Abstract:

Objective: This study is aimed to investigate the characteristics of changes of soil nutrients and stoichiometrict ratio during the expansion of moso bamboo (Phyllostachys edulis) forest, in order to provide a theoretical basis for the regulation of expansion of moso bamboo forest. Method: Three 10 m×50 m sample transects each with 3 sample plots were set up along the extension direction of moso bamboo forest in Yongan Long-Term Ecological Observation Station for Bamboo Forest in Fujian Province. The characteristics of soil nutrients and stoichiometric ratios at different expansion stages(along the expansion direction in order: early expansion, middle expansion, and late expansion) were analyzed, in order to reveal the patterns of impacts on soil nutrients by the expansion of moso bamboo. Result: During the expansion of moso bamboo to abandoned land, the variation coefficients of soil nutrients and stoichiometric ratios in 0-30 cm soil layer was as follows: late expansion stage (13.8%-51.3%) > middle expansion stage (8.3%-31.8%) > early expansion stage (4.3%-29.8%). The variation range of variation coefficient of C and N contents (26.7%-43.8%) was larger than the contents of P and K (4.3%-24.1%). With the expansion of moso bamboo to abandoned land, the contents of C and N increased significantly and P decreased significantly. In 0-20 cm soil layer, the contents of C and N of the later stage of expansion was significantly higher than that of the earlier and middle stages of expansion (P < 0.05). In 20-30 cm soil layer, there was no significant difference for the contents of C and N among different expansion stages (P> 0.05);but the content of P decreased significantly with the expansion of Phyllostachys pubescens (P < 0.05). In 0-30 cm soil layer, C:N was relatively stable, and there was no significant difference between different expansion stages. C:P and N:P of the later stage of expansion were significantly larger than that of the earlier stage, but there was no significant difference between the earlier stage and the middle stage of expansion (P> 0.05). In 0-30 cm soil layer, there was a significant positive correlation between C and N (P < 0.01); C and N were negatively correlated with K(P < 0.01), but no significant correlation with P. C:N was significantly correlated with C:P, but not with N:P. Conclusion: With the expansion of moso bamboo, the contents of soil C and N in 0-20 cm soil layer increased significantly(P < 0.05), while the content of soil P decreased significantly(P < 0.05). In 0-30 cm soil layer, the content of K did not change significantly at different expansion stages. C:P and N:P at the late stage of expansion were significantly higher than those at the early stage, but N:P was still lower than the average levels of China and the world, and the contents of N and P could not meet the demand of moso bamboo forests. Soil nutrient content of moso bamboo forest increased at the later stage of expansion, but its effectiveness decreased, which was not conducive to the healthy and stable development of moso bamboo forest. In order to maintain the healthy growth of moso bamboo forests, it is necessary to regulate and supplement N and P elements in time.

Key words: moso bamboo expansion, abandoned land, soil nutrien, stoichiometry