Changes of soil nutrient content, storage and stoichiometry of Phyllostachys edulis after long-term throughfall exclusion

Elucidating the response of soil nutrients to long-term drought can better predict the impact of climate change on the ecosystem of moso bamboo (Phyllostachys edulis）forest in the future, and can guide the production and management practice of bamboo forest.

This study measured and analyzed the response of soil organic carbon, total nitrogen, total phosphorus content and storage, as well as their stoichiometric characteristics, to no throughfall exclusion (CK) and long-term throughfall exclusion (DR) in bamboo forests using the “ceiling method” for rain interception.

The results showed that the average value of available phosphorus content, hydrolytic nitrogen and organic carbon content, as well as the average soil C/N and C/P values in the 0-50 cm soil layer of drought soil were significantly lower than those in the control soil (P<0.05). The total phosphorus content and average pH value of drought soil were slightly lower than those in the control, while the total nitrogen content and N/P value of soil were higher than those in the control. There was no significant difference in soil nutrient content between drought and control treatments in each soil layer of 0-10 cm, 10-30 cm, and 30-50 cm. The soil pH values in all drought soil layers were lower than those in the control, with the pH value in the 10-50 cm range being significantly lower than that of the control (P<0.05). The C/P value in the 10-30 cm drought soil layer and the C/N value in the 10-50 cm drought soil layer were significantly lower than those in the control (P<0.05), while the N/P value in the 30-50 cm soil layer was significantly higher than that in the control (P<0.05). Drought has increased the “surface aggregation” phenomenon of soil nutrient content and the chemical stoichiometry. The organic carbon storage and total phosphorus storage in the 0-50 cm soil layer under drought were lower than the control, while the total nitrogen storage in the soil was higher than the control. Relevant analysis shows that the pH value of the control soil is significantly positively correlated with organic carbon, total nitrogen, and total phosphorus storage (P<0.01), while the pH value of soil under drought stress is only significantly negatively correlated with C/N and significantly positively correlated with N/P. The total nitrogen, total phosphorus, and organic carbon content in soil under drought are significantly or extremely significantly positively correlated with N/P (P<0.05 or P<0.01), while the total phosphorus content is significantly negatively correlated with C/N (P<0.05).

The soil pH value, total phosphorus, and available phosphorus content are the main influencing factors of nitrogen and phosphorus balance in soils under drought.