Plant community stability and diversity play crucial roles in maintaining the stable performance of grassland ecosystem functions. In this study, we selected 55 representative grassland community sample plots in the Habahe Forest region of the Altai Mountains, Xinjiang. We examined the number of species, the number of individuals, and the cover of each species in the sample plots. Additionally, we determined the aboveground biomass of grassland communities, the stability of M. Godron communities, and plant diversity (using the Margalef index, Simpson index, Shannon–Wiener index, and Alatalo evenness index) in the sample plots. We analyzed community stability, plant diversity, and the correlation between community stability, plant diversity, and environmental factors (such as longitude, latitude, altitude, slope, humus thickness, soil thickness, air temperature, precipitation, and soil moisture). The results show that the plant coverage and height of different grassland types in the Habahe Forest area decrease from mountain meadow to desert steppe. The aboveground biomass and species diversity of meadows are significantly higher than those of steppes. The stability of different grassland types is as follows: montane steppe > montane meadow steppe > mountain meadow > desert steppe. The species richness of the four grassland types is positively correlated with community stability, while evenness is negatively correlated with community stability. Dominance in montane steppe and montane meadow steppe is significantly positively correlated with community stability, whereas diversity in desert steppe and montane steppe is significantly negatively correlated with community stability. Precipitation and soil moisture are the main factors affecting species diversity and stability in the Habahe Forest area. Soil nutrients and slope can also impact community stability by affecting species diversity. In summary, the ecological management of grasslands in the Habahe Forest area should consider climate, soil, and terrain factors, and different management measures should be selected to adapt to different grassland types.

Three different types of common halophytes (Haloxylon ammodendron, Tamarix chinensis, and Phragmites australis) in northwest China were used in this study. A field experiment approach was adopted, involving five solutions with different salt concentrations (0, 150, 200, 250, and 300 mmol·L⁻¹) for salt stress treatment. The changes in photosynthetic characteristics and physiological characteristics of three different types of halophytes and their relationship with biomass were measured and analyzed. The results showed that (1) with the increase in salt concentration, the plant height, stem diameter, and biomass of three halophytes showed a downward trend. (2) The chlorophyll a, chlorophyll b, and total chlorophyll contents of Haloxylon ammodendron and Tamarix chinensis first increased and then decreased with the increase in salt concentration. Phragmites australis showed a decreasing trend. The malondialdehyde content of three halophytes showed a clear increasing trend. (3) Under different salt concentrations, the diurnal changes in the net photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency of three different types of halophytes all showed an “M” trend. The diurnal variation in intercellular carbon dioxide concentration showed a “W” trend. (4) With the increase in salt concentration, the daily average values of the net photosynthetic rate, transpiration rate, and stomatal conductance of three different types of halophytes showed a downward trend. The daily average value of intercellular carbon dioxide concentration showed a “V”-shaped trend of first decreasing and then increasing. The daily average value of water use efficiency showed a “single peak” trend of first increasing and then decreasing. Haloxylon ammodendron and Phragmites australis were mainly limited by stomata at a salt concentration of 0~200 mmol·L⁻¹ and were mainly limited by non-stomata at a salt concentration of 250~300 mmol·L⁻¹. Tamarix chinensis is mainly limited by stomata at a salt concentration of 0~250 mmol·L⁻¹ and is mainly limited by non-stomata at a salt concentration of 300 mmol·L⁻¹. Compared with Haloxylon ammodendron and Phragmites australis, Tamarix chinensis has better water use efficiency, salt tolerance, and adaptability. (5) Meteorological factors, growth morphological factors, physiological factors, photosynthetic factors, and salt concentration have higher explanatory degrees, which have significant effects on the biomass of halophytes. Among them, salt concentration and growth morphological factors have direct core driving effects on the biomass of three different types of halophytes, while meteorological factors, photosynthetic factors, and physiological factors have different effects due to the differences in and complexity of halophytes. This study can provide a theoretical basis for further revealing the adaptation mechanism of different halophytes to salt stress.

