Background and aims Understanding the plant water-use strategies under varying drought intensities is essential for regional ecological restoration. Methods We collected precipitation, soil water, and xylem or stem water from representative restoration trees, fruit trees, herbaceous species, and crops across different geomorphic settings in the eastern Chinese Loess Plateau during 2023–2024. Using δ2H and δ1⁸O in combination with the MixSIAR model, we investigated the water-use strategies of different plant species across distinct geomorphic units, and further applied partial least squares path modeling to elucidate the mechanisms underlying plant water-use responses to different drought intensities. Results Soil water δ1⁸O exhibited a clear pattern of enrichment in the surface layer and depletion in deeper layers, while lant water δ1⁸O varied substantially among geomorphic zones, with the greatest stability observed in the river-valley plain region. δ1⁸O variability differed markedly among plant species, while tree species showing greater fluctuations than herbaceous plants. Plants mainly relied on precipitation and shallow soil water during the early and late rainy season, and shifted to middle- and deep-layer water sources during the dry season. Seasonal variation in plant water use was smaller in 2023 than in 2024, and herbaceous species and crops mainly depended on precipitation and shallow soil water. Ecological restoration trees exhibited seasonal shift in water uptake, whereas fruit trees maintained a relatively stable dependence on mid-layer soil water. Natural vegetation showed greater flexibility in shifting water sources with drought intensified from moderate to extreme levels, whereas restored vegetation displayed limited plasticity and weaker adaptive capacity. Path analysis indicated that the dominant regulatory pathways of plant water-source partitioning varied among drought classes, shifting from combined atmospheric and vegetation-structural effects under moderate to severe drought to stronger precipitation-related regulation under extreme drought. Conclusions This study suggest that restoration practitioners should match species selection and planting density with local drought intensity, geomorphic position, and water-source availability, prioritizing native or locally adapted species with flexible water-source use in drought-prone or water-limited sites.

Response and adaptation of plant water use strategies to drought intensity gradients in ecological restoration areas of the Eastern Loess Plateau

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发表日期：

2026年7月10日

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Congjian Sun,
Jiahao Du,
Wei Chen

摘要

Background and aims

Understanding the plant water-use strategies under varying drought intensities is essential for regional ecological restoration.

Methods

We collected precipitation, soil water, and xylem or stem water from representative restoration trees, fruit trees, herbaceous species, and crops across different geomorphic settings in the eastern Chinese Loess Plateau during 2023–2024. Using δ²H and δ¹⁸O in combination with the MixSIAR model, we investigated the water-use strategies of different plant species across distinct geomorphic units, and further applied partial least squares path modeling to elucidate the mechanisms underlying plant water-use responses to different drought intensities.

Results

Soil water δ¹⁸O exhibited a clear pattern of enrichment in the surface layer and depletion in deeper layers, while lant water δ¹⁸O varied substantially among geomorphic zones, with the greatest stability observed in the river-valley plain region. δ¹⁸O variability differed markedly among plant species, while tree species showing greater fluctuations than herbaceous plants. Plants mainly relied on precipitation and shallow soil water during the early and late rainy season, and shifted to middle- and deep-layer water sources during the dry season. Seasonal variation in plant water use was smaller in 2023 than in 2024, and herbaceous species and crops mainly depended on precipitation and shallow soil water. Ecological restoration trees exhibited seasonal shift in water uptake, whereas fruit trees maintained a relatively stable dependence on mid-layer soil water. Natural vegetation showed greater flexibility in shifting water sources with drought intensified from moderate to extreme levels, whereas restored vegetation displayed limited plasticity and weaker adaptive capacity. Path analysis indicated that the dominant regulatory pathways of plant water-source partitioning varied among drought classes, shifting from combined atmospheric and vegetation-structural effects under moderate to severe drought to stronger precipitation-related regulation under extreme drought.

Conclusions

This study suggest that restoration practitioners should match species selection and planting density with local drought intensity, geomorphic position, and water-source availability, prioritizing native or locally adapted species with flexible water-source use in drought-prone or water-limited sites.