Journal article

Publication year: 2023

Pages: 1905-1921

Journal: Global Change Biology

Volume number: 29

Issue number: 7

ISSN: 1354-1013

eISSN: 1365-2486

DOI Link: https://doi.org/10.1111/gcb.16603

Publisher: Wiley

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 (INH4) and nitrate (INO3), 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 INH4 (GN/INH4) and of soil nitrate to ammonium (NO3−/NH 4+) less than one, but was leaky in subtropical forests with GN/INH4 and NO3−/NH 4+ 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 INH4 were positively correlated with silt and clay contents, while INO3 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/INH4, NO3−/NH 4+, and nitrous oxide emissions and the decrease in INO3 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.

Harvard Citation style: Elrys, A., Zhu, Q., Jiang, C., Liu, J., Sobhy, H., Shen, Q., et al. (2023) Global soil nitrogen cycle pattern and nitrogen enrichment effects: Tropical versus subtropical forests, Global Change Biology, 29(7), pp. 1905-1921. https://doi.org/10.1111/gcb.16603

APA Citation style: Elrys, A., Zhu, Q., Jiang, C., Liu, J., Sobhy, H., Shen, Q., Uwiragiye, Y., Wu, Y., El-Tarabily, K., Meng, L., Müller, C., & Zhang, J. (2023). Global soil nitrogen cycle pattern and nitrogen enrichment effects: Tropical versus subtropical forests. Global Change Biology. 29(7), 1905-1921. https://doi.org/10.1111/gcb.16603