Assessment of ActualEvapotranspiration Variability in Response to Vegetation Types along a Precipitation Gradient

Banihashemi, Elham; Tahmasebi, Pejman; Ghehsare, Elham; Abdollahi, Khodayar

doi:10.22059/ije.2026.397981.1877

Assessment of ActualEvapotranspiration Variability in Response to Vegetation Types along a Precipitation Gradient

Document Type : Research Article

Authors

¹ Faculty of Natural Resources, University of Shahrekord, Shahrekord, Iran

² Department of Rangeland Ecology, Range and Watershed Management, Faculty of Natural Resources and Earth Sciences, Shahrekord University, Shahrekord, Iran

³ Department of Rangeland Sciences, Range and Watershed Management, Faculty of Natural Resources and Earth Sciences, Shahrekord University, Shahrekord, Iran

⁴ Department Water Engineering , Range and Watershed Management, Faculty of Natural Resources and Earth Sciences, Shahrekord University, Shahrekord, Iran

10.22059/ije.2026.397981.1877

Abstract

objective: Evapotranspiration (ET) is a key component of the hydrological cycle, governed by both climatic and biotic factors. This study aimed to investigate the response of ET to different vegetation growth forms along a precipitation gradient across steppe and semi-steppe rangelands in Chaharmahal and Bakhtiari and Isfahan provinces, Iran.
Method: Data were extracted from five rangeland sites with varying precipitation regimes and analyzed using a Generalized Linear Model (GLM).
Results: Results indicated that the precipitation gradient had a dominant and statistically significant effect on ET (p < 0.001), whereas the independent effect of vegetation growth forms was mostly nonsignificant. However, the interaction between growth forms and precipitation was significant in certain plant groups, particularly perennial grasses and shrubs (p < 0.05). Pearson correlation analysis also revealed a strong and positive relationship between vegetation cover and ET—especially for perennial grasses (r = 0.788, p < 0.001) and total vegetation cover (r = 0.957, p < 0.001).
Conclusion: These findings suggest that wetter regions supported denser vegetation and maintained higher ET without vegetation decline, indicating strong water recycling and vegetation persistence. In contrast, drier regions exhibited reduced vegetation cover and ET due to water limitations. Overall, the rainfall gradient plays a critical role in shaping vegetation structure and ET regime in dryland ecosystems.

Keywords

Main Subjects

Ecohydrology

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