Biological soil crusts (BSCs) are the main active groundcover community in arid regions. BSCs can significantly affect the material cycle and energy exchange, improve the physical, chemical, and biological properties of surface soil, and influence the soil multifunctionality (SMF). Moss crust is an important type of BSCs. This study investigates the SMF variability of moss crust-covered and bare sand in the deserts of northwestern arid regions, and explored the main drivers of the variability. We analyzed eight crucial ecosystem function indicators. SMF was calculated by applying the mean method and factor analysis approach. We used the ordinary least square and structural equation modeling to explore the drivers of SMF changes. The results show that: (1) soil monofunctionality and SMF under moss crust cover were higher than those in bare sand (P<0.05). (2) The drivers of the SMF change in bare sand and under moss crust cover were very different. The main drivers of SMF in bare sand were aridity and soil water content, whereas the driver of SMF under moss crust cover was soil sand content (Sand). (3) The mean annual temperature had the largest indirect effect on changes in SMF for both soil in bare sand and under moss crust cover. Therefore, the development of moss crust significantly increased SMF and, in addition, modulated the relevant drivers of SMF. Our results are important for a deep understanding of the differences and drivers of SMF in desert soil with bare sand and under moss crust cover.

This study aimed to reveal the effects of different habitats and substrates on seed germination and seedling growth of Malus sieversii after passing through digestive tract of cattle. A controlled experiment was set up in field based on the different habitats and substrates in which seeds were deposited after passing through the digestive tract of cattle. The three habitats were as follows: forest edges, gaps, and understory. The four treatments were as follows: W (seeds through digestive tract+intact feces), P (seeds through digestive tract+broken feces), T (seeds through digestive tract+soil), and control C (seeds not through digestive tract+soil). The results showed that: The seed germination rates, seedling survival rate, and seedling biomass of M. sieversii were significantly different (P<0.05) in different habitats and treatments. In the forest edge habitat, seeds germinated rate was higher in soil substrate compared to fecal substrate, while the gaps and understory habitats showed the opposite trend. Seedling survival rate was significantly higher in the forest edge and gaps habitats compared to the understory habitat. Under the same treatment, seedling biomass was higher in the forest edge compared to the gaps, and higher in the gaps compared to the understory. Within the same habitat, seedling biomass from fecal substrate in forest edge and gap habitats surpassed that of soil substrate. The study revealed that the heterogeneity of habitat and substrate is the main reason that affects the seed germination and seedling establishment of M. sieversii after passing through digestive tract of cattle.

Seed germination and the seedling growth of sand-fixing plants are decisive aspects of land desertification management, and soil moisture is the main limiting factor affecting these aspects. In this study, we compared and analyzed the seed germination of three sand-fixing plants under different moisture gradients (4%, 6%, 8%, 10%, 15%, 20%, and 25%) in an indoor potting experiment using Hedysarum scoparium, Caragana korshinskii, and Artemisia desertorum to investigate the response of seed germination and seedling growth of sand-fixing plants to changes soil in moisture. The results showed that: (1) significant differences (P<0.05) were observed in the seed germination characteristics of the three sand-fixing plants as the soil moisture increased. The germination rates tended to increase and then decrease as the soil moisture increased. C. scoparium had the highest germination rate at 15% and 20% soil moisture (83.00% in both); C. korshinskii had the highest germination rate at 10% soil moisture (73.00%); and the seed germination rate of A. desertorum reached the maximum value of 77.50% at 15% soil moisture, and then slowly decreased, although the change was not significant. (2) The leaf area and root length of the three plants showed tended to first increase and then decrease as the soil moisture increased, and the specific leaf area and root:crown ratio tended to decrease and then increase. (3) The highest biomass of C. scoparium, C. korshinski, and A. desertorum seedlings was 0.0733 g, 0.1142 g, and 0.0363 g at 10%, 8%, and 20% soil moisture, respectively, and the aboveground biomass was significantly higher than the belowground biomass (P<0.05), although the allocation of belowground biomass by C. korshinski seedlings was higher than that of C. scoparium and A. desertorum. (4) The SOD activity, POD activity, CAT activity, Pro content, SS content, and Chl content of the three sand-fixing plants tended to increase and then decrease as the soil moisture increased, whereas the MDA content, membrane permeability, and relative water content tended to decrease and then increase. Based on the above results, it was concluded that the three sand-fixing plants of C. scoparium, C. korshinski, and A. desertorum had the best seedling growth at 15%, 8% and 8% soil moisture, respectively, through the analysis of the affiliation function method. Therefore, when these three sand-fixing plants are used for vegetation restoration, the changes in soil moisture caused by rainfall conditions should be fully considered in addition to the seeds’ own traits to improve the seedling emergence rate and the success of seedling growth.

In the present study, clay sand barrier-artificial Haloxylon ammodendron plantations and a mobile sand site (control) in the Minqin desert area were used to investigate the plant species composition, species importance value, dominant species characteristics, species diversity, and soil moisture content. This study explored the long term effects of clay sand barrier-artificial Haloxylon ammodendron plantation construction on regional plant community structure, species diversity, and soil moisture. In total, 12 species belonging to 12 genera and 6 families were recorded in the clay sand barrier-artificial Haloxylon ammodendron plantations in the Minqin desert area, with Chenopodiaceae and Zygophyllaceae being the dominant families. The construction of the artificial sand control system significantly increased the number of plant species in the region (from 4 species to 5-8 species). With an increase in the installation period, the vegetation structure gradually evolved from Agriophyllum squarrosum and Haloxylon ammodendrine (dominant species) to Grubovia dasyphylla, Kali collinum, Limonium aureum, and Haloxylon ammodendrine (dominant species). The life forms also shifted from a single type dominated by annual herbaceous plants to a composite type consisting of annual herbaceous plants, perennial herbaceous plants, and shrubs. Regarding alpha diversity, species richness index, Shannon-Wiener index, Simpson index, Pielou index, and Alatalo index showed an overall unimodal trend, with the highest species number and most even species distribution observed in the 20-year installation site and the lowest species number and most uneven species distribution observed in the control sand site. The Jaccard index of plant community similarity between neighboring sites with various installation periods showed the following order: control sand site > 1-year installation site > 20-year and 40-year installation sites > 1-year and 5-year installation sites > 10-year and 20-year installation sites > 40-year and 60-year installation sites > 5-year and 10-year installation sites. The dissimilarity index and Cody index showed the opposite trend. The fluctuation pattern of the regional soil moisture content was consistent with the trend of plant community succession. Compared with deeper soil layers (40-60 cm), the role of shallow soil layers (10-30 cm) in the natural succession process of regional plants was more pronounced.

