Drought and salinity are considered to be the major limiting factors for plant growth in desert areas. Halophytes can maintain their growth in extreme salt environments. However, few studies have linked the photosynthetic characteristics of halophytes with their anatomical structures and leaf water potential to jointly explain the effects of drought and salt on leaf internal water use efficiency (WUEi). For this reason, two different halophytes, Nitraria sibirica and Alhagi sparsifolia, were selected to analyze the leaf physiological traits in response to different water and salt gradients. The analysis further revealed the influence of soil water and salt content and anatomical characteristics on plant photosynthesis. The results showed that the leaf water potential, morphology, anatomical parameters, and photosynthetic parameters of the two plants in different habitats showed significant species-specific physiological responses. The value of WUEi of N. sibirica was negatively correlated with net photosynthetic rate (Pn), stomatal conductance (Gs), tightness of palisade tissue (CTR), and soil factors, while the WUEi of A. sparsifolia was positively correlated with Pn, Gs, and CTR. The indirect effects of soil salinity and soil moisture on WUEi were also found to be species-specific. This study will help to improve the understanding of the ecological adaptability of plants to water and salt stress and provide a theoretical basis for clarifying the drought tolerance and salt tolerance adaptation strategies of halophytes in arid areas.

Foliar water uptake (FWU) is considered to be a common phenomenon in most terrestrial plants. As a supplementary water source, it plays an important role in the growth and survival of plants in arid areas. However, there is no research to explain the water absorption of plant leaves from the perspective of gender specificity. To this end, we carried out a leaf water absorption capacity experiment and in situ wetting field experiment, respectively, in the early (Initial), middle (Mid) and end (End) of the growth season of male and female Populus euphratica. The results of the leaf water absorption capacity experiment showed that the FWU capacity of male and female P. euphratica showed an increasing trend with the growth period and reached the maximum at the End period. The FWU capacity of female P. euphratica was significantly greater than that of male P. euphratica after the Initial stage. The water absorption speed (k) of male and female leaves also increased with the growth period, but the increase was not significant. The increase in leaf water content per mg of water absorbed per unit of leaf area (LWC_A) of male P. euphratica was always greater than that of female P. euphratica. Specific leaf area (SLA), leaf water saturated deficit (WSD) and water absorption parameters (FWU capacity, k) were significantly correlated. The results of the in situ wetting field experiment show that humidification significantly increased the predawn water potential (Mid period) of female and male P. euphratica leaves and the net photosynthetic rate (Mid period) of male P. euphratica leaves, but had no significant effect on chlorophyll fluorescence parameters and anatomical structure. The MFA results show that the water status of male and female P. euphratica leaves was significantly correlated with photosynthetic parameters, fluorescence parameters and anatomical parameters. Our results show that the foliar water uptake capacity of female P. euphratica leaves was stronger than that of male P. euphratica and shows significant dynamic changes during the growing season. This was because female P. euphratica has a developed water storage structure. Foliar water uptake can effectively improve the water status and photosynthetic capacity of male and female P. euphratica, and this improvement was more significant during the most intense period of soil water stress. These findings will deepen our understanding of the ecological adaptation of dioecious plants to foliar water uptake.

The absorption of atmospheric water by plants through their leaves, known as leaf water uptake, plays a crucial role in sustaining plant growth and survival in arid regions. Condensate is one of the important sources of water for plants in arid zones and plays an important role in alleviating the physiological state of plant water. In order to clarify the ecological role of the leaf absorption of condensation water, we took the dominant species of the desert Dugay forest plant, Populus euphratica, as the research object, and based on in situ leaf humidification field experiments, we comprehensively analyzed the effect of condensation water on the physiological state of P. euphratica and the ecological benefit of leaf water absorption on the arid zone by determining the parameters of the physiological indexes of the leaf, the leaf wettability, and the water-absorbing capacity of the leaf. The results showed that P. euphratica leaves have a water-absorbing ability on both sides, and under the condensation water treatment, the water potential of dawn leaves in the TR group (−1.75 ± 0.12 MPa) was significantly higher than that in the CK group (−1.41 ± 0.13 Mpa); the net photosynthetic rate of leaves in the TR group (13.08 ± 0.68 μmol·m⁻²·s⁻¹) was significantly higher than that in the CK group (10.42 ± 0.57 μmol·m⁻²·s⁻¹); the proline content of the TR group (22.82 ± 0.8 μg·g⁻¹) was significantly lower than that of the CK group (68.67 ± 6.14 μg·g⁻¹); and the leaf photosynthetic capacity, leaf osmotic adjustment, and stress tolerance affected by condensation water were significantly different (p < 0.05). A leaf’s water-absorbing ability is mainly affected by leaf wettability, the proline content, and other influencing factors. The mean FWU rate was positively correlated with the mean transpiration rate. Within the Ebinur Lake watershed, the water absorption rate of P. euphratica leaves accounts for 10.92% of the maximum transpiration rate (T_r); in 2022, the total summer leaf surface water uptake by P. euphratica was about 220.5 mol, a value that represents about 0.25% of the average annual evapotranspiration from Ebinur Lake. This study helps to improve the understanding of the impact of condensation water on the physiological ecology of the desert plant P. euphratica and provides a scientific basis for the ecological benefits of leaf water absorption in arid regions.

Understanding the spatial variation law of soil respiration (Rs) and its influencing factors is very important when simulating and predicting the terrestrial carbon cycle process. However, there are still limitations in understanding how different sampling scales affect the spatial heterogeneity of Rs and whether the spatial scale effect will change with habitat types. Our objectives were to explore the effects of different sampling scales on the spatial variability of Rs and the relative importance of soil abiotic characteristics and plant traits in influencing the spatial variability of Rs. The Rs, soil properties, and plant traits were measured through field investigation and indoor analysis in the Tugai forest desert plant community in the Ebinur Lake Basin in northwest China. The Rs showed significant water gradient changes, with a coefficient of variation of 35.4%–58%. Plot types had significant effects on Rs, while the change of sampling scale did not lead to significant differences in Rs. At the plot scale, Rs spatial variation at the 5 m × 5 m sampling scale mainly depended on plant traits (leaf length, leaf thickness, leaf dry matter content, and leaf phosphorus content, p < 0.05), while Rs spatial variation at the 10 m × 10 m scale mainly depended on soil properties (soil total phosphorus, ammonium nitrogen, soil water content, and pH, p < 0.05). At the local scale, soil nutrients (soil available phosphorus and ammonium nitrogen) and plant traits (maximum plant height, leaf length, and phosphorus content) at the 5 m × 5 m scale jointly explained 49% of the spatial change of Rs. In contrast, soil microclimate (soil water content), soil nutrients (soil pH, available phosphorus, and nitrate nitrogen), and plant traits (leaf thickness) jointly explained 51% of the spatial variation of Rs at the 10 m × 10 m scale. These results demonstrate the potential to predict the spatial variability of Rs based on the combination of easily measured aboveground functional traits and soil properties, which provides new ideas and perspectives for further understanding the mechanism of Rs change in Tugai forests.