Characteristics of ecosystem water use efficiency in a desert riparian forest
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The Ejin oasis, located on the river sides of a hyper-arid region, represents some of the richest desert ecosystems, populated with riparian forest. Water availability is the main limited factors for the distribution and growth of the forest. Currently, the water–carbon process and mechanisms in the desert riparian forest remain uncertain. The study investigated the seasonal and inter-annual variations in the gross primary productivity (GPP), evapotranspiration (ET) and ecosystem water use efficiency (WUE), and their relationships with the event (e.g., irrigation) and climatic factors. The results showed that the desert riparian forest produced new plant biomass with 0.79 g C kg−1 of water loss during the growing season. In the study period, monthly GPP and ET was tightly coupled, and the mean cumulative GPP and ET from May–October were 676 g C m−2 and 864 mm, respectively. Daily GPP and ET had similar relationships with global radiation (Rg), air temperature (Ta) and vapor pressure deficit at monthly scale. Consequently, the seasonal variations in WUE were not obvious in the growing season, except in September. In September, the value of WUE decreased significantly with an increase in Ta (for Ta > 15 °C) after irrigation, which was attributable to the increased ET and a relatively steady GPP. It is possible that the time of irrigation is able to affect the seasonal course of WUE. The study has implications that enable more rational water management to maintain the the health and activities of the riparian forest in such a hyper-arid region.
KeywordsEcosystem water use efficiency The desert riparian forest Irrigation effects
This work was supported by National Key R&D Program of China (2017YFC0404305). This work also was funded by the National Natural Science Foundation of China (Nos. 31370467 and 41401033). The authors thank anonymous referees for their reading of this manuscript and helpful reviews and comments.
Xiaohong Ma analyzed data and wrote the paper; Qi Feng conceived the study; Yonghong Su and Ravinesh Deo revised the paper; Tengfei Yu collected data and also revised the paper.
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Conflict of interest
The authors declare that they have no conflict of interest.
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