In the context of global climate change, the spatiotemporal characteristics of fractional vegetation coverage (FVC) serve as a crucial indicator for assessing ecological environment quality in various regions. However, the specific spatiotemporal variations, change trends, and underlying mechanisms of FVC response to human activities in Inner Mongolia remain undefined. Bridging this knowledge gap is essential for understanding ecological management outcomes and providing a scientific basis for local ecological policies and spatial planning. Using MOD13A1 NDVI data, land cover data, and nighttime light data spanning from 2000 to 2022, we calculated the annual maximum fractional vegetation coverage in Inner Mongolia and explored its spatiotemporal variations. Additionally, we illustrated the change trends in FVC. We conducted pixel-by-pixel correlation analysis to examine the response modes of FVC to human activities. Our findings reveal the following: (1) FVC distribution in Inner Mongolia demonstrated a decreasing trend from northeast to southwest, consistent with the overall precipitation changes in China. Notably, areas along the Yellow River, such as the Houtao Plain and the Qiantao Plain, exhibit relatively higher FVC due to abundant water resources and well-developed agriculture. Overall, FVC showed improvement with a growth rate of 0.0039·a^-1, remaining relatively stable in most areas (64.02%) and significantly increasing in 31.64% of the region, all prefecture-level cities showing a positive average annual growth. (2) Changing trends in FVC were predominantly nonsignificant (65.62%), followed by a significant increase (17.36%), an extremely significant increase (13.43%), a significant decrease (3.27%), and an extremely significant decrease (0.32%). Regions experiencing significant and highly significant reductions displayed a strong spatial correlation with newly developed construction land. (3) Regarding human activities in Inner Mongolia, most regions (79.67%) showed no significant influence on FVC changes. In 12.80% of the regions, human activities positively impacted FVC, primarily in grassland and arable land areas surrounding urban zones. Conversely, 7.53% of the regions demonstrated a negative impact of human activities on FVC, chiefly in areas undergoing land cover transitions from arable land to construction land and newly added industrial and mining zones. While most regions showed no significant correlation between FVC variation and human activities, this does undermine the impact of ecological protection policies implemented in China like the “Ecological Protection Red Line” and “Arable Land Red Line.” The effectiveness of these measures lies in preventing land type conversion, such as grassland and arable land to other categories. This not only maintains the stability of FVC within protected areas but also regulates the intensity of human activities. However, the outcomes of these measures are not adequately reflected in nighttime light data. Therefore, while nighttime light data partially reflect the influence of human activity intensity on FVC, its limitations must be fully recognized in the comprehensive evaluation of ecological protection policies.

Based on Landsat imagery data from 2001 to 2021, the NDVI and image dichotomous model were used to estimate vegetation cover and explore the spatial and temporal trends and driving forces of vegetation cover in the Ulan Buhe Desert along the Yellow River. This study aimed to provide a theoretical basis for the restoration of vegetation in the Ulan Buhe Desert along the Yellow River and the selection of key areas for future ecological construction. The results showed that (1) the overall vegetation cover in the study area showed a fluctuating upward trend, and the vegetation restoration status was good. The average vegetation cover increased from 0.294 to 0.526, and this increase was most evident from 2007 to 2017. (2) From 2001 to 2021, the transformation of areas regarding levels of vegetation cover in the Ulan Buhe Desert along the Yellow River was more frequent where large areas of 102.00 km² and 128.82 km², respectively, transformed from low and lower vegetation cover to medium and higher vegetation cover, respectively. In addition, the vegetation cover in 42.1% of the study area tended to increase significantly, mainly in the near Dengkou section, whereas that in 4.90% of the area tended to decrease significantly, mostly near the Wuhai section, which should be the key area of concern in future ecological restoration efforts. (3) The spatial variability of vegetation cover in this area is mainly driven by human activities and climate factors. The interaction between the driving factors is mainly enhanced by two factors, among which the key interaction factors with the highest degree of influence are land use type and annual average temperature. In this study, the dynamic change characteristics and driving forces of vegetation cover in the Ulan Buhe Desert along the Yellow River were studied in a systematic and stepwise manner, providing theoretical and empirical support for desertification control, rational land use and high-quality development in the study area.

Water use efficiency (WUE) is an important measure of the tradeoff between photosynthetic carbon sequestration and water consumption in ecosystems. Estimation of vegetation’ WUE and analysis of the spatiotemporal distribution of vegetation WUE are crucial for ecosystem preservation as well as the wise use and development of water resources in this area. In this study, we assessed the spatial and temporal characteristics of vegetation WUE and its main influencing factors in Salt Lake County from 2000 to 2019 on the basis of GPP and ET data from MODIS. The results were as follows: (1) Both ET and GPP increased significantly from 2000 to 2019 (P<0.01), and the rates of increase were 7.61 mm·a^-1 and 7.23 g C·m^-2·a^-1, respectively. ET and GPP showed obvious heterogeneity in space. (2) Between 2000 and 2019, the vegetation WUE in Yanchi County fluctuated between 0.80 and 1.11 g C·kg^-1·H₂O, and the multiyear average value was 0.91 g C·kg^-1·H₂O. The rate of increase was 0.0013 g C·kg^-1·H₂O·a^-1, but it was not significant. The vegetation WUE showed high heterogeneity in space, with high values mainly distributed in the northeast and low values in the southwest. (3) From 2000 to 2019, WUE mainly increased and decreased in 54.70% and in 45.30% of the area, respectively, in Yanchi County. In the future, 61.48% of the area in Yanchi County will show the same change trends in WUE as in the past, and 38.52% of the area will show reversed trends in WUE. (4) The WUE of each land use type in different study periods decreased in the following order: forest land > cultivated land > grassland. (5) There was a significant correlation between WUE and GPP in Yanchi County (P<0.05), whereas variations in GPP were mainly driven by changes in ET, NDVI, and precipitation, indicating that GPP is the main reason for the changes in WUE in Yanchi County. The Yanchi County Ecological Restoration Project not only enhances vegetation productivity but also increases regional water consumption, resulting in fluctuations in the WUE of the regional ecosystem. This suggests that vegetation restoration in Yanchi County has intensified regional water depletion while enhancing vegetation productivity, which provides a theoretical basis for future ecological revegetation and codevelopment of water resources in Yanchi County.

