ObjectiveThe dynamics of soil nutrition and stoichiometric characteristics of different successional stages during the process of natural restoration in Maolan karst forest vegetation of southwestern China were studied to explore the relationship between them, and quantitatively evaluate the degree of explanation of impact factors on soil stoichiometric characteristics, and clarify the intrinsic coupling relationship between the vegetation community succession and soil property evolution, in order to provide the theoretical basis for restoration and reconstruction of degraded karst forest.

MethodTaking he herb stage, shrub stage, arbor stage and climax stage as the research objects, three fixed sample plots were set up in each succession stage, 12 soil profiles were randomly set up according to different niche conditions and laminated sampling. The contents of SOC, TN, TP and TK were measured and the stoichiometric ratio was calculated.

ResultThe mean contents of SOC, TN, TP and TK of soil in the research region were 54.72, 4.67, 0.73 and 8.53 g/kg, respectively. There were significantly or very significantly positive correlations between the contents of SOC, TP and TN, showing relatively consistent law of change. The ratios of C:N, C:P, C:K, N:P, N:K and P:K were 11.95, 79.16, 6.50, 6.64, 0.550 1 and 0.085 2, respectively. In terms of coefficient of variation, except TK content and C:N belonged to weak variability, the soil nutrient content and stoichiometric ratio were all medium variability. With the forward succession of vegetation, the SOC, TN and TP contents in different succession stages basically increased, but the change trend of TK content was reverse V-shape, showed arbor stage > climax stage > shrub stage > herb stage. The contents of SOC, TN and TP of different soil depth at each succession stage showed that 0–10 cm was higher than 10–20 cm, but the content of TK had no obvious change. The variation trend of the soil stoichiometric characteristics with the succession was quite different. At the soil profile level, except for no significant difference between the depth of different soil layers in C:N, the others showed that 0–10 cm was higher than 10–20 cm. The results of redundancy analysis showed that soil depth and community succession were the main factors to regulate soil nutrition content and stoichiometric characteristics in the region, with the explanatory degree of 32.82% and 32.19%, respectively.

ConclusionSoil organic carbon content in the study area was relatively high, N and P contents were rich , plant growth restricted by N (or P) element may be caused by the low effectiveness of soil nutrient content.Reducing human disturbance, and appropriate protection can promote the positive succession of community, improve the stability and anti-interference of the karst forest ecosystem, and conducive to the accumulation of soil nutrients.The results preliminarily reveal the degree to which many influencing factors can explain soil nutrition content and stoichiometric characteristics, which is of important guiding significance to the protection of karst forest.