Different Responses of Evapotranspiration Rates of Urban Lawn and Tree to Meteorological Factors and Soil Water in Hot Summer in a Subtropical Megacity
Urban evapotranspiration (ET) is an effective way to mitigate ecological challenges resulting from rapid urbanization. However, the characteristics of urban vegetation ET, especially how they respond to meteorological factors and soil water, remains unclear, which is crucial for urban ET regulation....
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| Autores principales: | , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/db5152e57b434497b938c2e75d397bef |
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| Sumario: | Urban evapotranspiration (ET) is an effective way to mitigate ecological challenges resulting from rapid urbanization. However, the characteristics of urban vegetation ET, especially how they respond to meteorological factors and soil water, remains unclear, which is crucial for urban ET regulation. Therefore, this study measured the actual ET rate of an urban lawn (ET<sub>lawn</sub>) using the Bowen ratio system and an urban tree (T<sub>tree</sub>) by a sap flow system in the hot summer of a subtropical megacity, Shenzhen. The results showed that the daily ET<sub>lawn</sub> was more restricted by energy (R<sub>s</sub>) and diffusion conditions (vapor pressure deficit, VPD), while the daily T<sub>tree</sub> was more restricted by VPD and relative extractable water (REW) in the urban area. The daily T<sub>tree</sub> decreased when the REW was lower than 0.18, while the daily ET<sub>lawn</sub> started to decrease when it was lower than 0.14. When REW was lower than 0.11, the T<sub>tree</sub> stayed at a relatively low level. The impacts of VPD was more evident on the diurnal T<sub>tree</sub> than on the diurnal ET<sub>lawn</sub>. Wind speed had a scarce impact as it was relatively low in urban areas. This study clarifies the different responses of ET<sub>lawn</sub> and T<sub>tree</sub> to meteorological factors and soil water based on actual ET. The results are of great significance for the knowledge of urban forestry and urban hydrology. |
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