荒漠草原土壤养分和植物群落稳定性对不同管理方式的响应

以宁夏短花针茅(Stipa breviflora)荒漠草原为研究对象,研究不同管理方式(放牧、补播改良和封育)对土壤养分及植物群落稳定性的影响,并分析土壤养分与植物群落稳定性之间的相关性.结果表明:不同管理方式对荒漠草原0～40 cm土壤养分含量影响显著,封育和补播有利于土壤有机质、全氮、速效磷和速效钾含量的积累,中等强度的自由放牧较封育降低了土壤有机质、水解氮和速效钾含量;土壤养分的垂直分布规律并不一致,土壤有机质含量和全氮含量5~15 cm土层高于表层,而速效磷含量和速效钾含量表现为0～5 cm最高.不同管理方式下的荒漠草原植物群落均处于不稳定阶段,相比之下封育5年和7年草地植物群落稳定性较高;群落稳定性与土壤速效钾含量成显著正相关关系,与其他养分含量无显著相关性.

Responses of Soil Nutrients and Plant Community Stability to Different Grassland Management Modes in Desert Steppe

The responses of soil nutrients and plant community stability to different management modes,as well as the correlation between plant community stability and soil nutrients were studied in Stipa breviflora desert steppe in Ningxia. The results showed that the management modes significantly affected the variation of soil nutrients in 0～40 cm soil layer (P <0.05). Enclosure and replanting accelerated the accumulation of soil nutrient contents such as soil organic matter, total nitrogen, available phosphorus and available potassium,whereas medium grazing regimes decreased the contents of soil organic matter,hydrolysable nitrogen and available potassium. The different grassland management modes led to the different vertical distribution patterns of soil nutrition. The highest organic matter and total nitrogen contents were in 5～15 cm soil layer,but the highest available phosphorus and available potassium contents were in 0～5 cm soil layer. The plant communities of desert steppe under different management methods were all instability, but the plant community stabilities of 7-year and 10-year enclosed grasslands were higher than that of other modes. Furthermore, there was a significantly positive correlation between plant community stability and soil available potassium content (P <0.05), while there were no significant relationships between plant community stability and other soil nutrients.