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| DOI：10.13522/j.cnki.ggps.2024363 |
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| Seasonal variation in root water uptake of Paulownia in Eastern Henan Plain based on stable isotopes |
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LI Jianfei, TIAN Pengying, WANG Na, TANG Wu, OU Huidi,
FAN Guoqiang, ZHAO Zhenli, ZHANG Zhihua
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1. Henan Agricultural University, Zhengzhou 450002, China;
2. Lankao County Forestry Service Center, Kaifeng 475300, China;
3. Paulownia Research Institute of Henan Agricultural University, Zhengzhou 450002, China
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| Abstract: |
| 【Objective】Paulownia is a dominant tree species in the North China Plain and plays an important ecological and economic role in this region. Due to the increasing water scarcity in this region, understanding its water-use strategies is crucial for improving water resource management and environmental protection. This paper investigates the response of Paulownia to seasonal water stress, aiming to identify water in different soil layers that the plant uses at different growth stages.【Method】The experiment was conducted in forests of four-year-old and seven-year-old Paulownia trees. Stable hydrogen and oxygen isotopes (δD and δ18O) in precipitation, xylem water and soil water at different growing stages of the trees were analyzed. Spatiotemporal variations in isotopic concentrations across the soil profile were analyzed, from which a multi-source linear mixing model were developed to calculate the contribution of water in different soil depths to the transpiration. 【Result】① Soil water content varied with season and soil depth; it was mainly influenced by precipitation. Soil water content was higher in summer and lower in spring and autumn. ② The concentration of δD and δ18O fluctuated greatly in the top 0-30 cm soil water and were relatively stable in the subsoil water. ③ Paulownia trees used water in different soil layers in different seasons. When the age of the trees was the same, they used similar soil water sources in the same season under different growth conditions. Specifically, in summer, Paulownia trees of different ages used more subsoil water, while in autumn, the water used by the trees mainly stemmed from the top 0-20 cm soil layer, which accounted for 56.7% of the transpiration. In spring, the contribution of soil water from the 10-30 cm layer to the transpiration increased.【Conclusion】Water in the top 0-20 cm layer is the main source for Paulownia trees. Poor tree growth is often due to low soil water content. Therefore, maintaining water content in the 0-20 cm layer at a certain level is essential to ensuring the healthy growth of Paulownia. |
| Key words: water use source; δD and δ18O; Paulownia plantation; MixSIAR; Eastern Henan Plain |
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