Different responses of asymbiotic nitrogen fixation to nitrogen addition between disturbed and rehabilitated subtropical forests

Mianhai Zheng, Wei Zhang, Yiqi Luo, Taiki Mori, Qinggong Mao, Senhao Wang, Juan Huang, Xiankai Lu, Jiangming Mo

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Asymbiotic nitrogen (N) fixation is an important source of new N in ecosystems, and is sensitive to atmospheric N deposition. However, there is limited understanding of asymbiotic N fixation and its response to N deposition in the context of forest rehabilitation. In this study, we measured N fixation rates (acetylene reduction) in different ecosystem compartments (i.e. soil, forest floor, moss Syrrhopodon armatus, and canopy leaves) in a disturbed and a rehabilitated subtropical forest in southern China, under 12 years of N treatments: control, low N addition (50 kg N ha− 1 yr− 1), and medium N addition (100 kg N ha− 1 yr− 1). The rehabilitated forest had higher nutrient (e.g. N) availability than the disturbed forest. In control plots, N fixation rates in forest floor were higher in the rehabilitated forest than in the disturbed forest, but N fixation rates in other compartments (soil, S. armatus, and canopy leaves) were comparable between the forests. Nitrogen addition significantly suppressed N fixation in soil, forest floor, S. armatus, and canopy leaves in the disturbed forest, but had no significant effect on those compartments in the rehabilitated forest. The main reasons for the negative effects of N addition on N fixation in the disturbed forest were NH4 + inhibition (soil), the P and C limitation (forest floor), and the reduced N dependence on canopy N-fixers (S. armatus and canopy leaves). We conclude that asymbiotic N fixation does not decline with increasing N availability after rehabilitation in the study forests. The inhibitory effects of N addition on asymbiotic N fixation occurred in the disturbed forest but not in the rehabilitated forest, indicating that forest rehabilitation may change the response of ecosystem function (i.e. N fixation) to N deposition, which merits further study in other tropical and subtropical regions.

Original languageEnglish (US)
Pages (from-to)1505-1512
Number of pages8
JournalScience of the Total Environment
Volume601-602
DOIs
StatePublished - Dec 1 2017
Externally publishedYes

Keywords

  • Acetylene reduction
  • Asymbiotic nitrogen fixation
  • Disturbed forest
  • Nitrogen addition
  • Rehabilitated forest

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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