不同干扰方式对呼伦贝尔典型草原生态系统特征的影响

Impacts of Different Disturbances on Ecosystem Characteristic of Typical Steppe in Hulun Buir

近年来剧烈的人类活动和自然因素变化致使生态系统退化,表现为草地植被退化、生物种类单一、土壤物理性质变差等。为了探讨内蒙古典型草地生态系统的结构和功能变化,以呼伦贝尔典型草原退牧还草工程区为研究对象,采用成对取样方法(围栏内-围栏外)对退牧还草工程区禁牧和休牧两种干扰方式下植被恢复过程中物种多样性、地上生物量、土壤容重和水分等的变化特征进行了研究,以期为草地的合理利用和管理提供理论依据。结果表明:(1)不同干扰方式对草地物种多样性和地上生物量有明显影响,物种的多样性指数和丰富度指数在禁牧区分别为1.73和7.59,在休牧区为1.47和5.70,全部表现为禁牧区>休牧区(P<0.05)。地上生物量则相反,在禁牧区和休牧区分别为36.34 g?m^(-2)和42.83 g?m^(-2),表现为禁牧区<休牧区;(2)不同干扰方式对草地土壤物理性状有明显影响,但不同指标对干扰方式的响应不同。禁牧有利于土壤含水量的积累,放牧导致土壤紧实、容重增加,同一土层深度土壤含水量表现为禁牧区>休牧区,例如0~10 cm处土壤含水量在禁牧区和休牧区分别为4.57%和2.80%,禁牧区显著高于休牧区(P<0.05);土壤容重则相反,表现为禁牧区<休牧区。综上所述,不同的生态工程措施对草原生态系统有明显影响,禁牧有利于维持较高的物种多样性和维持较好的土壤物理性质,休牧可提高草原生产力,退牧还草工程对恢复草原生态功能起到了积极的作用。

In recent years,grassland ecosystems have been degraded due to intensive human activities and the changes of natural factor.It leads to degradation of grassland vegetation,single species and poor physical properties of soil.In order to study the changes in the structure and function of typical steppe ecosystem in Inner Mongolia,this paper took the engineering area of returning land for grazing to pasture project in Hulun Buir typical steppe as the research object,the integrating method of outdoor sampling(in-fence&out-fence)was adopted,to analyze the changes of species diversity,aboveground biomass,soil bulk density and water content in the process of vegetation restoration under the two measures of banning grazing and delaying grazing.The results showed that,(1)Different disturbances had obvious impacts on the species diversity and the aboveground biomass of the grassland,the diversity index and richness index in the banning grazing region were 1.73 and 7.59 respectively and in the delaying grazing region were 1.47 and 5.70 respectively,and all were manifested as in order of the banning grazing region>the delaying grazing region(P<0.05).The aboveground biomass of the grassland in the banning grazing region and delaying grazing region was 36.34 g·m-2 and 42.83 g·m-2 respectively,showing the order of the banning grazing region<the delaying grazing region.And(2)different disturbances had obvious impacts on the soil physical properties,but the response of different indexes to interference patterns was different.The banning grazing was beneficial to the accumulation of soil water content,the delaying grazing led to soil compaction and increase in bulk density.Soil water content in the same layers were in order of the banning grazing region>the delaying grazing region,for example,in 0~10 cm,soil water content were 4.57%and 2.80%in the banning grazing region and delaying grazing region,respectively,showing that the former was significantly higher than the later(P<0.05).The soil bulk density was in order of the banning grazing region<the delaying grazing region.Generally,different ecological engineering measures have obvious influence on grassland ecosystem,the banning grazing region is propitious to maintain high species diversity and good soil physical properties,the delaying grazing is propitious to improve grassland productivity,and returning land for grazing to pasture project has a positive effect on rehabilitate the ecological function of grassland.