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[Objective] The characteristics of sand and dust transport amount and particle size on the windward and leeward sides of a natural Populus euphratica riparian forest at the Arghan section of the lower reaches of the Tarim River under the prevailing wind direction were studied in order to provide a theoretical basis for its windbreak and sand fixation capacity. [Methods] Sediments were collected from two windward sites (Y1 and Y2) and two leeward sites (B1 and B2) of the forest at five heights of 10, 30, 50, 100, and 150 cm near the surface using a BSNE sand collector. The particle size characteristics of the sand samples were then measured using a Microtrac S3500 laser diffraction particle size analyzer. [Results] ① The horizontal flux of sand and dust in the four sample plots followed either a power function or exponential function distribution, and total sediment transport followed the order of Y1 > Y2 > B1 > B2. The sediment transport for each sample plot decreased with increasing height from the soil surface. ② The reduction of sediment on the leeward side compared with the windward side ranged from 35% to 80% less than on the windward side, indicating that the natural P. euphratica riparian forest in the lower reaches of the Tarim River has obvious windbreak and sand fixation benefits. ③ The average particle size of sand grains at all heights was 80~93 μm, mainly composed of extremely fine sand. The particle size frequency curve showed a single peak distribution, and the sand dust composition was simple, mainly composed of local sand sources. [Conclusion] The sediment transport on the leeward side of the natural P. euphratica riparian forest in the study area was lower than that of the windward side. Average particle size was smaller and sorting performance was better on the leeward side than on windward side. The average particle size smaller than that of the windward side, the sorting was better than that of the windward side, the kurtosis was narrower than that of windward side, and skewness is slightly smaller than that of the windward side. The P. euphratica riparian forest exhibited obvious windbreak and sand fixation benefits, and can be used as an effective measure to reduce the damage by wind and sand transport in the study area.

Under the influences of climate change and human activities, habitat quality (HQ) in inland river basins continues to decline. Studying the spatiotemporal distributions of land use and HQ can provide support for sustainable development strategies of the ecological environment in arid regions. Therefore, this study utilized the SD-PLUS model, InVEST-HQ model, and Geodetector to assess and simulate the land-use changes and HQ in the Tarim River Basin (TRB) at multiple scales (county and grid scales) and scenarios (SSP126, SSP245, and SSP585). The results indicated that (1) the Figure of Merit (FoM) values for Globeland 30, China's 30 m annual land-cover product, and the Chinese Academy of Sciences (30 m) product were 0.22, 0.12, and 0.15, respectively. A comparison of land-use datasets with different resolutions revealed that the kappa value tended to decline as the resolution decreased. (2) In 2000, 2010, and 2020, the HQ values were 0.4656, 0.4646, and 0.5143, respectively. Under the SSP126 and SSP245 scenarios, the HQ values showed an increasing trend: for the years 2030, 2040, and 2050, they were 0.4797, 0.4834, and 0.4855 and 0.4805, 0.4861, and 0.4924, respectively. Under SSP585, the HQ values first increased and then decreased, with values of 0.4791, 0.4800, and 0.4766 for 2030, 2040, and 2050, respectively. (3) Under three scenarios, areas with improved HQ were mainly located in the southern and northern high mountain regions and around urban areas, while areas with diminished HQ were primarily in the western part of the basin and central urban areas. (4) At the county scale, the spatial correlation was not significant, with Moran's I ranging between 0.07 and 0.12, except in 2000 and 2020. At the grid scale, the spatial correlation was significant, with clear high- and low-value clustering (Moran's I between 0.80 and 0.83). This study will assist land-use planners and policymakers in formulating sustainable development policies to promote ecological civilization in the basin. [ABSTRACT FROM AUTHOR]

