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Aims Sand-fixing shrub Salix gordejevii plays an important role in sand dune stabilization but often shows severe decline and mortality on the windward slopes of active dunes. The objective of this study was to explore the environmental drivers and physiological mechanisms behind its decline and mortality on the windward slopes of active sand dunes. Methods The xylem hydraulics, sap flow, water relations and non-structural carbohydrate reserves were measured for S . gordejevii plants that respectively inhabited interdune, leeward and windward positions of active dunes with contrasting soil water regimes. Results Root exposure caused by wind erosion, rather than low soil moisture, predisposed windward S . gordejevii plants to stronger water stress. Correspondingly, the windward plants showed reduced transpirational water use and exhibited a suite of acclimative adjustments in leaf traits favoring water conservation. Despite these adjustments, windward S . gordejevii plants still suffered from higher risks of hydraulic failure and branch mortality. No evidence of carbon depletion in windward S. gordejevii plants was found although the soluble sugar to starch ratios changed significantly. Conclusions Our findings suggest that wind-erosion-induced root exposure triggers water stress and eventually causes the mortality of windward S . gordejevii plants, during which increased risk of hydraulic dysfunction is pronounced.

Background Understanding the dynamics of species and functional diversity and their interrelationships during vegetation restoration is essential for assessing the effectiveness of ecosystem restoration. Yet, the mechanistic links between species diversity and functional diversity during vegetation restoration remain uncertain, with community-level functional traits likely mediating this relationship. Methods We studied a chronosequence of Artemisia ordosica -dominated dryland communities, including semi-fixed (D1), fixed (D2), soil-biocrusted fixed (D3), and shrub-herbaceous-fixed sand-dunes (D4). Thirteen leaf functional traits were measured, including leaf tissue density (LTD), and leaf dry matter content (LDMC). Community-weighted mean leaf functional traits (CWM-LFTs) were calculated using importance value-weighted averages. Results Species and functional diversity increased progressively from stages D1 to D4, with the coefficient of variation for CWM-LFTs ranging from 7.71% to 57.27%. Changes in species diversity during sand dune stabilization were linked to a strategy of slow growth and cumulative increases in LTD, LDMC, and leaf carbon content (LCC), improving the community’s physical defense and nutrient retention. Leaf structural traits mirrored diversity patterns, with LDMC most strongly linked to functional evenness, functional divergence and Rao’s quadratic entropy. Conclusions Our results show that both species and functional diversity increased progressively with sand-dune stabilization. The plant community followed a trajectory of increasingly complex strategies, shifting from stress-tolerant traits toward competition-adapted traits in later stages. The LDMC was strongly correlated with both species and functional diversity, serving as a key trait that mediates competitiveness and defense in resource-limited ecosystems. These findings highlight the importance of trait-based assembly in vegetation restoration and offer new insights for desertification control.

Martínez, M.L.; Landgrave, R.; Silva, R., and Hesp, P., 2019. Shoreline dynamics and coastal dune stabilization in response to changes in infrastructure and climate. In: Silva, R.; Martínez, M.L.; Chávez, V., and Lithgow, D. (eds.), Integrating Biophysical Components in Coastal Engineering Practices. Journal of Coastal Research, Special Issue No. 92, pp. 6–12. Coconut Creek (Florida), ISSN 0749-0208. The goal of this study was to understand shoreline dynamics and coastal dune stabilization in response to changes in infrastructure (urbanization and the construction of breakwaters for shoreline protection) and climate in Playa Chachalacas, located in the central region of the Gulf of Mexico. Aerial images from different years were analysed to examine: (a) shoreline dynamics and changes at the river mouth, located down-drift from the dunefield; (b) stabilization of the mobile dune; and (c) urbanization along the shoreline. The data show that the cover of grasses and shrubs increased rapidly on the dunefields. In some areas, there was intense erosion along the shoreline and accretion in others at significant rates. The breakwaters promoted accretion but exacerbated erosion down-drift, with notable changes in the inlet. Finally, urbanization has occurred at a fast rate, and mostly parallel to the shoreline. The results indicate that different factors affect sediment dynamics: (a) the breakwaters solved the erosion problem locally but generated intense erosion down-drift; (b) warm and wet climate promoted vegetation growth and sediment stabilization; and (c) urbanization along the coast resulted in ecosystem loss and increased risks to flooding. Indeed, management and development plans for coastal environments need to consider the dynamic nature of the coastline.

