JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2024, Vol. 48 ›› Issue (3): 90-98.doi: 10.12302/j.issn.1000-2006.202211030

Special Issue: 土壤生态修复理论与技术研究

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Effects of acid rain-based transformation on Cunninghamia lanceolata fine root growth and soil nutrient content

DING Yong(), LIU Xin*(), ZHANG Jinchi, WANG Yuhao, CHEN Meiling, LI Tao, LIU Xiaowu, ZHOU Yuexiang, SUN Lianhao, LIAO Yi   

  1. Co-Innovation Center for Sustainable Forestry in Southern China, Jiangsu Provincal Key Laboratory of Soil and Water Conservation and Ecological Restoration, College of Forestry and Grassland, College of Water and Soil Conservation, Nanjing Forestry University, Nanjing 210037, China
  • Received:2022-11-26 Revised:2023-08-13 Online:2024-05-30 Published:2024-06-14

Abstract:

【Objective】 This study explored the effects of acid rain-based changes in soil nutrient content and Chinese fir (Cunninghamia lanceolata) fine root growth, to provide a theoretical basis for improving soil acidification of C. lanceolata plantations in acid rain-stressed areas.【Method】 A one-year simulated acid rain field experiment was conducted at the Tongshan Forest Farm in Nanjing, Jiangsu Province. Three acid rain acidity levels (pH=4.5, 3.5, and 2.5) were applied with each of three acid rain types: sulfuric acid rain, with 5∶1 concentration ratio of sulfur (S, SO42-) to nitrogen (N, NO3-); mixed acid rain, with 1∶1 S/N ratio; nitric acid rain, with 1∶5 S/N ratio; and a control (CK, pH=6.6, local river water). There were thus 10 total experimental treatments. Outcome measures of acid rain stress included soil chemical properties, fine root physiological characteristics, and fine root element contents. Correlations and structural equation model analyses were used to explore the direct and indirect effects of acid rain type on C. lanceolata fine root growth.【Result】 With decreasing acid rain pH and S/N ratios, the fine root biomass and root activity of C. lanceolata decreased. The catalase activity of all strong acid rain treatments (pH=2.5) was lower than that of other acid rain treatments. Compared with nitric acid rain types, the catalase activity incrementally decreased and was lower than CK; Mg and Al content, as well as the c(Ca)/c(Al) and c(Mg)/c(Al) in fine roots also differed. Compared with CK, all acid rain treatments increased fine root Ca and Al contents, while K content decreased with acid rain stress. However, there were not significant differences in soil total C, total N, C/N ratio, total S, available P, or available K among S/N ratios or pH levels. Correlation analysis showed that soil pH was extremely significant positively correlated with c(Mg)/c(Al), root biomass, and root activity (P<0.01), and that root biomass was significantly positively correlated with peroxidase, catalase, but extremely significant negative correlated with Al content (P<0.05). 【Conclusion】 After one year of experimental acid rain stress, acidity significantly impacted both soil and C. lanceolata fine roots. Acid rain type affected fine roots more strongly than it affected soil. As the S/N ratio decreased, the inhibitory effect of acid rain on C. lanceolata fine root growth was more pronounced.

Key words: Cunninghamia lanceolata, acid rain, sulfur to nitrogen ratio, fine root biomass, soil nutrient

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