Simple Summary: The effects of invasive plants on species diversity and ecosystem stability differ owing to the different stages of invasion. Xanthium spinosum is an invasive weed that is widely distributed in Europe, Asia, and North America. Its adaptability and competitive advantage over native species have led to agricultural loss and biodiversity reduction, yet its impact on local plant communities under different degrees of invasion has not been reported. Therefore, in this study, we aimed to investigate the effects of different degrees of invasion by X. spinosum on the diversity, stability, and invasibility of local plant communities in Yining County, Xinjiang, China. We believe that our study makes a significant contribution to the literature because we found that as the degree of X. spinosum invasion increased, species diversity and community stability decreased, while community invasibility increased. Notably, a light degree of invasion was found to enhance the diversity and stability of local plant communities. Based on our findings, we recommend that X. spinosum be controlled and eradicated in the early stages of invasion to prevent further invasion and harm to indigenous species. Studying the effects of different degrees of exotic plant invasion on native plants' community structure and plant diversity is essential for evaluating the harm caused to ecosystems by plant invasion. In this study, we investigated the effects of Xanthium spinosum, a widespread invasive species, on plant community species diversity and community stability in the Ili River Valley area of Xinjiang, China, under three invasion levels (no invasion and low, moderate, and heavy invasion), and the competitive advantage index, invasion intensity, and contribution of plant community species diversity to community stability and invasibility were determined for the prickly fungus under different degrees of invasion. The results show that there were significant differences (p < 0.05) in the species diversity and community stability of plant communities caused by different degrees of invasion of X. spinosum. The species diversity and stability of plant communities were negatively correlated with the community invasibility, competitive advantage, and invasion intensity of X. spinosum (p < 0.05); therefore, the competitive advantage and invasion intensity of X. spinosum increase with the increase of its invasion degree. On the contrary, community species diversity and stability decreased with the increase of its invasion degree, ultimately leading to differences in community invasibility under different invasion degrees. The Shannon–Wiener and Simpson's indices were the greatest contributors to community stability and invasibility, respectively. Moderate and heavy levels of invasion by X. spinosum reduced the diversity and stability of local plant communities, increased the invasibility of communities, and substantially affected the structures of plant communities. Therefore, the continued invasion by X. spinosum will have an immeasurable impact on the fragile ecosystems and diversity of indigenous species in Xinjiang. We recommend that this invasive species be controlled and eradicated at the early stages of invasion to prevent further harm. [ABSTRACT FROM AUTHOR]

Abstract Environmental flow, one of the main restoration measures for regulated rivers, aims to restore and sustain degraded riparian ecosystems and the human wellbeing that depends on these ecosystems with a reasonable magnitude, frequency, duration and timing of water flow. However, efficacies of environmental flows are often restrained by other demands along the river and inappropriate water management, leading to only spatially limited habitats being suitable for ecosystem functioning. This paper presents current restoration measures in the lower reaches of the Tarim riparian ecosystem in Northwest China and analyzes ecohydrological dynamics as a function of environmental flows. The groundwater level oscillation before/after and during the environmental flows (i.e., manmade water diversion) was examined, and the Mann-Kendall test was applied to identify the overall trend of change in groundwater depth from 2003 to 2011. The growth, distribution, health status (referred to as "vitality") and renewal potentials of the dominant tree species Populus euphratica were quantified by using individual-based repeated measurements of P. euphratica morphology in two sampling sites (a 100-ha permanent plot and five random sampling plots with 50-m radii) at Arghan village in the lower reaches of the Tarim River. Based on these measurements, the effects of restoration measures on the groundwater recharge and the revitalization of degraded trees were assessed. The main contribution and achievements of the water diversion project on rehabilitation of the degraded riparian forests were evaluated; further, the limitations and challenges faced by of the restoration project were examined. The results of this research could help establish a reference for monitoring changes in riparian forests in Central Asia and possibly recommend restoration measures for riparian forest ecosystems in arid regions worldwide. [ABSTRACT FROM AUTHOR]

