Under drought stress, desert riparian forest plants are highly self-regulating and have their own unique water use and regulation strategies, which can respond positively in several aspects such as physiology, ecology, and individual phenotypes when coping and adapting to the stresses brought by external environmental changes. In addition, as an important component of arid zone ecosystems, desert riparian forest plants maintain the cycling process of energy and material in desert areas. Therefore, it is of great ecological value to study the role played by desert riparian forest plants in desertification control and biodiversity conservation in arid zones. The purpose of this study is to provide basic data and scientific basis for the conservation, and restoration of desert riparian forests in the inland river basin of arid zone. In this paper, the physiological and ecological responses of desert riparian plants under drought stress were analyzed by reviewing the literature and focusing on the key scientific issues such as drought avoidance mechanisms, water use, and water redistribution, and the relationship between interspecific water competition and resource sharing of desert riparian plants. The results showed that: (1) In the inland river basin of arid zone, desert riparian plants show a mutual coordination of increasing soluble sugars, proline, malondialdehyde (MDA), and decreasing peroxidase (POD), to form a unique drought avoidance mechanism, and improve their drought tolerance by changing leaf stomatal conductance resulted from regulating abscisic acid (ABA) and cytokinin (CTK) content. (2) Desert riparian forest plants have their own unique water use and regulation strategies. When the degree of drought stress increased, Populus euphratica enhanced the water flow of dominant branches by actively sacrificing the inferior branches to ensure and improve the overall survival chances of the plant, while Tamarix ramosissima weaken hydraulic conductance, and increase subsurface material inputs by reducing plant height to cope with drought stress. (3) The root systems of desert riparian plants have hydraulic uplift and water redistribution functions, and, in the hydraulic uplift process of P. euphratica and T. ramosissima root systems, there is a possibility of assisting with other species in water utilization and the existence of a resource sharing mechanism.

Changes in the resistance, recovery, and resilience of three desert riparian ecosystems to extreme droughts and the influence of ecological characteristics on them from 2000 to 2020 were analyzed within the Tarim River Basin, Xinjiang, China. The results showed that: (1) The resistance of the Populus euphratica forest community was the highest among the three plant communities. The recovery and resilience of the shrub community were the highest; (2) the resilience increased the most for the shrub community and decreased slightly for the Populus euphratica forest and herb communities as hydrological droughts waned; (3) the relative height and density significantly increased for Populus euphratica, decreased for herbs, and did not change for shrubs from 2000 to 2020; (4) the diversity indexes did not significantly change for the Populus euphratica forest and herb communities, and they increased for the shrub community from 2000 to 2020; (5) the resistance and resilience of the Populus euphratica forest, shrub, and herb communities were significantly affected by ecological characteristics, especially the Margalef richness index; and (6) the shrub community is more likely to rapidly recover (that is an increase of cover, height, and density) from future droughts in the Tarim River Basin, particularly with the implementation of new and more effective ecological restoration projects.

Analysis of eco-environmental water requirements along a dry inland river under extreme drought conditions can provide a theoretical basis for the sustained utilization and management of water resources in arid regions. This paper uses the Yarkand River Basin in Xinjiang, China, as a case study to determine and assess a method to calculate targeted eco-environmental water requirements (TEEWR) for different ranges of ecological protection of inland riparian forests. The proposed method is intended to comprehensively analyze the water resources along arid inland rivers. Specifically, the ranges of ecological protection were gradually expanded at intervals of 1 km (or multiples of the smallest distance) away from the river course while the TEEWR was determined as a function of the ecological water demand of riparian forest vegetation (Y_ec) and its corresponding river loss (X_loss). The developed method was shown to be feasible for analyzing TEEWR in the Yarkand River Basin and thus provides a novel and effective approach for the rational utilization and management of water resources in inland river basins in arid regions. Article Highlights Zones of ecological protection were gradually expanded at intervals of 1 km (or multiples of the smallest distance) away from the river course on both sides of the dry inland river The targeted eco-environmental water requirement, defined as the ecological water demand of riparian forest vegetation (Y_ec) and its corresponding river loss (X_loss), was determined for a dry inland river basin The developed methods for calculating targeted eco-environmental water requirements are useful, but have limitations.

Analysis of basic eco-environmental water requirements (BEEWRs) along inland rivers characterized by extreme aridity can provide a theoretical basis for sustaining riverine ecosystems stressed by increasingly dry conditions and human activity. In the past, analyzing the ecological base flow as determined by the Tennant method was the predominant method used to calculate the BEEWR of a river. However, some parameter values within this method are determined subjectively, increasing uncertainty in the estimated values. In this paper, quantitative methods for these subjectively determined parameters are proposed and used to analyze the BEEWR of the Yarkand River, Xinjiang, China. The results demonstrate that: (1) the flood and non-flood seasons of a river can be delineated by analyzing the increase rate of monthly runoff as compared to the monthly runoff of the previous month; (2) the ecological base flow standard in the Tennant method can be more quantitatively determined by comparing the BEEWR for each ecological base flow standard to the annual average river loss, where the BEEWR must exceed the annual average river loss; and (3) BEEWRs of other up- and downstream river reaches can be obtained using the formula “BEEWR in the next downstream section equals the BEEWR in the last section minus the river loss between these two sections”.

The main objective of this work is to calculate the suitable scale of the Ejina Oasis in different scenarios (high-, normal-, and low-flow years), assess the stability of the Ejina Oasis, and, finally, accurately determine if an artificial oasis area and total oasis area need to be reduced or increased. Using the water balance method, we calculated the suitable scale of the artificial Ejina Oasis as 767.80, 624.00, and 451.33 km² in high-, normal-, and low-flow years, respectively. By utilizing the water-heat balance method combined with an assessment of the present stability of the Ejina Oasis, the results showed that in high-flow years, the suitable scale of the Ejina Oasis is 1174–1762 km², and the stability index of the current oasis is 0.55. In normal-flow years, the suitable scale of the Ejina Oasis is found to be 915–1373 km², and the stability index of the current oasis is 0.43. In low-flow years, the suitable scale of the Ejina Oasis is 590–885 km², and the stability index of the current oasis decreases to 0.27. In order to further improve the stability of oases, it remains necessary to control the scale of oases to cope with water resource shortages that result from water resource instability under climate change. The present study’s findings will enable optimal water-use planning decisions that take social, economic, and ecological issues into account, and provide the foundation for optimal decision-making for regional administrative departments to effectively coordinate regional economic development, farmland protection, environmental protection, and water resource protection.