title: Photosynthetic and growth responses of Schima superba seedlings to sulfuric and nitric acid depositions.
abstract: A continuing rise in acid deposition can cause forest degradation. In China, acid deposition has converted gradually from sulfuric acid deposition (SAD) to nitric acid deposition (NAD). However, the differing responses of photosynthesis and growth to depositions of sulfuric vs. nitric acid have not been well studied. In this study, 1-year-old seedlings of Schima superba, a dominant species in subtropical forests, were treated with two types of acid deposition SO4 (2-)/NO3 (-) ratios (8:1 and 0.7:1) with two applications (foliar spraying and soil drenching) at two pH levels (pH 3.5 and pH 2.5) over a period of 18 months. The results showed that the intensity, acid deposition type, and spraying method had significant effects on the physiological characteristics and growth performance of seedlings. Acid deposition at pH 2.5 via foliar application reduced photosynthesis and growth of S. superba, especially in the first year. Unlike SAD, NAD with high acidity potentially alleviated the negative effects of acidity on physiological properties and growth, probably due to a fertilization effect that improved foliar nitrogen and chlorophyll contents. Our results suggest that trees were damaged mainly by direct acid stress in the short term, whereas in the long term, soil acidification was also likely to be a major risk to forest ecosystems. Our data suggest that the shift in acid deposition type may complicate the ongoing challenge of anthropogenic acid deposition to ecosystem stability.
authors.affiliation: School of Ecological and Environmental Science, East China Normal University, 200241, Shanghai, China.|Tiantong National Forest Ecosystem Observation and Research Station, 315114, Ningbo, Zhejiang, China.
authors.forename: Fang-Fang
authors.initials: FF
authors.lastname: Yao
authors.affiliation: School of Ecological and Environmental Science, East China Normal University, 200241, Shanghai, China.
authors.forename: Hui-Ming
authors.initials: HM
authors.lastname: Ding
authors.affiliation: School of Ecological and Environmental Science, East China Normal University, 200241, Shanghai, China.
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Feng
authors.affiliation: School of Ecological and Environmental Science, East China Normal University, 200241, Shanghai, China.
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: School of Ecological and Environmental Science, East China Normal University, 200241, Shanghai, China.
authors.forename: Song-Yu
authors.initials: SY
authors.lastname: Yang
authors.affiliation: School of Ecological and Environmental Science, East China Normal University, 200241, Shanghai, China. xhwang@des.ecnu.edu.cn.|Tiantong National Forest Ecosystem Observation and Research Station, 315114, Ningbo, Zhejiang, China. xhwang@des.ecnu.edu.cn.
authors.forename: Xi-Hua
authors.initials: XH
authors.lastname: Wang
mesh_terms: D002681:China; D002734:Chlorophyll / Q000378:metabolism; D017753:Ecosystem; D065928:Forests; D017942:Nitric Acid / Q000633:toxicity*; D009584:Nitrogen / Q000032:analysis; D010788:Photosynthesis / Q000187:drug effects*; D036226:Seedlings / Q000378:metabolism / Q000502:physiology*; D012987:Soil / Q000737:chemistry; D013464:Sulfuric Acids / Q000633:toxicity*; D064028:Tracheophyta / Q000187:drug effects / Q000502:physiology*; D014197:Trees / Q000378:metabolism
chemical_list: D012987:Soil; D013464:Sulfuric Acids; D002734:Chlorophyll; D017942:Nitric Acid; D009584:Nitrogen; C033158:sulfuric acid
keywords: Foliar application; Growth; Photosynthetic properties; Soil drench; Sulfuric and nitric acid depositions