Pines are widely planted for sand dune stabilization and their cultivation results in the changes in physical, chemical, hydro-physical and water repellency properties. Soil properties were evaluated at three Scots pine plantations (PF1, PF2 and PF3) close to Studienka village, Borská nížina lowland (southwestern Slovakia) during hot and dry summer period. The PF1 site is a newly established plantation, the PF2 site is about 30 years old plantation, and the PF3 site is about 100 years old plantation. Here, we estimated the differences in pH, soil organic carbon content, C , particle size distribution, PSD, saturated, s, and unsaturated, (–2 cm), hydraulic conductivity, water, , and ethanol, , sorptivity, water drop penetration time, WDPT, and repellency index, RI. It was found that C varies most significantly with plantation age, and relative differences in PSD and pH were lower than the relative difference in C . The PF3 site differs the most from the other two, especially in C and in the content of sand fraction. It can be attributed to the older age of the plantation, which represents a more advanced stage of succession accompanied by an accumulation of soil organic matter. Relationships between C , (–2 cm), RI, and WDPT and pine forest age were described by appropriate mathematical models. We found a similarity between (–2 cm) and RI relationships vs. pine forest age (exponential models), and between Cox and WDPT relationships vs. pine forest age (first and second-order polynomial models). The latter similarity can be supported by the fact that soil water repellency is induced by the hydrophobic and amphiphilic components of soil organic matter.

Rising temperatures and precipitation are important climate change processes around the world. The responses of plants to these trends are still unclear in semi-arid regions, especially in areas with degraded sandy grassland. To provide insights into the response in these regions, we investigated responses of vascular plants to warming and increased precipitation in mobile dunes, fixed dunes and grassland, which represent the series of sand dune stabilization by plants in semi-arid northeastern China. Plant biomass, especially the aboveground biomass, varied significantly ( P  < 0.05) among dune categories. Total plant density in the fixed dunes and grassland was 1.9 and 1.7 times that in the mobile dunes. Species richness differed slightly but significantly ( P  < 0.05) among the habitats. Increasing precipitation in a drought year (65.5% of the long-term average annual precipitation) by 30% did not significantly affect any plant variable. By contrast, warming significantly decreased the belowground biomass, total biomass, species richness and plant total density. In summary, in semi-arid region with sandy soil, additional precipitation slightly improved plant performance, but increased temperature decreased plant performance. Soil texture, which determines the balance between moisture retention and evaporation, may be a key factor in determining these responses when precipitation is unusually low.

Artemisia ordosica is an excellent sand-fixing shrub for sand stabilization in northwestern China. Sand dune stabilization, a critically important process, leads changes in abiotic factors, such as soil structure and nutrient contents. However, the effects of factors on an A. ordosica community following sand stabilization remain unclear. In this study, we used canonical correspondence analysis （CCA） to examine the relationships between A. ordosica communities and environmental factors at three habitats： semi-fixed dune （SF）, fixed dune with low-cov- erage biological soil crust （F）, and fixed dune with high- coverage biological soil crust （FC） in Mu Us desert. The mean height and coverage of plants increased with sand stabilization, while species diversity and richness increased initially and then reduced significantly. Correlation analysis and CCA revealed that slope, soil organic carbon, and nutrient contents, proportion of fine soil particles, soil moisture, and thickness of biological soil crust were all highly correlated with vegetation characteristics. These environmental factors could explain 40.42 % of the vege- tation-environment relationships at the three habitats. The distribution of plant species was positively related to soil moisture in the SF dune. Soil moisture, soil nutrient, and fine-particle contents mainly affected plants distribution in the F dune. In the FC dune, distribution of plant species was positively and negatively correlated with the thickness of biological soil crust and soil moisture at a depth 0-20 cm, respectively. The dominance value of typical steppe species increased significantly following sand-dune stabilization and relations between species and samples in CCA ordination bi-plots showed that perennial grasses could invade the A. ordosica community on FC, indicating A. ordosica communities had a tendency to change into typical steppe vegetation with the further fixation. We conclude that the significant differentiation not only occurred in community characteristics, but also in the relationships between vegetation and environmental factors among the three stages of dune fixation. So, restoration of degraded dune ecosystems should be based on habitat conditions and ecological needs.

During the process of dune vegetation restoration, understanding how grazing disturbance affects the relationship between plant species is a critical issue in ecological studies. However, there is insufficient evidence on the changes in the interaction between dominant shrubs and understory vegetation under grazing behavior. We aimed to study how grazing and dune stabilization affects the relationship between Caragana microphylla and understory vegetation. We established fencing at various stages of dune stabilization and proceeded to compared the performance indicators (e.g., richness and biomass) and the relative interaction index of understory vegetation and different functional groups along the dune stability under grazing and fencing conditions. Results showed that C . microphylla had facilitation on understory plants, and increased with dune stability, while the facilitation of Caragana microphylla on understory vegetation was stronger under grazing conditions. As sand dune stabilization increases, the facilitation of C . microphylla on understory vegetation diversity decreases significantly. However, there was no significant difference in the facilitation of C . microphylla on understory vegetation biomass at different stages of sand dune stabilization. This is related to the survival strategy of perennials being less tolerant to environmental stress than annuals, because grazing increased the richness of both annuals and perennials while reducing the overall biomass, and in the later stages of sand dune stabilization, and the facilitation of C . microphylla on perennials was higher than on annuals. Our study highlights the importance of the responses of different life-form groups to environmental factors and grazing disturbance during the process of sand dune vegetation restoration, as they play a crucial role in shaping the development of the relationship between understory vegetation and dominant shrubs.

