Responses of terrestrial nitrogen pools and dynamics to different patterns of freeze‐thaw cycle: A meta‐analysis

• Published in: Global change biology Vol. 24; no. 6; pp. 2377 - 2389
• Main Authors: Gao, Decai, Zhang, Lei, Liu, Jun, Peng, Bo, Fan, Zhenzhen, Dai, Weiwei, Jiang, Ping, Bai, Edith
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.06.2018
• Subjects: Acclimation; Acclimatization; Agricultural land; Alpine environments; Biomass; Climate change; Cycles; denitrification; Duration; Dynamics; Ecosystems; Emissions; Environmental changes; Fluxes; Freeze-thawing; freeze‐thaw cycle; Freezing; Global Warming; Leaching; Meta-analysis; microbial biomass; Microorganisms; Mineral nutrients; Mineralization; N fluxes; N2O; Nitrification; Nitrogen; Nitrogen - chemistry; Nitrogen - metabolism; Nitrogen Cycle; Nitrous oxide; Polar environments; Pools; Soil; Soil treatment; Soils; Temperature; Terrestrial ecosystems; Terrestrial environments; Tundra; mineralization; N fluxes; freeze-thaw cycle; nitrification; microbial biomass; N2O; denitrification
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.14010

Altered freeze‐thaw cycle (FTC) patterns due to global climate change may affect nitrogen (N) cycling in terrestrial ecosystems. However, the general responses of soil N pools and fluxes to different FTC patterns are still poorly understood. Here, we compiled data of 1519 observations from 63 studies and conducted a meta‐analysis of the responses of 17 variables involved in terrestrial N pools and fluxes to FTC. Results showed that under FTC treatment, soil NH4+, NO3−, NO3− leaching, and N2O emission significantly increased by 18.5%, 18.3%, 66.9%, and 144.9%, respectively; and soil total N (TN) and microbial biomass N (MBN) significantly decreased by 26.2% and 4.7%, respectively; while net N mineralization or nitrification rates did not change. Temperate and cropland ecosystems with relatively high soil nutrient contents were more responsive to FTC than alpine and arctic tundra ecosystems with rapid microbial acclimation. Therefore, altered FTC patterns (such as increased duration of FTC, temperature of freeze, amplitude of freeze, and frequency of FTC) due to global climate warming would enhance the release of inorganic N and the losses of N via leaching and N2O emissions. Results of this meta‐analysis help better understand the responses of N cycling to FTC and the relationships between FTC patterns and N pools and N fluxes. 1. Freeze‐thaw cycle significantly increased inorganic N, NO3− leaching, and N2O emission, but significantly decreased soil total N and microbial biomass nitrogen. 2. Temperate and cropland ecosystems with relatively high soil nutrient contents were more responsive to FTC than alpine and arctic tundra ecosystems with rapid microbial acclimation. 3. Altered FTC patterns (such as increased duration of FTC, temperature of freeze, amplitude of freeze, and frequency of FTC) due to global climate warming would enhance the release of inorganic N and the losses of N via leaching and N2O emissions.