This study investigated the impact of soil microbial film sand fixation on the photosynthetic and fluorescence characteristics of seedlings from two psammophyte species, Ammopiptanthus mongolicus and Astragalus laxmannii. A pot experiment was conducted utilizing different application methods (spray, mix) and application amounts (0, 1, 3, 5, 7, and 10 g·kg^-1). After soil microbial biofilm formation, the characteristics of plant gas exchange and chlorophyll fluorescence were analyzed. The results showed that: (1) An application of bacteria exceeding 3 g·kg^-1 notably increased the hardness and thickness of the consolidated layer, alongside higher soil urease and sucrase activities compared to the control group (P < 0.05). (2) The net photosynthetic rate of Astragalus laxmannii in 3-7 g·kg^-1 treatment was significantly higher than that of the control (P < 0.05). Additionally, its transpiration rate, net photosynthetic rate, and intercellular CO₂ concentration surpassed those of Ammopiptanthus mongolicus (P < 0.05). (3) Astragalus laxmannii treated with over 5 g·kg^-1 displayed significantly higher F_v/F_m values compared to the control group (P < 0.05). Except for the 3 g·kg^-1 treatment, Ammopiptanthus mongolicus exhibited higher F_v/F_m and Q_P values than Astragalus laxmannii. (4) Soil properties, photosynthetic gas exchange, and chlorophyll fluorescence were partially mediated models. Changes in soil characteristics can directly affect the chlorophyll fluorescence characteristics of Ammopiptanthus mongolicus and Astragalus laxmannii. The soil microbial film increased consolidation layer hardness and thickness by 3.84% and 152.85%, respectively, and enhanced catalase, urease, and sucrase activities by 93.37%, 170.68%, and 256.03%, respectively. This improvement in soil quality and leaf stomatal conductance enhanced photosynthetic efficiency and capacity in both plants. The net photosynthetic rate and F_v/F_m increased by 28.48% and 0.84%, respectively.

Mathematical modeling is an important method for estimating shrub biomass. In this study, two desert shrubs, Reaumuria soongarica and Sympegma regelii, commonly found in the Piedmont belt of the northern slopes of the mid-Kunlun Mountains, were observed. The whole-plant harvesting method was employed, and plant height (H), canopy area (S), and plant volume (V) were used as independent variables. Plant above-ground biomass (W₁), below-ground biomass (W₂), and whole-plant biomass (W₃) were used as dependent variables to establish the function model. The selection of optimal biomass estimation models for these two desert shrubs was based on the largest determination coefficient (R²), smallest estimated standard deviation (SEE), and significance level (P < 0.001). The results indicated that quadratic function models were optimal for estimating biomass in both R. soongarica and S. regelii, except for the whole-plant optimal prediction model of S. regelii, which followed a linear function. For R. soongarica, the highest correlation was observed between plant volume (V) and biomass, with R² ranging from 0.820 to 0.920. For S. regelii, the highest correlation was between canopy area (S) and biomass, with R² ranging from 0.935 to 0.973. All optimal models for biomass estimation in R. soongarica and S. regelii passed the significance test (P<0.001), with fit rates ranging from 84.1% to 95.6%. These models were deemed reliable for biomass estimation. The outcomes of this study can offer valuable insights for studying carbon stocks and evaluating carbon sink potential in desert ecosystems.

In nutrient-limited environments, apoplastic decomposition is a critical biogeochemical process for carbon (C) and nutrient cycling. Apoplastic decomposition and nutrient release processes are particularly important in arid and extremely arid regions, where deserts and dryads are the dominant ecosystem types. These processes play a crucial role in stabilizing soil, improving texture, and replenishing soil fertility due to the dearth of nutrients and organic matter in the soil. Plant nutrient uptake efficiency in such soil primarily relies on the decomposition of apoplastic material. In extremely arid desert regions like the Taklamakan Desert, apoplastic burial by quicksand is common, yet the complexities and characteristics of apoplastic decomposition under sand burial remain relatively unknown. To characterize the decomposition and nutrient dynamics of apomictic material in desert highway shelterbelt forest strips, we studied assimilated Haloxylon ammodendron and Calligonum arborescens assimilated branches, along with Tamarix ramosissima leaves, under surface exposure and sand burial treatments 510 days. Additionally, decomposition tests were conducted using the apoplast net bag method. The results showed that: (1) There were significant differences in mass loss between exposed and sand-buried treatments for the three plant species, with higher mass loss of apomictic material under sand burial. By the end of the decomposition test, the weight loss rates of Haloxylon ammodendron, Calligonum arborescens, and Tamarix ramosissima under the exposed treatment were 7%, 6.8%, and 18.1%, respectively, and those of pike, arborvitae, and multi-branched tamarisk under the sand-buried treatment were 23.7%, 9.7%, and 21.9%, respectively. (2) During the decomposition process, changes in apoplastic C, N, and P contents under the two treatments were inconsistent. The N and P contents of Haloxylon ammodendron and Calligonum arborescens assimilated branches showed a net enrichment, while the C content demonstrated net release. Similarly, the N and P contents of leaves of multi-branched Tamarix ramosissima displayed net enrichment and net release, respectively, while the C content had an enriched-released state. (3) Olson’s exponential decay model was employed to analyze the decomposition process and fit the mass residual rate of the apoplastic material. The decomposition coefficients’ k values for the apoplastic material of the three plants were ranked as follows: sand-buried treatment > bare treatment; (4) An analysis of the k values of the apoplastic material and the related factors showed that the initial N, P, C:N, and C:P contents of the apoplastic material had a significant effect on the rate of decomposition (P < 0.01). These results indicate that sand burial significantly influences the decomposition process of apomictic litter in desert highway protection forests within extremely arid zones.

