| In order to explore the influence of different enclosure years on soil properties and vegetation of Zhenglanqi,this paper selected sandy grassland with different enclosure years(0,3,7,1 0,15 years)in the area of Tugurigegacha in the map of Zhenglanqi as tlie research object,and took sandy grassland without enclosure measures as the control.Through field in,’estigation and indoor analysis,the change nile of soil and vegetation in sandy grassland conununity under different years of enclosure was analyzed.To provide scientific basis for restoration and reconstruction of degraded sandy grassland.The research results of this paper show that:(1).Impact on plant diversity.The investigation showed that The diversity index of shannon-wiener,the evenness index of Pielou and the biomass of the communities in the study area all increased significantly with the increase of the confining years(P<0.05),The lnaximum value(2.60,1.78 and 2205.22 g/m2)was reached at 15 years after encircling.Compared with the control group(1.36,1.24 and 212.11 g/m2),it was improved by 91%,5%and 939%.However,the increase of the above indicators was not significant after the encircling period exceeded 10 years(P>0.05).At the same time,the negative effect of Simpson index on vegetation restoration was considered.Therefore,after comprehensive consideration of enclosure cost,grassland utilization and the restoration effect of degraded grassland in this area,it can be seen that the comprehensive effect of enclosure on vegetation restoration in the study area reaches the optimal level when the enclosure age is 10 years.(2)Effects on soil physical and chemical properties.There was no significant difference in soil bulk density between 0 and 3 years(P>0.05).Tle results showed that the effect of short time enclosure on soil bulk density was not obvious.However,the soil bulk density decreased obviously when the confining years were 7～15 years.However,there was no significant difference in soil bulk density between different years.When the sealing age reaches 15 years,the maximum water holding capacity,capillary water holding capacity,minimum water holding capacity,organic matter,available nitrogen,available potassium,available phosphorus and soil cation exchange capacity all reach the maximum value in the soil layer of 0～20cm and the soil layer of 20～40cm.The soil layer of 0～20cm was respectively 59.15%,57.19%,67.77%,159.19%,69.57%,52.86%,41.87%and 82.47%higher than the control.The soil layer of 20-40cm was improved by 47.25%,47.59%,47.12%,22.56%,36.71%,53.54%,86.16%and 29.60%,respectively,compared with the control.The changes of total nutrients were not significant,and the pH value of soil presented a downward trend.(3)Effect on soil enzyme activity.When the encirclement time reaches 15 years,urine enzyle.soil invertase and soil alkaline phosphatase reach the maximum value in the soil layer of 0～20cm and the soil layer of 20～40cm.The soil layer of 0～20cm was 105.64,61.18%and 55.43%higher than the control.The soil layer of 20～40cm was 73.01%,119.68%and 38.81%higher than the control.With the increase of soil depth,the activity of catalase in so1l decreases.The catalase activity decreased gradually with the increase of the enclosing years.(4)Effects on soil microbial characteristics.After 15 years of enclosure,the number of bacteria,the number of actinomycetes,the number of fungi,the microbial biomass of carbon and the microbial biomass of nitrogen in the so1l layer of 0～20cm reached the maximum,which was 52.13%,58.63%,105.94%,105.23%and 1.61%higher than the control,respectively.In the soil layer of 20-40cm,the number of bacteria,the number of actinomycetes,the number of fungi,the microbial biomass of carbon and the microbial biomass of nitrogen reached the maximum,which were 65.75%,38.21%,69.70%,81.04%and 0.58%higher than the control,respectively.(5)Through the evaluation of the influence of different confining years on the comprehensive quality of soil and the use of principal component analysis(PCA),the results show that:With the increase of sealing years,the comprehensive quality of soil improved gradually.It peaked after 15 years of containment.However,after more than 10 years,the improvement of several key indicators in soil was not significant.After comprehensive consideration of the enclosure cost,grassland utilization and the restoration effect of the soil property in this area,for this research area,the enclosure period was 10 years,and the comprehensive effect of enclosure reached the optimal level. |
