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<p>The temperature sensitivity (Q<sub>10</sub>) of soil microbial respiration (<i>Rs</i>) is a critical parameter for predicting the response of microbially mediated decomposition of global soil organic carbon (SOC) to climate change. However, the variations in Q<sub>10</sub> across horizontal and vertical spatial gradients remain contentious. In this study, we conducted a simulated soil warming incubation experiment across temperature gradients of 5&#xa0;°C, 15&#xa0;°C, 25&#xa0;°C, and 35&#xa0;°C using soils collected from the southern subtropical forest (SSF), mid-subtropical forest (MSF) and temperate forest (TF) in China. Soil samples were obtained from four depth intervals along a 60&#xa0;cm soil profile: 0–15&#xa0;cm, 15–30&#xa0;cm, 30–45&#xa0;cm, and 45–60&#xa0;cm. We measured soil microbial respiration, SOC fractions, soil chemical properties, microbial community structure and activity. Q<sub>10</sub> values were calculated, and the underlying mechanistic relationships among these variables were examined. Significant spatial variations in Q<sub>10</sub> were observed (<i>P</i> &lt; 0.05): (1) in the 30–60&#xa0;cm soil layers, Q<sub>10</sub> values in TF were significantly higher than those in SSF and MSF; (2) with in SSF, Q<sub>10</sub> in the topsoil (0–15&#xa0;cm) was markedly greater than that in the deep soil (45–60&#xa0;cm). Horizontally, the higher Q<sub>10</sub> values in TF appear to be influenced with higher-quality carbon substrates, a greater abundance of <i>K</i>-strategies microbial taxa, higher microbial activity and prolonged exposure to low temperatures. Vertically, in the SSF, the higher Q<sub>10</sub> in topsoil was primarily attributed to higher SOC content, the presence of more labile carbon substrates and enhanced microbial activity. These findings underscore the important roles of carbon quality, microbial life-history strategies (<i>K</i>-strategies) and microbial activity in mediating the Q<sub>10</sub> of <i>Rs</i>, especially in deep soils which are easily ignored. Based on these findings, it can be predicted that under global warming scenarios, temperate forests may experience accelerated SOC decomposition at horizontal spatial scales, especially in deeper soil layers. In subtropical forests, topsoil may exhibit more rapid carbon loss along vertical gradients.</p> Graphical abstract <p></p>

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Higher carbon quality, microbial K-strategies and activity raise temperature sensitivity of soil carbon decomposition in forest soils

  • 期刊论文

  • 发表日期：

    2026年5月13日

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  • Kuan Liang,
  • Yuandong Cheng,
  • Xue Wang,
  • Fangchao Wang,
  • Fusheng Chen

摘要

The temperature sensitivity (Q10) of soil microbial respiration (Rs) is a critical parameter for predicting the response of microbially mediated decomposition of global soil organic carbon (SOC) to climate change. However, the variations in Q10 across horizontal and vertical spatial gradients remain contentious. In this study, we conducted a simulated soil warming incubation experiment across temperature gradients of 5 °C, 15 °C, 25 °C, and 35 °C using soils collected from the southern subtropical forest (SSF), mid-subtropical forest (MSF) and temperate forest (TF) in China. Soil samples were obtained from four depth intervals along a 60 cm soil profile: 0–15 cm, 15–30 cm, 30–45 cm, and 45–60 cm. We measured soil microbial respiration, SOC fractions, soil chemical properties, microbial community structure and activity. Q10 values were calculated, and the underlying mechanistic relationships among these variables were examined. Significant spatial variations in Q10 were observed (P < 0.05): (1) in the 30–60 cm soil layers, Q10 values in TF were significantly higher than those in SSF and MSF; (2) with in SSF, Q10 in the topsoil (0–15 cm) was markedly greater than that in the deep soil (45–60 cm). Horizontally, the higher Q10 values in TF appear to be influenced with higher-quality carbon substrates, a greater abundance of K-strategies microbial taxa, higher microbial activity and prolonged exposure to low temperatures. Vertically, in the SSF, the higher Q10 in topsoil was primarily attributed to higher SOC content, the presence of more labile carbon substrates and enhanced microbial activity. These findings underscore the important roles of carbon quality, microbial life-history strategies (K-strategies) and microbial activity in mediating the Q10 of Rs, especially in deep soils which are easily ignored. Based on these findings, it can be predicted that under global warming scenarios, temperate forests may experience accelerated SOC decomposition at horizontal spatial scales, especially in deeper soil layers. In subtropical forests, topsoil may exhibit more rapid carbon loss along vertical gradients.

Graphical abstract