Soil enzyme activities of typical plant communities after vegetation restoration on the Loess Plateau, China

Soil enzyme activities can indicate soil quality due to the catalyst roles enzymes play in various soil biochemical processes. However, little is known about the variations in soil enzyme activities among different plant communities with diverse environmental conditions. Here, the activities of four soil enzymes, catalase (CA), urease (UA), polyphenol oxidase (POA) and saccharase (SA), were investigated in shrub lands, forest lands and abandoned cropland on the Loess Plateau, China. Soil microbial biomass (MB) that contained bacteria, fungi and actinomycetes was also analyzed to determine the variations in enzyme activities. The results showed that soil enzyme activities varied significantly among different plant communities. Land uses, climate factors, topography and soil properties are all related to variations in enzyme activities. Specifically, soil properties including soil nutrients and MB were stable driving factors. With increasing soil MB, UA increased linearly, but CA, POA and SA increased exponentially, which might have resulted from soil nutrient deficiencies. Different plant communities with diverse microbial metabolisms performed differently in terms of soil enzyme activities, for example, in comparison to the other studied species, Hippophae rhamnoides had the greatest advantages and could improve the soil environment more effectively. Therefore, we suggest that the afforestation of Hippophae rhamnoides is an appropriate scenario for vegetation restoration in the typical hilly region of the Loess Plateau. CAcatalase activityUAurease activityPOApolyphenol oxidase activitySAsaccharase activityMBmicrobial biomassSLshrub landFLforest landACabandoned croplandMATmean annual temperatureMAPmean annual precipitationSOCsoil organic carbonTNtotal nitrogenANavailable nitrogenTPtotal phosphorousAPavailable phosphorousTKtotal potassiumAKavailable potassium