Scholarlink

Background and aims <p>Grassland restoration through cropland abandonment enhances soil carbon sequestration, yet microbial necromass carbon (MNC) dynamics remain poorly understood across contrasting ecosystems. This study quantifies MNC accumulation and its contribution to SOC during post-abandonment succession, and elucidates whether underlying mechanisms differ between two steppe types with contrasting moisture availability.</p> Methods <p>Using a space-for-time substitution approach, we investigated MNC dynamics across 5-, 15-, and 20-year post-abandonment chronosequences in desert and typical steppe of Inner Mongolia, China. Amino sugar biomarkers were analyzed to quantify fungal and bacterial necromass carbon, and structural equation modeling was employed to disentangle pathways regulating MNC accumulation.</p> Results <p>After 20&#xa0;years of restoration, MNC increased by 115% in desert steppe and 141% in typical steppe compared to croplands, yet remained 23% and 56% below natural grassland levels, respectively. MNC exhibited pronounced delayed recovery, lagging behind vegetation and soil improvements by over a decade. Although both steppes showed convergent successional trajectories, regulatory mechanisms diverged fundamentally: in typical steppe, MNC was directly promoted by SOC and MBC through plant- and pH-driven pathways, whereas in desert steppe, MNC accumulation was constrained by abiotic factors (soil water content and bulk density) and mediated solely by MBC, with no direct SOC contribution.</p> Conclusion <p>Passive restoration rebuilds microbial-derived carbon pools, but did not reach natural grassland levels within 20&#xa0;years. Ecosystem-specific MNC drivers underscore the need for tailored restoration strategies: mesic grasslands benefit from vegetation-mediated carbon inputs, whereas arid systems require alleviation of physical constraints to unlock microbial carbon sequestration.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Contrasting drivers of microbial necromass carbon accumulation during post-abandonment succession in two semi-arid steppes

  • 期刊论文

  • 发表日期：

    2026年6月22日

查看全文
  • Bin Zhang,
  • Yangzhen Deng,
  • Shaoyu Li,
  • Feng Zhang,
  • Jiahua Zheng,
  • Lishan Yang,
  • Xiyuan Wang,
  • Zhiguo Li,
  • Mengli Zhao

摘要

Background and aims

Grassland restoration through cropland abandonment enhances soil carbon sequestration, yet microbial necromass carbon (MNC) dynamics remain poorly understood across contrasting ecosystems. This study quantifies MNC accumulation and its contribution to SOC during post-abandonment succession, and elucidates whether underlying mechanisms differ between two steppe types with contrasting moisture availability.

Methods

Using a space-for-time substitution approach, we investigated MNC dynamics across 5-, 15-, and 20-year post-abandonment chronosequences in desert and typical steppe of Inner Mongolia, China. Amino sugar biomarkers were analyzed to quantify fungal and bacterial necromass carbon, and structural equation modeling was employed to disentangle pathways regulating MNC accumulation.

Results

After 20 years of restoration, MNC increased by 115% in desert steppe and 141% in typical steppe compared to croplands, yet remained 23% and 56% below natural grassland levels, respectively. MNC exhibited pronounced delayed recovery, lagging behind vegetation and soil improvements by over a decade. Although both steppes showed convergent successional trajectories, regulatory mechanisms diverged fundamentally: in typical steppe, MNC was directly promoted by SOC and MBC through plant- and pH-driven pathways, whereas in desert steppe, MNC accumulation was constrained by abiotic factors (soil water content and bulk density) and mediated solely by MBC, with no direct SOC contribution.

Conclusion

Passive restoration rebuilds microbial-derived carbon pools, but did not reach natural grassland levels within 20 years. Ecosystem-specific MNC drivers underscore the need for tailored restoration strategies: mesic grasslands benefit from vegetation-mediated carbon inputs, whereas arid systems require alleviation of physical constraints to unlock microbial carbon sequestration.