Coastal dunes, in particular foredunes, support a resilient ecosystem and reduce coastal vulnerability to storms. In contrast to dry desert dunes, coastal dunes arise from interactions between biological and physical processes. Ecologists have traditionally addressed coastal ecosystems by assuming that they adapt to preexisting dune topography, whereas geomorphologists have studied the properties of foredunes primarily in connection to physical, not biological, factors. Here, we study foredune development using an ecomorphodynamic model that resolves the coevolution of topography and vegetation in response to both physical and ecological factors. We find that foredune growth is eventually limited by a negative feedback between wind flow and topography. As a consequence, steady-state foredunes are scale invariant, which allows us to derive scaling relations for maximum foredune height and formation time. These relations suggest that plant zonation (in particular for strand “dune-building” species) is the primary factor controlling the maximum size of foredunes and therefore the amount of sand stored in a coastal dune system. We also find that aeolian sand supply to the dunes determines the timescale of foredune formation. These results offer a potential explanation for the empirical relation between beach type and foredune size, in which large (small) foredunes are found on dissipative (reflective) beaches. Higher waves associated with dissipative beaches increase the disturbance of strand species, which shifts foredune formation landward and thus leads to larger foredunes. In this scenario, plants play a much more active role in modifying their habitat and altering coastal vulnerability than previously thought.

Sand dune encroachment poses a significant environmental challenge for peri-urban and rural communities in the North African desert, which is home to more than one-third of the region’s population. The continuous movement of sand dunes disrupts residential development, infrastructure, and agricultural systems, threatening food and energy supplies in regions already sensitive to climate variability. The subsequent decline in habitability in such areas often leads to external migration, which triggers heightened socioeconomic and geopolitical instability. As part of the North African Sahara, the West El-Minya Governorate in Egypt is a crucial case study for Saharan areas where growing dune encroachment compromises extensive and critical agricultural developments. We investigate and quantify the primary drivers of sand movement, including wind speed and direction, surface elevation, slope, land use, vegetation cover, and soil cohesion, through the Sand Dune Encroachment Vulnerability Index. Our results reveal that agricultural soils with inadequate irrigation, particularly those adjacent to bare lands, are most susceptible to encroachment. Furthermore, 14% of the total cultivated area is affected by dune encroachment, resulting in estimated annual economic losses of $263 million. Moreover, ~42% of newly established agricultural lands are situated in zones of very high vulnerability, with anticipated productivity reductions of 25% and annual rehabilitation costs approximately $52 million. Transport infrastructures are also impacted, with key highways incurring $6.5 million annually in sand clearance due to recurring dune interference. The proximity of dune-encroached areas to irrigation canals escalates sedimentation rates, deteriorating water quality and incurring additional dredging expenses of $31.3 million per year, with adverse repercussions for agriculture and fisheries. Our study reveals growing dune encroachment, highlighting the urgent need for targeted, nature-based dune stabilization interventions, such as dune leveling and reclamation, in peri-urban Saharan regions. These measures are crucial for preventing further land degradation, reducing population displacement and regional conflict risks, and maintaining the habitability of arid areas.

This study systematically investigates the influence of cementation solution concentration on the sand fixation effect induced by palm fiber-enhanced microorganisms through microbial induced calcium carbonate precipitation (MICP), aiming to optimize its application in ecological restoration and engineering reinforcement. A series of experiments including unconfined compressive strength tests, direct shear tests, permeability tests, nuclear magnetic resonance analysis, calcium carbonate content determination, scanning electron microscopy (SEM), and X-ray diffraction (XRD) evaluates the mechanical properties, permeability, and microstructural characteristics of MICP-treated sand under varying cementation concentrations ranging from 0.2 to 0.7 mol/L. Results show that a concentration of 0.5 mol/L yields the best mechanical performance, with significantly higher unconfined compressive strength (666.65 kPa) and shear strength compared to other concentrations. At lower concentrations from 0.2 to 0.4 mol/L, increasing the concentration enhances calcium carbonate deposition, which improves mechanical properties and reduces both permeability coefficient and porosity. In contrast, higher concentrations above 0.5 mol/L inhibit microbial enzymatic activity, leading to reduced calcium carbonate content and mechanical strength, along with increased permeability and porosity. Microscopic analysis reveals that at 0.5 mol/L, calcium carbonate crystals form densely and uniformly, effectively filling pore spaces and strengthening inter-particle bonding. Therefore, 0.5 mol/L represents an optimal balance between performance and cost, reducing resource waste while ensuring mechanical enhancement and supporting applications in sand dune stabilization, windbreaks, sand fixation, and ecological vegetation restoration.