Exploring the response of leaf and root morphological characteristics of desert plants to drought stress is helpful in understanding and predicting their growth regulation strategies under the climate change scenario. The seedlings of the typical desert plant Caroxylon passerinum were treated with slow and rapid drought, and the morphological indices of leaves and roots were measured. The morphological characteristics of leaves and roots of C. passerinum seedlings under drought stress were analyzed using slow and fast drought treatments. The results showed that: (1) with an extension in slow drought stress treatment time, thick-root diameter, fine-root specific length, and specific root area decreased; the leaf tissue density under rapid drought treatment increased; after slow drought treatment, the thick-root tissue density increased, while it increased at first and then decreased post-rapid drought treatment. (2) At the end of the growth period of 54 days, the thick-root diameter reduced markedly under the two treatments; the succulent degree and water content were significantly lower under rapid drought than those of the control and slow drought treatments, respectively. The thick-root tissue density of C. passerinum seedlings increased significantly after 37 days of stress, which was higher post-slow than fast drought. (3) The first four axes of principal components were mainly affected by coarse-root specific root length, thick-root tissue density, fine-root specific root length, and specific leaf area. Correlation analysis revealed that 29 pairs of characters were interrelated. In summary, the leaves, thick roots, and fine roots of C. passerinum showed varying adaptation strategies especially by reducing the diameter of thick roots under the two types of drought treatment. Under rapid drought, C. passerinum adapted to soil water deficit by enhancing the leaf tissue density and reducing fine-root specific root length and specific root area. Thus, C. passerinum seedlings adapt to drought through a coordination or tradeoff within and between leaf and root traits.

To understand the relationship between C, N, and P contents of the leaves of desert plants and soil environmental factors, 14 desert plant communities in high and low water or salt environments in Xinjiang Ebinur Lake Nature Reserve were used as research subjects. The C, N, and P contents of the leaves were determined, their stoichiometric ratio, homeostasis characteristics, and their relationship with soil environmental factors were discussed. The results showed that: (1) There were significant differences in soil organic carbon (SOC), total N (TN), C:N, C:P, N, and P contents of leaves under varying water-salt environments. (2) Pearson correlation analysis revealed that the leaf C:P demonstrated a significant negative correlation with soil conductivity (EC), SOC, C:N, and C:P (P<0.05). Leaf C was remarkably negatively correlated with soil C:N (P<0.05). Leaf P was positively correlated with soil SOC and C:N; leaf N was positively correlated with soil C:N; and leaf C:N was positively associated with soil TN (P<0.05). Leaf P was positively correlated with soil C:P and leaf C:N with soil N:P (P<0.05). The redundancy analysis revealed that soil C:P significantly affected the C, N, and P contents and stoichiometric characteristics of the leaves of plants in the Ebinur Lake Nature Reserve. (3) The changes in soil water and salt levels, the contents of N and P in the leaves, and the results of the endostatic model simulation of N:P were insignificant. The internal stability index H was > 4, which belonged to the absolute steady state, indicating that the plants in this study area demonstrated good adaptability to soil nutrients.

Desert plants have developed highly evolved water preservation and transportation systems for collecting and storing water through air under chronic water scarcity, the accessory structures such as trichomes on the leaf surface have important biological significance in collection, storage and transportation of the condensed water. Based on the current research progress, this review briefly summarizes the biological and ecological effects of condensate on desert plants, and expounds the theories related to leaf surface wettability and water collection capacity. Based on this, the important role of special structure of desert plants’ leaf surface (trichome) in the formation, transport and absorption of condensate is mainly discussed. The research methods of surface retention and absorption of condensate water were summarized, which may provide guidance for further study on trichome function and is helpful to understand the mechanism of condensate collection by desert plants driven by its structural characteristics in arid areas of China.

Mountain grassland are an essential component of pasture resources in the Xinjiang Uygur Autonomous Region. However, mountain grassland are highly vulnerable to human-associated disturbance and climate change. The responses of the mountain grassland plant community characteristics and diversity to different grazing managements in Barkol County, Xinjiang, are still unclear. In this study, three different grazing management treatments were set up in 2012 to investigate the response patterns of the plant community characteristics, diversity, and the relationship between the diversity and the aboveground biomass in the mountain grasslands. The three grazing management blocks were M0, M1, and M2, which represented the permanent grazing prohibition, winter grazing, and year-round grazing management, respectively. During the peak growing seasons of 2013, 2017, and 2022, the data regarding the number of species, height, coverage, density, and aboveground plant biomass were collected for further analysis. The results indicated that the different grazing managements had no significant impacts on the importance value of the dominant species, such as Stipa glareosa. However, the importance values of the nondominant species such as Neotrinia splendens and Achnatherum inebrians (Hance) Keng increased under winter and year-round grazing. As grazing intensity increased, plant height, coverage, density, aboveground biomass, and their response ratios declined significantly (P<0.05). There were no significant differences in the Shannon-Wiener diversity, Simpson dominance, and Pielou evenness indices in M0, M1, and M2. In contrast, the Margalef richness index elevated markedly (P<0.05), indicating that grazing provided more survival resources helpful for other species. In the permanent grazing prohibition block, the aboveground biomass was negatively correlated with the Simpson dominance, Shannon-Wiener diversity, and Pielou evenness indices. In the winter grazing block, aboveground biomass was negatively correlated with the Margalef richness index. Overall, the importance value of the dominant species showed no remarkable differences under varying grazing management, and its dominance remained unchanged. Except for the Margalef richness index, the other diversity indices were not significantly influenced by grazing. Winter and year-round grazing enhanced the vital value of unpalatable species, altering the composition of forage, which was not conducive to future animal husbandry development. In summary, as the enclosure time increased, permanent grazing prohibition was beneficial for restoring degraded grasslands, improving community characteristic values, improving grassland productivity, and maintaining community stability to a certain extent. Grazing would affect resource redistribution in the ecosystem, releasing ecological niches for more species, but year-round grazing led to intensified grassland degradation because of overgrazing pressure.

