典型草原恢复演替过程中土壤性状动态变化研究

Research on the dynamic changes of soil properties of typical steppe in the restoring process

为探讨典型草原恢复演替过程中土壤性状的变化规律,在内蒙古太仆寺旗典型草原选取不同围封年限,处于不同恢复演替阶段的生长季围封(4-9月围封)恢复草地为研究对象,同时选取自由放牧草地为对照,开展典型草原恢复演替过程中土壤物理、化学和生物学特性的系统研究。结果表明,1)典型草原恢复演替过程中,土壤性状发生了一系列演变,与自由放牧草地相比,围封7,10,13,20年,土壤0～30cm土层容重显著下降,<0.05mm的粘粉粒含量和孔隙度显著增加(P<0.05);土壤有机质、全氮、全磷、速效氮、速效磷、速效钾、微生物数量、微生物量碳、微生物量氮显著增加(P<0.05),酶活性增强,以0～10cm土层增加最为明显,表现出明显的表聚现象。2)典型草原在围封恢复过程中若连续多年刈割利用,容易导致土壤结构再次恶化,土壤质量下降,草地发生二次逆行演替。因此,退化草地恢复演替过程中的合理利用问题(如合理的割草制度)有待进一步研究。

Soil properties of typical steppe response to restoring succession progress were measured in a grassland experiment site in Taipusi county of Inner Mongolia,China.The grasslands have been exclosed（April to September every year） for 7,10,13 and 20 years,respectively.Soil samples were collected in mid-August in 2008,and soil physical properties,chemical properties as well as biological properties were monitored.Results showed that the soil properties presented a series evolution tendency during grassland restoration succession process.Compared with continuous grazing areas,exclosing treatment over 7 to 20 years significantly decreased the soil bulk density in the layer of 0-30 cm（P0.05）,and increased both silt-clay content and soil porosity（P0.05）.In addition,exclosed grasslands had significantly higher soil organic matter,total nitrogen,total phosphorus,available nitrogen,available phosphorus,available potassium,microbe quality and microbial biomass than continuous grazing areas,especially in the layer of 0-10 cm.Soil structure and quality could be deteriorated again and recovered grassland would present the second retrogressive succession due to continuous hay cutting.Further studies are needed to investigate rational use of typical steppe during their restoring process.