total N,total P,available N and available P were significantly increased in the 5-10 cm soil depth.2) After fencing,in the A.mongolicum community soil urease activity decreased significantly,while soil sucrase activity in the surface layer (0-10 cm) significantly increased,and the activity of catalase and phosphatase did not change significantly.In the S.alopecuroides community soil phosphatase activity decreased significantly,the activities of sucrase and urease were significantly increased,and the activity of catalase changed non-significantly.3) There were different correlations in the two plant communities between soil enzyme activities and soil physical and chemical properties.In the S.alopecuroides community there was a significant positive correlation between soil sucrase activity,soil urease activity and soil nutrient content (P< 0.01),while the activity of phosphatase showed a remarkably negative correlation.In A.mongolicum communities,there were significant positive correlations between urease activity and soil organic carbon,total P and available P content,and also,significant positive correlations between catalase activity and soil organic carbon,total N,and alkali hydrolysable N (P<0.05).In conclusion,although the water content and soil nutrient status of surface soil (0-10 cm) of the two communities were increased by fencing,no consistent changes in activities of the 4 soil enzymes studied were found.