Through eco-measurement and research at the Xishawo desert pasture in Minqin for 60 a, it was found that desert vegetation flora has experienced four main stages with ground water-table decline, they were the degraded meadow steppe and Tamarix flora, Tamarix and Nitraria flora, Nitraria and degraded Tamarix flora, and Nitraria flora, the plant diversity and coverage dcreased in the processing, eco-degradation and desertification developed remarkably; with rain-fed area enlargement, desert herbal plants grew when precipitation was higher in the year, the plant diversity and coverage increased, and vice versa; some desert shrubs were relatively stable, its population growth and development improved when precipitation was over 140 mm, 100-140 mm for basic growth, and < 100 mm degraded gradually; most plant species of windbreak and sand-fixation afforestation degraded under drought conditions, Haloxylon ammodendron had strong eco-adaptability as an introduced species, it has developed into the biggest man-made windbreak and sand-fixation forest in Minqin desert areas, its big density and drought land were the main reasons for degradation, and sustainability could be increased under low density afforestation according to local plant carry capacity. Recently, with the integrated program implementation in the Shiyang River watershed area, eco-water has been increased, groundwater table has increased in some surroundings, some micro-wetlands have formed, original desert meadow steppe has reoccured, and their ecosystems are developing positively; however, ground water table still reduces slowly in most desert areas, and desertification has developed.

Vegetation carbon use efficiency (CUE) can objectively reflect the efficiency of vegetation in sequestering atmospheric carbon and the response of vegetation to climate change. Using MOD17, land use, and meteorological data, this study applied methods, such as the Hurst exponent, correlation analysis, and sensitivity analysis to explore the spatiotemporal variability of vegetation CUE and its sensitivity to climate factors in the Shaanxi section of the Yellow River Basin from 2001 to 2021. The results showed that (1) From 2001 to 2021, the gross primary productivity, net primary productivity (NPP), and vegetation CUE in the Shaanxi section of the Yellow River Basin exhibited an increasing trend, with an average CUE value of 0.51. (2) The study area was only 14.21% of the region, exhibiting a decreasing trend. The high-value areas of vegetation CUE are primarily concentrated in the windbreak and sand-fixation areas and the Grain for Green Project areas of northern Shaanxi. The areas where vegetation CUE indicated a decreasing trend accounted for 59.96%, most of which transitioned from an increasing trend to a decreasing trend. (3) Overall, temperature and precipitation correlated negatively with vegetation CUE, but the relationship with precipitation is more significant. Regions with positive correlations with temperature and precipitation are distributed in northern Shaanxi’s windbreak and sand-fixation areas. Sensitivity analysis of temperature and precipitation showed that the threshold values were 10 °C and 500 mm, respectively. When the temperature is below 10 °C and the precipitation is below 500 mm, the vegetation CUE increases with increasing temperature and precipitation. The relationship between vegetation CUE and climate factors is more significant and sensitive in arid areas, such as the conversion of farmland to forests and windbreak and sand-fixation areas in northern Shaanxi.

The study of vegetation dynamics and its influencing factors can reveal the response mechanism between vegetation cover dynamics and climate change and has important significance for regional vegetation restoration and ecological sustainability. Based on MODIS multitemporal remote sensing satellite data, this study investigated the quarterly changes in vegetation cover in the arid and semi-arid regions of Northwest China from 2000-2020 using variation coefficient, Theil-Sen median trend analysis, Mann-Kendall significance test, correlation analysis, and Hurst index. The study found that: (1) The spatial variability of the Normalized Difference Vegetation Index (NDVI) was high in winters, and the high fluctuation areas were mainly in the grasslands and unused land areas in the Daxinganling region of Xinjiang and Inner Mongolia. (2) NDVI fluctuates more with the seasons and is most obvious in forests and cultivated areas. (3) NDVI is mainly improving, with the largest improvement in springs (84.63%), the smallest in winters (72.52%), and the most significant improvement in the woodland areas. (4) Surface temperature and precipitation influenced NDVI in all seasons (Significance = 0.05), with precipitation changes significantly affecting NDVI trends in summers and weakly during winters and surface temperature changes significantly affecting NDVI trends in springs and weakly in autumns. (5) The future NDVI also mainly shows an improving trend, with an area of 70.89%; notably, the degraded areas are sporadically distributed in the Tarim and Junggar Basins of Xinjiang. This study’s results provide theoretical references for ecological restoration and management in the arid and semi-arid regions of Northwest China and the response to local climate warming and humidification.

As a highly serious soil and water loss area in the Loess Plateau, vegetation growth plays an important role in controlling soil erosion and maintaining ecological balance. This study calculated the net primary productivity of vegetation NPP and 18 extreme climate indices in the Pisha sandstone area from 2001 to 2021 based on the CASA model and Rclimdex 1.0, respectively. Trend analysis, correlation analysis, random forest importance ranking, and residual analysis were used to study the spatial-temporal variation of NPP and its response to climate factors in the Pisha sandstone area. The relative contributions of climate factors and human activities to the NPP in the Pisha sandstone area were also calculated. The results showed that (1) NPP variation in all regions of the Pisha sandstone area from 2001 to 2021 had a significant increasing trend, but in the future, 82.5% of the NPP in the Pisha sandstone area will change to a decreasing trend. (2) On the annual scale, NPP correlated positively with average annual temperature, total annual precipitation, and extreme heavy precipitation index and correlated negatively with cold night days TN10P and diurnal temperature range DTR. On the seasonal scale, the increase in average temperature and warm night days in spring was conducive to increase NPP, and there is a lag effect. Increasing the number of warm days in summer was unconducive to vegetation growth, and the NPP has a three-month lag response to the number of warm days in summer. Extreme heavy precipitation in summer was conducive to NPP increase, whereas summer drought was unconducive to vegetation growth, and NPP has a three-month lag response to the number of continuous dry days. (3) Both climate change and human activities contribute positively to NPP in the Pisha sandstone area. The climate contribution of the bare area and the covered sand area is dominant (62.13% and 60.06%, respectively), whereas that of the covered soil area is dominated by human activities (60.40%).

