Browsing by Author "Ren, Tianjing"

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    Asymmetric responses of soil dissolved organic carbon and dissolved organic nitrogen to warming: A meta-analysis
    (Elsevier, 2025-02-25) Ren, Tianjing; Smreczak, Bożena; Ukalska-Jaruga, Aleksandra; Hassan, Waseem; Cai, Andong
    Soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) play pivotal roles in regulating soil carbon and nitrogen cycles. The global effects of experimental warming on DOC and DON concentrations and their relationship (DOC:DON) remain uncertain. This study integrates a dataset containing 321 separate DOC and 187 DON independent experiments to address the magnitude and direction of warming’s impact on DOC and DON, as well as the key driving factors. Our results indicated that while warming did not significantly affect DOC concentrations, it led to a notable increase in DON concentrations (8.84%), consequently reducing DOC:DON ratio by 10.79%. Soil moisture emerged as the most influential factor (19.0%) driving DOC responses to warming, whereas soil nitrate nitrogen was the primary driver (33.2%) of DON responses to warming. Soil ammonium nitrogen exhibited a positive linear relationship with the DOC:DON ratio, while soil nitrate nitrogen responded negatively as the DOC:DON ratio increased. Our results revealed the complex responses of carbon and nitrogen cycles to warming, including their decoupling patterns. This finding highlights the sensitivity and adaptability of soil carbon and nitrogen cycles to experimental warming, uncovers that warming could disrupt the soil carbon and nitrogen balance, potentially affecting ecosystem stability and function.
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    Differential impacts of nitrogen addition on soil dissolved organic carbon in humid and non-humid regions: A global meta-analysis
    (Elsevier, 2025-03-01) Ren, Tianjing; Smreczak, Bożena; Ukalska-Jaruga, Aleksandra; Li, Xiaojie; Hassa, Wassem; Cai, Andong
    Soil dissolved organic carbon (DOC) is the most active carbon pool, providing essential carbon and energy to soil microorganisms while playing a crucial role in carbon sequestration, transport, and stabilization in soils. Nitrogen (N) addition, a key factor influencing terrestrial carbon cycling, can significantly alter soil DOC dynamics. However, the global patterns and underlying drivers of DOC responses to N addition, particularly across regions with varying aridity indices, remain unclear. This study analyzed 1132 paired observations from 103 independent studies to quantify the response pattern of DOC to N addition in humid (554 observations) and non-humid (574 observations) regions and identify the factors driving these effects. The findings revealed an asymmetrical effect of N addition on soil DOC between humid and non-humid regions, rather than on microbial biomass carbon (MBC) or soil organic carbon (SOC). Specifically, N addition significantly decreased soil DOC (􀀀 2.49%) in humid regions, while it increased DOC (7.30%) in non-humid regions. The effect size of soil DOC decreased linearly with the ratio of MBC to SOC in humid regions but increased linearly in non-humid regions. In humid regions, soil DOC response was positively correlated with initial MBC and inversely correlated with initial soil pH, whereas the opposite trend was observed in non-humid regions. Seasonal precipitation variability was identified as a significant driver of soil DOC response, independent of temperature, soil properties, and N addition rates. Moreover, initial SOC content was the primary driving factor for soil DOC response in humid regions, while the N addition rates were the primary driver in non-humid regions. These findings have important implications for enhancing soil carbon pool management, improving global carbon models, and addressing climate change, particularly under varying climatic conditions.