Study On The Soil Microorganism And Soil Enzyme Activities In Process Of Artificial Restoration For Degradated Grassland

Through studying on the number of soil microorganisms (fungi, actinomycetes and bacteria),soil enzyme activities and microorganism physiological groups of four degradated grassland with different restoration years by using plate colony count and MPN methods, grassland types included unrestoration grassland, artificial recovered for 3 years, artificial recovered for 4 years and artificial recovered for 5 years. In addition, vegetation conditions were investigated. The results show that:(1) The number, the coverage and the height of vegetation in sampling sites are increased along with the years of restoration; there are very few vegetation in the unrestoration grassland, its coverage is less than 10%; the number of artificial recovered for 3,4,5 years are 5,7,9 respectively; the coverage of artificial recovered for 3,4,5 years are 43.0%,51.33%,65.67% respectively; fresh grassmass ranges from 173.33 g/m2 to 430.0 g/m2, the fresh grassmass of artificial recovered for 5 years increased 148.08% and 69.75% comparing with 3 and 4 years respectively.(2) Total number of microorganism is much different among different types of grassland and it ranges from 64.23×10~3 cfu/g dry soil to 5697.09×10~3 cfu/g dry soil. The order is that artificial recovered for 5 years > artificial recovered for 4 years > artificial recovered for 3 years > unrestoration grassland, and the number of microorganism artificial recovered for 5 years is significantly higher than others.(3) Among the microorganisms, the number of bacteria is the highest (91.44% - 98.48%), then followed by actinomycetes (1.32% - 7.62%), fungi is lowest (0.2% - 1.22%). Bacteria and actinomycete account for more than 98.78% of the total.(4)Each number of bacteria, actinomycetes and fungi, all increased along with recovered years. The numbers of bacteria and fungi of recovered 5 years are much higher than other three types, the differences are very significant; the numbers of actinomycetes of recovered 5 years is significantly higher than unrestoration grassland, the difference between recovered 5 and 3 years is significant, and the difference is nonsignificant when compared with recovered 4 years.(5) Catalase activity of artificial recovered grassland for 3-5 years is higher than unrestoration grassland, the difference is significant, the order is: artificial recovered for 5 years > artificial recovered for 4 years > artificial recovered for 3 years > unrestoration grassland ; Protease activity of artificial recovered grassland for 4 and 5 years is much higher than grassland of artificial recovered for 3 years and sandy grassland, the difference is significant at 0.01 level; the difference of Invertase activity in different grassland Sampling sites is nonsignificant, there is no correlation between Invertase activity and recovered years.(6) The number of physiological groups in sandy grassland is very few, but it increased along with recovered years. The order of the number of nitrobaccter is artificial recovered for 5 years > artificial recovered for 4 years > artificial recovered for 3 years > unrestoration grassland, the same as Aero-nitrogen fixing bacteria, and the difference between each other is significant; the order of the number of denitrobacter is artificial recovered for 5 years > artificial recovered for 3 years > artificial recovered for 4 years > unrestoration grassland, and the difference between each other is significant at 0.05 level; there is no correlation between the number of Aero-cellulose decomposing bacteria and recovered years, the order is recovered for 4 years> artificial recovered for 5 years > artificial recovered for 3 years > sandy grassland, the difference between recovered 3 and 4 years is significant, but the difference between recovered 5 years and 3 or 4 years is nonsignificant.