Comparative effects of simulated acid rain of different ratios of SO42- to NO3- on fine root in subtropical plantation of China

Xin Liu; Wenrui Zhao; Miaojing Meng; Zhiyuan Fu; Linhao Xu; Yan Zha; Jianmin Yue; Shuifeng Zhang; Jinchi Zhang

doi:10.1016/j.scitotenv.2017.11.073

Comparative effects of simulated acid rain of different ratios of SO₄^2- to NO₃^- on fine root in subtropical plantation of China

Sci Total Environ. 2018 Mar 15:618:336-346. doi: 10.1016/j.scitotenv.2017.11.073. Epub 2017 Nov 10.

Authors

Xin Liu¹, Wenrui Zhao¹, Miaojing Meng¹, Zhiyuan Fu¹, Linhao Xu¹, Yan Zha², Jianmin Yue¹, Shuifeng Zhang³, Jinchi Zhang⁴

Affiliations

¹ Co-Innovation Center for Sustainable Forestry in Southern China, Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration, Nanjing Forestry University, 159 Longpan Road, Nanjing, Jiangsu 210037, China.
² Jiangsu Province Key Laboratory of Ecological Engineering, Nanjing Forestry University, Nanjing 210037, China.
³ Co-Innovation Center for Sustainable Forestry in Southern China, Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration, Nanjing Forestry University, 159 Longpan Road, Nanjing, Jiangsu 210037, China; Nanjing Forest Police College, Nanjing, Jiangsu 210023, China.
⁴ Co-Innovation Center for Sustainable Forestry in Southern China, Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration, Nanjing Forestry University, 159 Longpan Road, Nanjing, Jiangsu 210037, China. Electronic address: zhang8811@njfu.edu.cn.

PMID: 29132001
DOI: 10.1016/j.scitotenv.2017.11.073

Abstract

The influence of acid rain on forest trees includes direct effects on foliage as well as indirect soil-mediated effects that cause a reduction in fine-root growth. In addition, the concentration of NO₃^- in acid rain increases with the rapidly growing of nitrogen deposition. In this study, we investigated the impact of simulated acid rain with different SO₄^2-/NO₃^- (S/N) ratios, which were 5:1 (S), 1:1 (SN) and 1:5 (N), on fine-root growth from March 2015 to February 2016. Results showed that fine roots were more sensitive to the effects of acid rain than soils in the short-term. Both soil pH and fine root biomass (FRB) significantly decreased as acid rain pH decreased, and also decreased with the percentage of NO₃^- increased in acid rain. Acid rain pH significantly influenced soil total carbon and available potassium in summer. Higher acidity level (pH=2.5), especially of the N treatments, had the strongest inhibitory impact on soil microbial activity after summer. The structural equation modelling results showed that acid rain S/N ratio and pH had stronger direct effects on FRB than indirect effects via changed soil and fine root properties. Fine-root element contents and antioxidant enzymes activities were significantly affected by acid rain S/N ratio and pH during most seasons. Fine-root Al ion content, Ca/Al, Mg/Al ratios and catalase activity were used as better indicators than soil parameters for evaluating the effects of different acid rain S/N ratios and pH on forests. Our results suggest that the ratio of SO₄^2- to NO₃^- in acid rain is an important factor which could affect fine-root growth in subtropical forests of China.

Keywords: Acid rain; Fine root biomass; Fine root element; SO(4)(2−)/NO(3)(−); Soil acidification.