This study explores a paradigm of sustainable land use in the oases along the Tarim River of northwest China, where a fragile, semi-arid riparian ecosystem is being damaged by excessive land and water use for agriculture, especially for the growing of cotton. The reliance of agriculture on water-demanding cash crops in this region poses a grave threat to survival of the natural Tugai vegetation in the area and to the long-term sustainability of the region. We explored the hypothesis that the species Apocynum pictum (A. pictum), known as Lop-Kendir by locals, and the Chinese red date (Zyzyphus jujube) may act as sustainable crop substitutes for the region, thereby replacing the widely distributed cash crop of cotton that has high water demands. Therefore, we investigated current utilization and cost-revenue structure of these two alternative plants and compared the results to cotton. Three natural resource management types of A. pictum were both identified in the wild and cultivation, with cost-revenue analysis carried out for each. The results show that all three types of institutional arrangements of natural resources, which are namely open access, ranching and farming, were present in our study and at various levels for A. pictum. A. pictum farming costs 16,250.25 yuan/ha, generates 49,014.45 yuan/ha of revenue from raw materials and brings a profit of 32,764.2 yuan/ha, which is the highest of all three cash crops compared. The Chinese government encourages Chinese red date plantations with a "Grain for green" campaign in the Tarim Basin with this plant being more profitable than cotton, which could serve to diversify the region's agriculture. We conclude that A. pictum offers opportunities for the restoration of vegetation in riparian ecosystems on salinized sites under the arid conditions of the Tarim Basin. Furthermore, it can serve as a viable land-use alternative to cotton for cash crop agriculture, as it may generate a certain income in the form of tea and fibers as well as fodder for livestock. [ABSTRACT FROM AUTHOR]

The Tarim River is about 1,320 km long and is one of the longest continental inland waterways in the world. In an undisturbed state, it is accompanied on both sides by floodplain forests of Euphrates poplar ( Populus euphratica Oliv.). The rising water consumption in the upper and middle reaches, and massive hydro-technical interventions in the development of uncultivated land for cotton farming, especially during the last decades, have led to a widespread destruction of the natural ecosystems. This is the case particularly in the lower reaches of the river, where 320 km of the floodplain forests are either highly degraded or dead. Since the year 2000, the Chinese government has made efforts to restore these ecosystems and conducted man-made water diversion project into the affected area. The starting phase of recovering measures needs an efficient and extensive long-term monitoring. A combined approach of remote sensing and terrestrial samples can meet these demands. This study is based on the data from a small-scale ecological monitoring in the past 7 years and combination of QuickBird image information of the floodplain forests along the lower reaches of the Tarim River within the purview of the man-made restoration project. The effects of the artificial water diversion on the dynamics of the groundwater layer and the revitalization of P. euphratica floodplain forests have been analysed in the Arghan transect. The results showed that the groundwater level has risen from 12.6 to 5.5-6.2 m below the surface in the vicinity of the river beds. Some eco-morphological parameters of the P. euphratica trees have different levels of response to the ecological water diversion. To specify, in the vertical direction, the farther the trees are from the river, the weaker the response of ecological indicators. These parameters include tree vitality level, crown diameter, under branch height as well as newly developed crown types of P. euphratica trees. Generally, the floodplain forests within 200 m to the riverbed recovered remarkably, and those between 200 and 800 m from the river showed a medium response to the water transfer, while forests further away than 800 m from the river bed showed less sign of recovery. [ABSTRACT FROM AUTHOR]

The present study examined dust deposition on single leaves of Populus alba var. pyramidalis (Bunge) at various heights (lm, 2m, and 4m), analyzed dust particle size distribution and its contents in arid oasis city Aksu, Northwest China. The results showed that the amount of dust retained per leaf area of P. alba var. pyramidalis (Bunge) differed significantly between sites, as follows: CTA> IA> P> RA> SFA; Leaves at a height of 1 meter retain the most dust compared to other two heights, as follows: lm > 2m > 4m; Dust particles larger than PMio account for more than 90% of all dust particles in all sites and the dust accumulated on tree leaves is mainly of local urban origin; The variation of heavy metal concentrations in different sites is significant. [ABSTRACT FROM AUTHOR]

