Xue-Ni Zhang

Understanding the relationships among plant functional traits and how these are shaped by the soil environment is essential for the study of plant adaptation. Conducted in the desert ecosystem surrounding Ebinur Lake, China, this study assessed key functional traits for eight common desert plant species, including the foliar carbon (C), nitrogen (N), and phosphorus (P) content, and their stoichiometric ratios (C:N, C:P, N:P), as well as the chlorophyll content (Chl), leaf area (LA), and leaf thickness (LT). Separate plant trait networks (PTNs) were constructed for herbs, shrubs, and trees growing in two distinct soil environments: those with high (HS) versus low (LS) soil moisture and salinity. The study had three key findings. (1) Both soil properties and plant functional traits differed between HS and LS environments (p < 0.05). (2) Distinct PTNs were observed among plant life forms, with different central traits. Herbs (central traits: leaf thickness and the N:P ratio) had high-density PTNs demonstrating strong adaptability, while shrubs (central traits: C and P) and PTNs had high connectivity that was stable across soil environments; tree PTNs (central traits: N and the C:P ratio) were highly modular and showed strong resistance to disturbance. (3) Soil factors also regulated PTN topology, with the total nitrogen (TN) and total phosphorus (TP) being key regulators in HS, while the soil salt content and water content were the most important factors in LS. In conclusion, the PTNs of desert plants reflected their unique adaptations to arid environments, and the application of these findings should support efforts to conserve and manage desert vegetation.

Understanding the relationships among plant functional traits and their responses to soil environments is crucial for clarifying plant adaptation strategies. Conducted in the Ebinur Lake region, this study measured key functional traits of desert plants, including carbon (C), nitrogen (N), phosphorus (P) contents, leaf thickness (LT), leaf area (LA), chlorophyll content (Chl), and their ecological stoichiometric ratios (C:N, C:P, N:P). Plant Trait Networks (PTNs) were constructed for herbs, shrubs, and trees under high (HS) and low (LS) soil water-salt environments to analyze the structural differences and regulatory mechanisms of PTNs. The results showed that: (1) There were significant differences in soil properties and plant functional traits between HS and LS environments (p < 0.05), with higher soil water and salt contents in HS. (2) Significant differences in PTNs were observed among different life forms with distinct central traits: Herbs (central traits: leaf thickness, N:P ratio) had high-density PTNs and strong adaptability; Shrubs (central traits: C, P) had high connectivity and stable adaptability; Trees (central traits: N, C:P ratio) had high-modularity PTNs and strong anti-interference ability. (3) Soil factors regulated PTN structure differently: total nitrogen (TN) and total phosphorus (TP) were the key regulatory factors in HS, while soil salt content and water content were the main influencing factors in LS. In conclusion, the PTN structure of desert plants is an important reflection of their adaptation to arid environments, providing a theoretical basis for the protection and management of arid zone vegetation.

Plant interactions and their responses to stress environments are important ecological processes for ecosystem stability and biodiversity formation, but how plant intraspecific relationships respond to environmental stresses remains to be studied in depth. In this study, annual Populus euphratica seedlings were planted in singles or doubles, and two stress treatments were set up: two drought levels (0.7 and 0.4 L) and two salinity levels (200 and 400 mmol L⁻¹). P. euphratica seedlings’ total and part biomass, root/shoot ratio, net photosynthetic rate, stomatal conductance, nonstructural carbohydrate concentration, and proline content were measured. Relative interaction indices were calculated to clarify their intraspecific relationships. The results of the study showed that compared to the single-planted P. euphratica, the double-planted P. euphratica was more significantly inhibited by drought and salt stress, the total biomass decreased, photosynthesis declined, proline content increased, and non-structural carbohydrates changed, which reflected a competitive intraspecific relationship. Secondly, as drought and salt stress intensified, the relative interaction index indicated that the intraspecific relationship of P. euphratica seedlings gradually shifted from neutrality to competition, which indicated that the intraspecific competitive relationship of P. euphratica seedlings was exacerbated by environmental stresses. These findings highlight the need to account for stress-mediated competition in P. euphratica seedlings during ecological restoration in arid environments.

