In order to provide the basis for ecological construction in the area of grassland

we studied the effects of enclosure and level trench ecological restoration on soil biological characteristics in the Hilly Loess Plateau Gully steppe. Using the method of space gradient instead of time gradient

in typical steppe in the loess hilly area of Ningxia

we selected soils in areas which included the unenclosed (grazing)

enclosed for 3-15 years

the level trench after 1-15 years

analyzed the change characteristics and relationship of the number of microorganisms

soil microbial biomass nitrogen and carbon

and soil enzyme activity the in 0-10 cm

10-20 cm

20-30 cm

and 30-40 cm soil layers. The results showed that: (1) Soil microbial community in the test area was dominated by actinomycetes

which accounted for 86.18-94.43%

and the overall order was actinomycetes > bacteria > fungi; the amount of soil microorganisms

the number of bacteria and actinomycetes

microbial biomass carbon and nitrogen

urease

protease

phosphatase

sucrase activity all showed an upward change with the increase of enclosure ages

but they all showed an up-down-up trend in level trench; on the contrary

the change of soil catalase activity had a opposite trend in both the enclosure and level trench

and the number of fungi was lower in FY6 and SP6

being 11.33 cfu/g and 4.67 cfu/g

respectively. (2) Under different treatments

in the 0-40 cm soil layer

microbial and enzyme activity in the upper soil was higher than in the underlying soil. The correlations between soil microorganism

enzyme activity and contents organic matter and main nutrients were significant (p < 0.05); (3) Within the similar recovery period

the number of soil microorganisms

microbial biomass carbon and nitrogen

and enzyme activity were generally higher in the enclosed grassland (p < 0.05). Our research showed that

compared with level trench

enclosure was more conducive to increase soil microorganisms and enzyme activities in typical steppe of the Loess Hilly Area.