Xylem structure traits are the basis for plant adaptation to different water conditions and are core plant traits in response to changes in environmental conditions. The typical shrubs Reaumuria soongarica and Calligonum mongolicum in the northwest desert region were selected as the subjects for comparison between stem xylem structure and functional traits to understand the differences or similarities of different species in the same habitat and the xylem structure plasticity of the same species under different environmental conditions. The results showed that (1) Xylem structure traits of R. soongarica and C. mongolicum were significantly different. The mean vessel diameter and vulnerability index of C. mongolicum were significantly higher than those of R. soongarica, whereas the opposite was true for vessel density and vessel grouping index. (2) The patterns of xylem structure traits in response to climate change differed between R. soongarica and C. mongolicum. The mean vessel diameter and vessel thickness-to-span ratio of C. mongolicum significantly reduced with increasing mean annual precipitation and aridity index, whereas that of R. soongarica were unrelated, and only the theoretical hydraulic conductivity had a significant positive correlation with the mean annual precipitation and aridity index. (3) There was a trade-off between efficiency and safety in the xylem hydraulic conductivity system of R. soongarica, whereas none was observed in C. mongolicum. (4) The trait network analysis results indicated that the central traits of both R. soongarica and C. mongolicum were mean vessel diameters. Changes in mean vessel diameter mediate changes in the trait network. Xylem structure traits between R. soongarica and C. mongolicum were significantly different, with R. soongarica having a more conservative water use strategy than C. mongolicum.

To construct shelter forests in arid areas, selecting plant species with strong stress tolerance and adaptability is key. By simulating a pot water control experiment with different drought gradients, the ecological adaptability of the introduced plant Atriplex canescens and the native plant Tamarix ramosissima willow to drought stress were compared. The results showed that (1) With an increase in drought degree, the water content in the A. canescens and T. ramosissima leaves reduced gradually, and the water retention capacity, proline content, and relative conductivity gradually increased. The soluble sugar and malondialdehyde contents of A. canescens and T. ramosissima were the maximum in mild and severe drought, respectively, and the increase rate was greater in T. ramosissima. (2) The POD activity of A. canescens and T. ramosissima increased gradually, and under severe drought, the percentage increase of T. ramosissima compared with the control was approximatelythree times that of A. canescens; SOD activity was greatest under moderate drought, and the percentage increase in T. ramosissima compared with the control was approximatelyfive times that of A. canescens. The changes in the activity of both enzymes of T. ramosissima were greater than those of A. canescens. (3) The chlorophyll content of A. canescens and T. ramosissima were mildly dry > control > moderate drought > severe drought, the net photosynthetic rate, transpiration rate, stomatal conductance, and intercellular carbon dioxide concentration of T. ramosissima gradually decreased, and mild drought slightly promoted chlorophyll and photosynthetic capacity of A. canescens. (4) The correlation and principal component analysis results indicated that the relationship between the T. ramosissima traits was closer under drought stress, and the relationship between traits and traits was difficult to change in A. canescens, which was relatively conservative. Conclusion: A. canescens is less affected by drought stress, and its drought adaptability is slightly stronger than that of T. ramosissima.

To reveal the survival strategy of plants in semi-arid coal mining subsidence areas faced with soil erosion stress, 2-3-year-old Artemisia ordosica plants were used as the test materials and in-situ root structure destruction tests were carried out at four levels: severe stress (P1), moderate stress (P2), mild stress (P3), and control (CK). The changes in growth indices, photosynthetic characteristics, and physiological traits of A. ordosica were measured. The results showed that soil erosion stress significantly inhibited the growth rate of A. ordosica, and that the greater the degree of simulated damage, the more significant the growth inhibition. After severe stress, the growth rates of plant height, crown width, branch length, and branch diameter of A. ordosica decreased by an average of 36.91%, 43.90%, 69.76%, and 66.76 %, respectively, compared to control plants. Soil erosion stress also conferred a significant negative effect on the photosynthesis of A. ordosica, and the greater the degree of damage, the stronger the negative effect. After severe stress, the net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration, transpiration rate, and chlorophyll content of A. ordosica decreased by 39.86%, 59.26%, 7.82%, 51.55%, and 12.33%, respectively, compared to control plants. After 70 days of erosion stress, the activities of superoside dismutase (SOD), peroxidase (POD), and oxidoreductase (CAT) in A. ordosica initially increased and later decreased, and tended to be stable when compared with the control. The malondialdehyde (MDA) content fluctuated within a certain range. Redundancy analysis showed that the level of SOD activity had the most significant effect on the photosynthetic characteristics of A. ordosica. Comprehensive analysis showed that the root fracture of A. ordosica caused by soil erosion in coal mining subsidence areas will reduce its growth rate and inhibit photosynthesis. However, A. ordosica can maintain its growth by regulating the activity of its antioxidase systems and can therefore be considered to be an ecological restoration plant species due to its excellent resistance and adaptability in erosive areas.

