Abstract:Soil enzymes actively participate in the biochemical processes of soil systems and are the key link to the "plant-soil enzymes-soil nutrients". In order to investigate the effects of vegetation types on soil nutrient and enzymes activities in the hilly region of the Loess Plateau, four typical vegetations (grassland, Xanthoceras sorbifolia, Caragana korshinskii shrub, and Hippophae rhamnoides) in the loess hilly region were studied. Soil samples of 0-10, 10-20 and 20-40 cm layers were sampled to determine and analyze the changes of soil nutrient (carbon, nitrogen, phosphorus) and soil enzymes activities (sucrose, urease, catalase, amylase). The results showed that the soil organic carbon and total nitrogen contents in the 0-40 cm layer of the Xanthoceras sorbifolia were 19.42% and 35.15%, 82.98% and 40.49%, 67.27% and 24.12% higher than those of the grassland, Caragana korshinskii shrub, and Hippophae rhamnoides respectively. With the increase of soil depth, the contents of soil organic carbon, total nitrogen and total phosphorus showed a "increase first and then decrease" change in Caragana korshinskii shrub, but gradually decreased under the other three vegetation types. The soil amylase, urease and sucrase activities were significantly different among the four vegetation types (P<0.05), and the soil enzymes activities decreased with the increase of soil depth. The maximum value of soil amylase was found in the grassland, the maximum values of urease and sucrase activities were in Xanthoceras sorbifolia, and the lowest values of the three enzymes were found in Caragana korshinskii shrub. Correlation analysis showed that soil organic carbon contents were significantly positively correlated with total nitrogen, sucrase and urease activities (P<0.01). There was a significant positive correlation between soil total nitrogen contents and urease activities at 0.01 level, and a significant positive correlation between total phosphorus contents and sucrose activities at 0.05 level. Soil total phosphorus contents were negatively correlated with nitrate nitrogen contents (P<0.01), positively correlated with sucrose (P<0.01) and amylase activities (P<0.05). Therefore, vegetation type is an important factor affecting soil enzymes activities and nutrient changes in the Loess Plateau.