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Background and Aims <p>Plant biomass allocation, often expressed as the root: shoot ratio (RSR), is essential for understanding plant adaptations to environmental changes and global carbon distribution. Changes in groundwater depth driven by climate change can significantly affect biomass allocation in brackish wetland ecosystems. However, the response of the RSR in plant communities to groundwater depth changes remains unclear.</p> Methods <p>To address this, we conducted in situ experiments across three groundwater depth gradients (-100&#xa0;cm, -60&#xa0;cm, and -20&#xa0;cm) in a brackish wetland in the Yellow River Delta.</p> Results <p>Our results showed that biomass allocation changes in plant communities are primarily influenced by dominant species in the brackish wetland. As groundwater depth decreased from -100&#xa0;cm to -20&#xa0;cm, soil electrical conductivity increased, plant diversity declined, and the dominant species shifted from <i>Phragmites australis</i> to <i>Suaeda salsa</i>. Reduced groundwater depth also promoted greater aboveground biomass allocation within plant communities. Compared to the deeper groundwater depths of -100&#xa0;cm and -60&#xa0;cm, the shallower groundwater depth of -20&#xa0;cm was associated with higher soil salinity and nutrient levels, including microbial biomass carbon, total nitrogen, and total phosphorus, which contributed to the increased biomass allocation to aboveground structures in both dominant species and plant communities. Additionally, the increased aboveground biomass allocation with decreasing groundwater depth is related to the reduction in plant diversity and the shift in plant species composition.</p> Conclusion <p>Our findings confirm that reduced groundwater depth enhances aboveground biomass allocation by increasing soil salinity and nutrients while simultaneously reducing plant diversity in brackish wetland ecosystems, which is consistent with optimal allocation theory. These insights provide a scientific basis for predicting vegetation productivity and developing management strategies for brackish wetlands under future groundwater change scenarios.</p>

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Reduced groundwater depth decreases plant diversity but increases plant aboveground biomass allocation in a brackish wetland

  • 期刊论文

  • 发表日期：

    2025年4月28日

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  • Yangjian He,
  • Mingliang Zhao,
  • Lianjing Wang,
  • Xiaojing Chu,
  • Xiaojie Wang,
  • Peiguang Li,
  • Xiaoshuai Zhang,
  • Weimin Song,
  • Qingju Hao,
  • Yiqi Zhao,
  • Changsheng Jiang,
  • Guangxuan Han

摘要

Background and Aims

Plant biomass allocation, often expressed as the root: shoot ratio (RSR), is essential for understanding plant adaptations to environmental changes and global carbon distribution. Changes in groundwater depth driven by climate change can significantly affect biomass allocation in brackish wetland ecosystems. However, the response of the RSR in plant communities to groundwater depth changes remains unclear.

Methods

To address this, we conducted in situ experiments across three groundwater depth gradients (-100 cm, -60 cm, and -20 cm) in a brackish wetland in the Yellow River Delta.

Results

Our results showed that biomass allocation changes in plant communities are primarily influenced by dominant species in the brackish wetland. As groundwater depth decreased from -100 cm to -20 cm, soil electrical conductivity increased, plant diversity declined, and the dominant species shifted from Phragmites australis to Suaeda salsa. Reduced groundwater depth also promoted greater aboveground biomass allocation within plant communities. Compared to the deeper groundwater depths of -100 cm and -60 cm, the shallower groundwater depth of -20 cm was associated with higher soil salinity and nutrient levels, including microbial biomass carbon, total nitrogen, and total phosphorus, which contributed to the increased biomass allocation to aboveground structures in both dominant species and plant communities. Additionally, the increased aboveground biomass allocation with decreasing groundwater depth is related to the reduction in plant diversity and the shift in plant species composition.

Conclusion

Our findings confirm that reduced groundwater depth enhances aboveground biomass allocation by increasing soil salinity and nutrients while simultaneously reducing plant diversity in brackish wetland ecosystems, which is consistent with optimal allocation theory. These insights provide a scientific basis for predicting vegetation productivity and developing management strategies for brackish wetlands under future groundwater change scenarios.