Understanding the species diversity of submerged plant communities in response to nitrogen and phosphorus nutrition levels in sediments can clarify the relationship between the two. This relationship has direct theoretical and practical significance for studying the spatial and temporal changes of wetland vegetation and environment, and has implications for habitat restoration, pollution control, and planning management in the study area and similar areas. In this study, the wetland areas (lakes and ditches) of Yinchuan Plain were used as the research area to conduct a field survey of the submerged plant communities to obtain an understanding of the environmental sediment nutrients. Three typical submerged plant communities were screened out by the community classification method, and the nitrogen and phosphorus nutrient levels of the wetland sediment were evaluated. A structural equation model was used to analyze the relationship between the species diversity of typical submerged plant communities and the nitrogen and phosphorus nutrient components of the sediments. The results revealed that eight common submerged plants exist in the wetlands of Yinchuan Plain. The typical submerged plant communities were identified as a Potamogeton pectinatus community, a Myriophyllum spicatum community, and a Potamogeton crispus community. The species composition diversity and species contribution of the Potamogeton crispus community were high, and the species distribution was uniform. The species in the Potamogeton pectinatus community showed cluster or patchy distribution. Three levels (rich, moderate, and poor) of nitrogen and phosphorus fertility were identified in the sediment of the wetlands of Yinchuan Plain, and moderate and poor levels of fertility were most commonly found. The Potamogeton pectinatus and Myriophyllum spicatum communities were found to grow mainly in the poor- and moderate-level fertility sediment areas, while the Potamogeton crispus community was found to grow in all three levels of sediment nutrient content. The nitrogen and phosphorus nutrition level of the sediment had a significant positive effect on the three typical submerged plant communities, promoting an increase in the community diversity index. The characteristics of the three typical submerged plant communities were mainly affected by species evenness. The nitrogen and phosphorus fertility level of the sediment was mainly affected by the phosphorus level in the sediment.

In recent years, with global warming, the increase of drought events has a more important impact on the photosynthesis of vegetation, and also seriously affects the balance of terrestrial ecosystems. Based on SPEI base v.2.7 and GOSIF GPP data set, this paper studies the cumulative and time-delay effects of drought on GPP in northern grassland. Sen’s slope test, MK trend test and Mann-Kendall mutation test were used to study the temporal and spatial changes of GPP and SPEI during the study period. Pearson correlation analysis method was used to explore the cumulative and time-delay effects of drought on GPP in the north grasslands. The results showed that: (1) From 2001 to 2020, the annual average GPP of the northern grasslands showed a spatial distribution pattern of high in the northeast and low in the southwest, and the annual average SPEI showed a spatial distribution pattern of low in the northeast and high in the southwest, and the annual average of SPEI and GPP showed an upward trend over time. (2) Drought has a cumulative effect on 84.99% of the northern grassland, and the longest cumulative time scale is mainly concentrated in 3-4 months, covering 39.82% of the northern grassland; Drought had a lagging effect on 63.11% of the northern grassland, and mainly occurred in 7 months, covering 19.73% of the northern grasslands. (3) By comparing the variation trends of drought and drought under different water conditions, we found that the cumulative effect of drought on grassland GPP was stronger than the time-lag effect.

The influence of different slope-facing environmental factors on the natural regeneration of Picea schrenkiana in the middle section of the northern slope of Tianshan Mountains was investigated. A series of plots were established on shady, semishady, semisunny, and sunny slopes at the same altitude, in a Picea schrenkiana forest to develop the structure equation model for the regeneration index which uses different slope-facing environmental factors. According to the environmental characteristics of the different slope-facings, the relationship between the survival status of Picea schrenkiana seedlings and environmental factors was analyzed. The results showed that the semishady and semisunny slopes were more suitable for the survival and growth of seedlings, and the regeneration indexes of the two slopes (0.065 and 0.057) were significantly higher than those of the shady and sunny slopes. Litter was found to have a dual effect on the regeneration of Picea schrenkiana. The undecomposed litter layer was too thick to be beneficial to regeneration, while the rich organic matter could promote the formation of a high nitrogen environment in the soil, which was conducive to the regeneration of seedlings. The influence of different slope-facing environmental factors on the regeneration index was in the order of total nitrogen content (0.60) > adult tree density (0.46) > litter half-decomposed layer (0.37) > total potassium content (0.24) > organic matter content (0.23) > total phosphorus content (-0.16) > available phosphorus content (-0.32) > litter undecomposed layer thickness (-0.34). Overall, the regeneration of Picea schrenkiana seedlings in the region was best on the semishady and semisunny slopes with a closure degree of approximately 0.6 and litter thickness of approximately 2.5 cm, as well as high total nitrogen and total potassium contents in the soil.

Forest surface combustibles are one of the important factors in forest fire propagation, and their calorific values are an important index by which to assess combustibility. This study has aimed to assess the surface fuels available in four typical vegetation types in the eastern Tianshan Mountains of Xinjiang, China. The characteristics of the surface fuel calorific values and relationship with ignition point and absolute moisture content were analyzed. The results show that in coniferous and broad-leaved forests, there were significant differences between herb and litter components, while in shrub forest, there were significant differences between shrub and litter components. Within the same forest the calorific values were litter > herb > shrub > humus. The calorific values in the coniferous forests were the highest among the herbaceous fuel components (19.38 ± 0.08 kJ·g^-1), while those in the coniferous forests were highest among the litter fuel components (19.55 ± 0.05 kJ·g^-1). Differences were identified in the relationship between the calorific value and the ignition point of the surface combustibles for the different components. There was a significant correlation between the burning point of the shrub fuel components and the calorific value (R² = 0.81, P < 0.01), and between the burning point of litter fuel components and the calorific value (R² = 0.38, P < 0.05). However, there was no significant correlation between the burning point and calorific value of the herbs and humus (P > 0.05). In addition, there was no significant correlation between the calorific values of the surface fuel and the absolute moisture content of all forest types. Forest type, tree species, physical and chemical properties, and other conditions were thus found to have a comprehensive effect on the calorific values of the different fuels. The results of this study provide a theoretical basis for forest fire management in the eastern Tianshan Mountains as they will help to accurately predict the calorific energy and potential forest fire risks and provide data support for in-depth research on regional surface fuels.