Introduction: Functional traits of desert plants exhibit remarkable responsiveness, adaptability and plasticity to environmental heterogeneity.Methods: In this study, we measured six crucial plant functional traits (leaf carbon, leaf nitrogen, leaf phosphorus, leaf thickness, chlorophyll concentration, and plant height) and employed exemplar analysis to elucidate the effects of soil environmental heterogeneity on intraspecific traits variation in the high-moisture-salinity and low-moisture-salinity habitats of the Ebinur LakeWetland National Nature Reserve.Results: The results showed that (1) The soil moisture and electrical conductivity heterogeneity showed significant differences between the two moisture-salinity habitats. Moreover, soil nutrient in high moisture-salinity habitat exhibited higher heterogeneity than in low moisture-salinity habitat. The order of intraspecific trait variation among different life forms was herbs > shrubs > trees in both the soil moisture-salinity habitats. (2) At the community level, intraspecific variation of leaf carbon, nitrogen, plant height and chlorophyll content in high moisture-salinity habitat was higher than that in low moisture-salinity habitat, while the opposite was true for leaf thickness and leaf phosphorus content. (3) Our findings revealed a positive impact of soil heterogeneity on intraspecific traits variation. In high moisture-salinity habitat, the heterogeneity of soil organic carbon had the highest explanatory power for intraspecific traits variation, reaching up to 20.22%, followed by soil total nitrogen (9.55%) and soil total phosphorus (3.49%). By comparison, in low-moisture-salinity habitat, the heterogeneity of soil moisture alone contributes the highest explanatory power for intraspecific traits variation in community-level, reaching up to 13.89%, followed by the heterogeneity of soil total nitrogen (3.76%).Discussion: This study emphasizes the differences in soil heterogeneity and intraspecific trait variation among plant life forms under various soil moisture-salinity habitats and confirms the significant promoting effect of soil heterogeneity on intraspecific trait variation of desert plant. Our findings provide valuable theoretical basis and reference for predicting plant adaptation strategies under environmental change scenarios.

Understanding the relationship between soil environmental conditions and the interspecific integration of plant traits might shed light on how plants adapt to their environment. In order to clarify the adaptation strategies of desert plants in the various habitats, this study calculated interspecific trait integration (ITI) and plant trait networks (PTN) by selecting plants from high water-salinity habitat (HSM) with salt stress and low water-salinity habitat (LSM) with drought stress in the Ebinur Lake region. Eight different phytochemical traits were taken into consideration, including carbon (C), nitrogen (N), phosphorus (P), sulfur (S), potassium (K), calcium (Ca), sodium (Na), and magnesium (Mg). Six soil factors were chosen, including soil pH, water content (SVWC), electrical conductivity (EC), soil nitrogen (N), phosphorus (P), and potassium (K). The results obtained are shown below: (1) the relationship between plant leaf chemical traits was closer in HSM than in LSM, and the correlation between C and other leaf chemical traits was significant in HSM and insignificant in LSM; (2) the correlations between soil factors and ITI were not statistically significant; however, in both soil water-salinity habitats, the strength of fit between SVWC and ITI was the greatest, while the strength of fit between EC and ITI was the smallest; and (3) according to the PTN, C and Ca are the two most central traits for the growth of desert leaf chemical plants in Ebinur Lake, which is consistent with the results of the PCA. Coordination of plant leaf traits along water-salinity gradients involves many different combinations of traits, and the use of ITI and PTN can quantify the complex relationships between multiple traits to a greater extent, highlighting the multivariate mechanisms of plant response and adaptation to soil habitats. This information will help expand and optimize our ability to observe and predict desert plant responses to habitat change, providing powerful insights for assessing desert plant survival strategies.

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.

