Abstract:

To understand the spatial variability of soil C， N and P contents and their stoichiometric ratios in the hilly area of Lanzhou on the north bank of the Yellow River Basin. Based on 12 sample plots， we measured soil water content （SWC）， pH， soil organic carbon （SOC）， total nitrogen （STN） and total phosphorus （STP） at a depth of 1m in 12 plots. Then， we had analyzed the difference of SOC， STN and STP contents and their eco-stoichiometry characteristics in the study area in terms of different vegetation and soil layers， as well as their spatial variability. Results show that： （1） The mean values of SOC， STN and STP in the study area were 4.53， 0.74 and 0.13 g·kg^-1， respectively. The mean values of C∶N， C∶P and N∶P were 7.85， 55.17 and 8.40， respectively. （2） The ratios of nugget to soil C₀/（C₀+C）<0.25 of SOC， STN， C∶N and N∶P are influenced by natural factors such as climate， vegetation and topography in study area. The C₀/（C₀+C）>0.75 of STP and C∶P are influenced by anthropogenic factors likely fallowing and grassland restoration. （3） The study area is the most deficient in organic carbon and is limited by nitrogen， while phosphorus will not be a limiting factor in the short term. These results suggest that people should pay attention to the allocation and application of organic and nitrogen fertilizers in the subsequent ecological management and restoration activities， at the same time， people need to reduce human disturbance. All of this will be important for the rapid recovery of vegetation and fixation of soil nutrient in the hilly area of Lanzhou on the north bank of the Yellow River Basin.

Key words: Lanzhou section of the Yellow River, soil nutrient, stoichiometry, spatial variation