The allocation pattern of plant biomass and its input into the soil are key processes for restoring degraded sandy grassland, especially regarding soil carbon accumulation. In this study, mobile dunes, semifixed dunes, fixed dunes, and fenced grasslands in Horqin Sandy Land at different restoration stages were investigated. By analyzing the biomass allocation of herbaceous vegetation, root traits, soil physicochemical properties, and their interrelations, it was found that the aboveground biomass, root biomass, surface litter, and underground necromass all increased significantly (P<0.05) with the extent of desertified grassland restoration. Compared to severely desertified mobile dunes, the total dry matter (biomass+litters) in semifixed dunes, fixed dunes, and fenced grasslands increased by 11.01%, 116.29%, and 151.18%, respectively. Similar to the changes in biomass, soil carbon content also increased significantly (P<0.05) with the extent of desertified grassland restoration, with a higher increase rate observed in the 0-10 cm layer than the 10-20 cm layer. Structural equation modeling indicated that the soil carbon content in the 0-10 cm layer was influenced by the surface litter mass, underground necromass, and root surface area. Conversely, soil carbon content in the 10-20 cm layer was affected only by underground necromass and root surface area. Moreover, the soil carbon content in both layers showed an insignificant relationship with aboveground biomass. In conclusion, the soil carbon content in degraded sandy grassland is primarily affected by litter input and root traits but has an insignificant relationship with aboveground biomass.

To reveal the physiological response of typical crops to saline-alkali stress, we selected Jerusalem artichoke (Helianthus tuberosus) as our research object. We set up three different treatments: a complete nutrient soil group (CK), a light saline-alkali soil group (LS), and a moderate saline-alkali soil group (MS). Changes in physiological indicators, such as organic osmoregulatory substances (soluble sugar, soluble protein, and proline); malondialdehyde (MDA) content; and activities of antioxidant enzyme systems [superoxide dismutase (SOD), peroxide dismutase (POD), and catalase (CAT)] of Helianthus tuberosus were investigated. The results showed the following: (1) The content of organic osmoregulatory substances in Jerusalem artichoke leaves, including soluble sugar, proline, and soluble protein, increased under different intensities of saline-alkali stress. (2) The groups had no significant differences in MDA content. However, with increased saline-alkali stress intensity, the activity indexes of antioxidant enzyme systems, such as SOD, POD, and CAT, in Jerusalem artichoke leaves showed an upward trend. After 150 days of saline-alkali stress, the SOD activity in the LS and MS groups increased significantly by 22.13% and 26.49%, respectively, compared to the CK group. Additionally, CAT activity in the LS and MS groups increased significantly by 81.66% and 92.38%, respectively, compared to the CK group (P < 0.05). Moreover, POD activity in the MS group was significantly higher than in the CK group during the same period. The above findings demonstrate that Helianthus tuberosus can adapt to a saline-alkali environment by increasing the content of osmoregulatory substances (soluble sugar, soluble protein, and proline) and activating the antioxidant enzyme system (SOD, CAT, and POD), indicating its strong tolerance to saline-alkali stress.

As the largest carbon reservoir on land, forests play a crucial role in human life and development. Understanding the dynamic changes in forest resources and modernizing their sustainable development is currently a significant research focus. This study focuses on natural Picea forests in the Tianshan Mountains and uses ground measurement data, helicopter airborne LiDAR point cloud data, and Global Ecosystem Dynamics Investigation (GEDI) data to construct a multisource fusion data framework. By utilizing deep learning algorithms within the AutoKeras framework, the study aims to predict the regression model of multiple relative height quantiles of GEDI data and their aboveground biomass in the study area, thereby validating the feasibility of GEDI data for large-scale aboveground biomass retrieval. The main conclusions are as follows: (1) GEDI data are highly feasible for estimating forest aboveground biomass. Through automated deep learning algorithms and training and verification sets, the overall data achieve a coefficient of determination (R²) of 0.69, 0.63, and 0.67, respectively, along with a mean absolute error of 3.73 mg·hm^-2, 4.22 mg·hm^-2, and 3.89 mg·hm^-2, demonstrating high prediction accuracy. (2) Helicopter LiDAR, an intermediate technology for estimating aboveground biomass using GEDI data, exhibits a single tree recognition accuracy of over 0.75 across the study area. The study successfully utilizes multimodal data fusion to quantitatively describe the structural parameters of the single tree foundation in the study area while verifying the potential of GEDI data for obtaining forest aboveground biomass. Moreover, the study provides a theoretical basis for estimating carbon sources and sinks, biomass, stock, forest management, biodiversity protection, and other projects in similar areas, offering essential guidance, and fundamental data support.

We found four new records of Amaranthus exotic weeds in Altay, Ili, Changji, Tacheng, and Hami during a field survey of weeds in northern and eastern Xinjiang. We recorded three species and one variety, respectively, of Amaranthus hybridus L., Amaranthus powelli S. Watson, Amaranthus viridis L., and Amaranthus retroflexus L. var. delilei (Richter & Loret) Thell that have not yet been found in this region. There are small populations of A. hybridus L. in Xinyuan, Yili, Urumqi, and Hami. A. viridis L. is only found in multiple populations in the Wusu Chepaizi reclamation area. A. retroflexus L. var. delilei (Richter & Loret) Thell. is only distributed in a small portion of Shihezi City. A. powellii S. Watson is only found in Balikun County, Hami City. The discovery of these newly recorded plants is of great significance to the study of the flora and species diversity of Amaranthus in Xinjiang, and also provides an important basis and new data for the study of their geographical distribution and of the spread and effective detection of invasive weeds. Specimens from the recorded species are kept in the Herbarium of Shihezi University.

Based on the investigation and identification of bryophytes collected from Zhaosu County, West Tianshan Mountain, Xinjiang, one genus and two species of Leskeaceae new to Xinjiang are reported. They are Orthoamblystegium Dixon & Sakurai, Orthoamblystegium spurio-subtile (Broth. & Paris) Kanda & Nog. and Leskea scabrinervis Broth. & Paris. In this paper, the morphological characteristics, habitat and distribution were recorded for these two species. The microscopic structure photos of these two species were also provided.