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Aims <p>Shrub encroachment has been widespread globally over the past century or two. However, changes in soil organic carbon (SOC), total nitrogen (STN), total phosphorus (STP), and their driving mechanisms during shrub encroachment remain unclear.</p> Methods <p>We explored the changes in SOC, STN, and STP, the driving factors, and their water thresholds during 40a anthropogenic shrub encroachment.</p> Results <p>The results showed that shrub encroachment increased shrub and litter biomass and plant total nitrogen and phosphorus contents, while decreasing herbaceous species richness (<i>P</i> &lt; 0.05). Furthermore, shrub encroachment reduced the contents and stocks of SOC, STN, and STP (<i>P</i> &lt; 0.05). Our results also indicated that shrub above-ground biomass exerted indirect negative effects on SOC, STN, and STP contents. Simultaneously, soil mineral-associated organic carbon and mineral-associated total nitrogen played direct positive roles in driving SOC and STN contents, respectively, while plant total phosphorus had a direct negative effect on STP contents. In addition, our results indicated that soil water played a central role in driving SOC, STN, and STP contents. As soil water content decreased, SOC and STN contents initially increased slightly, but declined sharply when soil water dropped below thresholds of 8.85% and 8.90%, respectively. In contrast, STP content exhibited a continuously decreasing trend, with the rate of decline slowing at the soil water threshold of 6.79%.</p> Conclusion <p>Our study showed that shrub encroachment resulted in a loss of SOC, STN, and STP, which was significantly influenced by vegetation type, soil mineral-associated organic matter fractions, and water thresholds.</p>

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Influencing factors and soil water thresholds of soil carbon, nitrogen, and phosphorus loss during anthropogenic shrub encroachment in desert steppes

  • 期刊论文

  • 发表日期：

    2026年6月25日

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  • Zhenjie Zhang,
  • Hongmei Wang,
  • Yanan Zhao,
  • Zhili Li,
  • Chen Chen,
  • Aotian Li,
  • Mengdi Liu,
  • B. Larry Li,
  • Jianping Li

摘要

Aims

Shrub encroachment has been widespread globally over the past century or two. However, changes in soil organic carbon (SOC), total nitrogen (STN), total phosphorus (STP), and their driving mechanisms during shrub encroachment remain unclear.

Methods

We explored the changes in SOC, STN, and STP, the driving factors, and their water thresholds during 40a anthropogenic shrub encroachment.

Results

The results showed that shrub encroachment increased shrub and litter biomass and plant total nitrogen and phosphorus contents, while decreasing herbaceous species richness (P < 0.05). Furthermore, shrub encroachment reduced the contents and stocks of SOC, STN, and STP (P < 0.05). Our results also indicated that shrub above-ground biomass exerted indirect negative effects on SOC, STN, and STP contents. Simultaneously, soil mineral-associated organic carbon and mineral-associated total nitrogen played direct positive roles in driving SOC and STN contents, respectively, while plant total phosphorus had a direct negative effect on STP contents. In addition, our results indicated that soil water played a central role in driving SOC, STN, and STP contents. As soil water content decreased, SOC and STN contents initially increased slightly, but declined sharply when soil water dropped below thresholds of 8.85% and 8.90%, respectively. In contrast, STP content exhibited a continuously decreasing trend, with the rate of decline slowing at the soil water threshold of 6.79%.

Conclusion

Our study showed that shrub encroachment resulted in a loss of SOC, STN, and STP, which was significantly influenced by vegetation type, soil mineral-associated organic matter fractions, and water thresholds.