3 adjacent typical collapse mounds (Ⅰ

Ⅱ and Ⅲ) were selected in Huangniken collapse mound group in Zhuotian Town

Changting County of southwestern Fujian Province

in which vegetation coverage of each collapse mound was 2%

20% and 95%

respectively; seven plots including upper catchment

collapsing wall (top

middle and bottom part)

colluvial deposit (upper and lower part) and channel outlet for each collapse mound were sampled

and the main physical and chemical properties including particle composition

bulk density

water content

pH value

soil organic carbon (SOC)

total nitrogen (TN)

total phosphorus (TP) and total potassium (TK) in 3 depths (0—10 cm

10—20 cm and 20—30 cm) of each plot were measured. Meanwhile

spatial variation of the contents of SOC

TN

TP

TK and their stoichiometric characteristics in each collapse mound with different depth and position were analyzed in this paper. The results indicated that with improvement of vegetation coverage (fromⅠto Ⅲ)

the contents of SOC

TN

TP

TK and their stoichiometric ratios increased significantly with the exception of TP content and P/K

and the order of increasing range of soil nutrients was SOC＞TN＞TK＞TP

while that of soil stoichiometric ratios was C/P＞C/K＞C/N＞N/K＞N/P＞P/K. Under different depth (from 0—10 cm to 20—30 cm)

the contents of SOC

TN

TK and the ratios of C/N

C/P

C/K and N/P generally decreased

while the content of TP and the ratios of N/K and P/K basically remained stable. Variation of soil nutrient contents and their stoichiometric ratios for different position were greatly obvious in each collapsing hill: the contents of SOC

TN

TK

C/N and C/P

C/K

N/P and N/K showed a down-up-down variation tendency along the runoff routes from upper catchment to channel outlet via collapsing wall and colluvial deposit

while TP content and P/K ratio kept relatively consistent. Besides

soil stoichiometry was closely related to nutrient content

silt content

bulk density

water content and pH value by stepwise regression analysis. In summary

the contents of C

N and P were at very low level

especially P content in the severely eroded context of collapse mound.