Background: Trait-based approaches have been used to demonstrate the responses of plant functional traits to environmental change may manifest both among- and/or within-species. However, how community-level foliar stoichiometric characteristic variations respond to aridity and salinity is still not well-known.Methods: We calculated community weighted means (CWMs) and non-weighted means (CMs) of foliar C, N, and P concentrations (and their ratios) in a dryland plant community respond to high (HSW) and low soil moisture and salinity (LSW). Based on a sum of squares decomposition method, we determined the relative contributions of intraspecific variation and species turnover in both HSW and LSW habitats.Results: The CWMs of foliar C, C:N and C:P, and CM of N in the HSW habitat were significantly greater than those in the LSW habitat. The trait variations in two habitats were mainly driven by intraspecific variation, and its contribution to trait variation mostly declined with the decrease of soil moisture and salinity. The CWMs of foliar C-related stoichiometric characteristics were mainly dominated by species turnover in both habitats. Moreover, the contribution of species turnover to C and C:P variations showed an increasing trend in the LSW habitat. For CWMs, negative covariations between intraspecific variation and turnover occurred in HSW and positive covariations (except N:P) occurred in LSW; however, CMs were generally positively correlated in both habitats.Conclusions: The intraspecific variation declined as drought stress intensified, which indicates that the adaptability of desert plants declined when the stress changed from salinity to aridity. The total variation of C-related traits in both habitats were mainly dominated by species turnover. These findings highlight the importance of intraspecific variation in driving desert plant response of community functional composition to salt stress, and the joint role of intraspecific variation and species turnover in resisting drought stress.

The Pleistocene climatic oscillations had profound effects on the demographic history and genetic diversification of plants in arid north-west China where some glacial refugia have been recognized. The genus Ixiolirion comprises three species, of which two, I. tataricum and I. songaricum (endemic), occur in China. In some locations they are sympatric. We investigated their population structure and population history in response to past climatic change using a sample of 619 individuals in 34 populations with nITS and ptDNA sequences. A significant genetic divergence between the two species was supported by a high level of pairwise genetic differentiation, very low gene flow, and phylogenetic analysis showing that I. songaricum haplotypes were monophyletic, whereas those of I. tataricum were polyphyletic. We found significant differentiation and phylogeographic structure in both species. The split of the two species was dated to the late Miocene (∼7 Ma), but deep divergence occurred in the mid-late Quaternary. A similar haplotype distribution pattern was found in both species: one to two dominant haplotypes across most populations, with unique haplotypes in a few populations or a geographic group. The genetic diversity, haplotype number, and haplotype diversity decreased from the Yili Valley to the central Tianshan and Barluk Mountains. Additionally, ptDNA analysis showed that I. tataricum diversified in the eastern Tianshan and Barluk Mountains, which might be due to physical barriers to long distance seed dispersal such as desert. In conclusion, our results indicated that the Yili Valley was likely a glacial refuge for Ixiolirion in China, with postglacial dispersal from the Yili Valley eastward to the eastern Tianshan Mountains, and northward to the Barluk Mountains. The climatic changes in the Miocene and Pleistocene and geographic barriers are important factors driving species divergence and differentiation of Ixiolirion and other taxa.

The hydraulic redistribution (HR) of deep-rooted plants significantly improves the survival of shallow-rooted shrubs and herbs in arid deserts, which subsequently maintain species diversity. This study was conducted in the Ebinur desert located in the western margin of the Gurbantonggut Desert. Isotope tracing, community investigation and comparison analysis were employed to validate the HR of Populus euphratica and to explore its effects on species richness and abundance. The results showed that, P. euphratica has HR. Shrubs and herbs that grew under the P. euphratica canopy (under community: UC) showed better growth than the ones growing outside (Outside community: OC), exhibiting significantly higher species richness and abundance in UC than OC (pP. euphratica crown area in UC (R² = 0.51 and 0.84, pP. euphratica HR significantly ameliorates the water conditions of the shallow soil, which then influences the diversity assembly in arid desert communities.