Carbon management in forests has become the most important agenda of the first half of the 21st century in China in the context of the mitigation of climate change impact. As the main producer of the inland river basin ecosystem in arid region of Northwest China, the desert riparian forest maintains the regional environment and also holds a great significance in regulating the regional/global carbon cycle. In this study, we estimated the total biomass, carbon storage, as well as monetary ecosystem service values of desert riparian Populus euphratica Oliv. in the lower reaches of the Tarim River based on terrestrial forest inventory data within an area of 100 ha (100 plots with sizes of 100 m × 100 m) and digitized tree data within 1000 ha (with 10 m × 10 m grid) using a statistical model of biomass estimation against tree height (TH) and diameter at breast height (DBH) data. Our results show that total estimated biomass and carbon storage of P. euphratica within the investigated area ranged from 3.00 to 4317.00 kg/ha and from 1.82 to 2158.73 kg/ha, respectively. There was a significant negative relationship (p < 0.001) between biomass productivity of these forests and distance to the river and groundwater level. Large proportions of biomass (64% of total biomass) are estimated within 200 m distance to the river where groundwater is relatively favorable for vegetation growth and biomass production. However, our data demonstrated that total biomass showed a sharp decreasing trend with increasing distance to the river; above 800 m distance, less biomass and carbon storage were estimated. The total monetary value of the ecosystem service “carbon storage” provided by P. euphratica was estimated to be $6.8 × 104 USD within the investigated area, while the average monetary value was approximately $70 USD per ha, suggesting that the riparian forest ecosystem in the Tarim River Basin should be considered a relevant regional carbon sink. The findings of this study help to establish a better understanding of the spatial distribution pattern of P. euphratica forest under water scarcity and can also provide an alternative approach to local decision-makers for efficient and precise assessment of forest carbon resources for emission reduction programs. [ABSTRACT FROM AUTHOR]

Iris ruthenica Ker-Gawl. (Russian iris) is a perennial, clonal, herbaceous plant that is spread across the degraded mountain grasslands in northern Xinjiang. In this study, to explore the breeding system and the impact of slope orientation on the flowering phenology, pollination characteristics, and other aspects of I. ruthenica , we used a combination of field observations and controlled experiments to compare the population density, flowering phenology, floral characteristics, breeding system, and pollinator type and behavior of plants on different slope orientations. Vegetation coverage on the north (N), southwest (SW), and southeast (SE) slopes was 90%, 67%, and 53%, respectively. Differences in plant height and diameter were observed between the SE slope and the N and SW slopes, whereas the N and SW slopes were similar in these respects. The SE slope exhibited the earliest initial flowering time, followed by the SW and N slopes. The diameter of the corolla, distance between the stigma and anther, length of the anther and ovary, number of pollen grains, and number of ovules on the N slope were smaller than those on the SE and SW slopes, whereas those of the SE and SW slopes were similar. Artificial pollination experiments showed that neither bagging nor unbagging resulted in seed formation after emasculation for all slope orientations. The pollinating insects of I. ruthenica included Bombus sp., Amegilla leptocoma , Andrena sp., and Halictus sp.; the types and numbers of pollinating insects differed among slopes. In summary, on SE and SW slopes with high temperatures and sufficient sunlight, this species attracted pollinators and provided them with more opportunities to visit and pollinate by flowering early, with large numbers of blooms, and a longer flowering period and lifespan, ensuring successful reproduction. Under unfavorable conditions, such as insufficient pollinators and limited activity caused by the more stressful environmental conditions of the N slope (including low temperature and insufficient light), this species ensures a certain seed yield by increasing its self-compatibility., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tayier, Hasimu, Aishan and Yimingniyazi.)