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<p>Recent increases in nitrogen and phosphorus deposition are altering the rates of soil carbon release at unprecedented levels. However, the specific drivers of soil respiration under nitrogen and phosphorus additions remain poorly understood. To address this gap, we conducted a two-year experiment examining the response of various soil respiration components to nitrogen and phosphorus additions within <i>Pinus massoniana</i> plantations.&#xa0;We established six experimental plots with varying treatment gradients: control, phosphorus only, low nitrogen, low nitrogen and phosphorus, high nitrogen, high nitrogen and phosphorus in July 2022. We measured and calculated multiple variables including soil respiration rates and temperature sensitivity (<i>Q</i><sub><i>10</i></sub>), soil chemical properties (including pH and nutrients), soil microbial biomass and enzyme activity, soil arthropod diversity characteristics (biomass and community composition), and litter characteristics (including biomass and nutrients). We assessed differences in these indicators across treatments, linear relationships analyzed between soil respiration rates and each indicator and developed a path model to elucidate the effects of nitrogen and phosphorus addition on soil respiration.&#xa0;(1) The addition of nitrogen and phosphorus significantly reduced the rates of various soil respiration components in <i>Pinus massoniana</i> plantations (<i>P</i> &lt; 0.05), yet they did not significantly impact the overall <i>Q</i><sub><i>10</i></sub> values (<i>P</i> ≥ 0.05); (2) The 2-year application of nitrogen and phosphorus led to a significant decrease in pH, significantly affecting arthropod community characteristics, litter biomass and nutrient content, soil microbial biomass, and soil enzyme activity (<i>P</i> &lt; 0.05); (3) Nitrogen and phosphorus addition significantly affected soil respiration through 4 pathways (Goodness-of-fit, GOF = 0.755): soil nutrients-pH-microbial biomass and enzyme activity pathway; soil nutrients-litter-microbial biomass and enzyme activity pathway; soil nutrients-litter pathway; and soil nutrients-arthropods-microbial biomass and enzyme activity pathway.&#xa0;Under the short-term nitrogen and phosphorus addition scenario, the enrichment of soil nutrients led to a decrease in soil pH, which negatively affected litter characteristics, arthropod community traits, soil microbial biomass and enzyme activity, ultimately inhibiting soil respiration. In the future, we will conduct longer-term nitrogen and phosphorus addition experiments and continuous respiration monitoring to further explore the long-term response of soil respiration to nutrient inputs.</p>

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Nitrogen and Phosphorus Additions Suppress Soil Respiration in Pinus Massoniana Plantations: Integrated Effects of Soil Chemistry, Microbial, Arthropod, and Litter on Carbon Release

  • 期刊论文

  • 发表日期：

    2025年10月21日

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  • Jing Li,
  • Ruimei Cheng,
  • Meng Zhang,
  • Yongwei Zhou,
  • Tian Chen,
  • Yafei Shen,
  • Lixiong Zeng,
  • Changfu Liu,
  • Wenfa Xiao

摘要

Recent increases in nitrogen and phosphorus deposition are altering the rates of soil carbon release at unprecedented levels. However, the specific drivers of soil respiration under nitrogen and phosphorus additions remain poorly understood. To address this gap, we conducted a two-year experiment examining the response of various soil respiration components to nitrogen and phosphorus additions within Pinus massoniana plantations. We established six experimental plots with varying treatment gradients: control, phosphorus only, low nitrogen, low nitrogen and phosphorus, high nitrogen, high nitrogen and phosphorus in July 2022. We measured and calculated multiple variables including soil respiration rates and temperature sensitivity (Q10), soil chemical properties (including pH and nutrients), soil microbial biomass and enzyme activity, soil arthropod diversity characteristics (biomass and community composition), and litter characteristics (including biomass and nutrients). We assessed differences in these indicators across treatments, linear relationships analyzed between soil respiration rates and each indicator and developed a path model to elucidate the effects of nitrogen and phosphorus addition on soil respiration. (1) The addition of nitrogen and phosphorus significantly reduced the rates of various soil respiration components in Pinus massoniana plantations (P < 0.05), yet they did not significantly impact the overall Q10 values (P ≥ 0.05); (2) The 2-year application of nitrogen and phosphorus led to a significant decrease in pH, significantly affecting arthropod community characteristics, litter biomass and nutrient content, soil microbial biomass, and soil enzyme activity (P < 0.05); (3) Nitrogen and phosphorus addition significantly affected soil respiration through 4 pathways (Goodness-of-fit, GOF = 0.755): soil nutrients-pH-microbial biomass and enzyme activity pathway; soil nutrients-litter-microbial biomass and enzyme activity pathway; soil nutrients-litter pathway; and soil nutrients-arthropods-microbial biomass and enzyme activity pathway. Under the short-term nitrogen and phosphorus addition scenario, the enrichment of soil nutrients led to a decrease in soil pH, which negatively affected litter characteristics, arthropod community traits, soil microbial biomass and enzyme activity, ultimately inhibiting soil respiration. In the future, we will conduct longer-term nitrogen and phosphorus addition experiments and continuous respiration monitoring to further explore the long-term response of soil respiration to nutrient inputs.