Global soil nitrogen cycle pattern and nitrogen enrichment effects: Tropical versus subtropical forests

Ahmed S. Elrys, Qi Lin Zhu, Chunlan Jiang, Juan Liu, Hamida H.H. Sobhy, Qunli Shen, Yves Uwiragiye, Yanzheng Wu, Khaled A. El-Tarabily, Lei Meng, Christoph Müller, Jinbo Zhang

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Tropical and subtropical forest biomes are a main hotspot for the global nitrogen (N) cycle. Yet, our understanding of global soil N cycle patterns and drivers and their response to N deposition in these biomes remains elusive. By a meta-analysis of 2426-single and 161-paired observations from 89 published 15 N pool dilution and tracing studies, we found that gross N mineralization (GNM), immobilization of ammonium ((Formula presented.)) and nitrate ((Formula presented.)), and dissimilatory nitrate reduction to ammonium (DNRA) were significantly higher in tropical forests than in subtropical forests. Soil N cycle was conservative in tropical forests with ratios of gross nitrification (GN) to (Formula presented.) (GN/ (Formula presented.)) and of soil nitrate to ammonium (NO3/NH4+) less than one, but was leaky in subtropical forests with GN/ (Formula presented.) and NO3/NH4+ higher than one. Soil NH4+ dynamics were mainly controlled by soil substrate (e.g., total N), but climatic factors (e.g., precipitation and/or temperature) were more important in controlling soil NO3 dynamics. Soil texture played a role, as GNM and (Formula presented.) were positively correlated with silt and clay contents, while (Formula presented.) and DNRA were positively correlated with sand and clay contents, respectively. The soil N cycle was more sensitive to N deposition in tropical forests than in subtropical forests. Nitrogen deposition leads to a leaky N cycle in tropical forests, as evidenced by the increase in GN/ (Formula presented.), NO3/NH4+, and nitrous oxide emissions and the decrease in (Formula presented.) and DNRA, mainly due to the decrease in soil microbial biomass and pH. Dominant tree species can also influence soil N cycle pattern, which has changed from conservative in deciduous forests to leaky in coniferous forests. We provide global evidence that tropical, but not subtropical, forests are characterized by soil N dynamics sustaining N availability and that N deposition inhibits soil N retention and stimulates N losses in these biomes.

Original languageEnglish
Pages (from-to)1905-1921
Number of pages17
JournalGlobal Change Biology
Volume29
Issue number7
DOIs
Publication statusPublished - Apr 2023

Keywords

  • global change
  • leaky or conservative nitrogen cycle
  • nitrogen cycle
  • nitrogen deposition scenarios
  • nitrogen loss
  • tropical and subtropical forests

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • General Environmental Science

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