Grazing affects plant community characteristics and the relationship between above-ground biomass and diversity, which has become a hot topic in grassland ecosystem research in recent years. The present study investigated grassland vegetation in the Two Rivers pastoral area based on 60 sampling points using sampling methods. The effects of grazing on the structural characteristics of plant communities were analysed using the α-diversity index, and the relationship between species diversity and the above-ground biomass of plant communities, as well as their changes, was explored. The results showed that grazing disturbance decreased the number of family species in the grassland plant communities and the similarity between communities; grazing activities significantly decreased the above-ground biomass of the grassland plant communities; the height and cover also showed a decreasing trend (p < 0.01), but the density of the grassland plant communities improved (p < 0.01). The Margalef index, the Shannon–Wiener index, and the Simpson index of the grassland plant communities all showed different degrees of decrease after grazing, while the Alatalo index showed an increase; biomass was positively correlated with the Margalef, Shannon–Wiener, and Alatalo indices and negatively correlated with the Simpson index (p < 0.01). Therefore, in the management and maintenance of grasslands, the impact of grazing on the structural characteristics of plant communities should be taken into account, and reasonable response policies should be implemented according to the actual local situation. This study provides a theoretical basis for grassland maintenance and management and the sustainable development of ecosystems in the pastoral areas of the two river sources of the Altay Mountains.

In order to explore the changes and interrelationships of grassland plant community species diversity and soil physicochemical properties with elevation gradient, this study takes the grassland in the Burzin forest area of Xinjiang as the research object and analyzes the responses of grassland species diversity, aboveground biomass, and soil physicochemical properties to the changes of elevation gradient within the altitude range of 1000~2200 m in this area. The results of the study show that: (1) The number of species and aboveground biomass reached the highest levels at elevation gradient III and showed a tendency of increasing and then decreasing with elevation. The Margalef and Shannon–Wiener indices were the largest at elevation III, while the Simpson and Alatalo indices were the largest at elevation I. (2) With the change of elevation, the available nitrogen (AN), available phosphorus (AP), soil electric conductivity (SEC), and soil pH showed a trend of increasing and then decreasing, while soil temperature decreased with elevation. Available potassium and soil water content reached their maximum values at elevation I and elevation IV, respectively. (3) The soil conductivity and diversity index were negatively correlated in elevation gradients I to III. In elevation gradient I~III, soil conductivity was positively correlated with the diversity index and aboveground biomass. Available nitrogen had a significant effect on plant diversity and biomass in elevation gradients IV to VI. (4) Aboveground biomass was significantly positively correlated with the Simpson’s index, while the relationship with the Shannon–Wiener index was less significant, and Margalef’s and Alatalo’s indices were not significant. Soil conductivity and pH significantly affected the Margalef and Simpson indices. Available nitrogen was closely related to the aboveground biomass and Margalef and Alatalo indices. Soil moisture content significantly affected Simpson’s index and the aboveground biomass. This study provides a solid theoretical foundation for the conservation and management of grassland plant community ecosystems along the elevation gradient, and has important reference value for study of the impact of environmental change on species diversity and biodiversity conservation.

The change grassland plant communities demonstrate with elevation has been one of the hot issues in ecological research, and there remain many unsolved problems. In order to further elucidate the rules of grassland plant community change with elevation, this study took the Burqin forest area as a research object, using field survey, redundancy analysis and grey correlation analysis to comprehensively assess the characteristics of change in grassland plant communities with elevation and the relationship of this evolution with environmental factors. The results showed that (1) the numbers of species, community biomass, community cover and community densities of grassland plant communities showed an “M” pattern with the increase in elevation. There were significant changes in the importance values and dominance of plants at different elevations; with increasing elevation, grassland plants became primarily dominated by cold-tolerant and well-adapted perennials. (2) The similarity coefficients of grassland plant communities at different elevations ranged from 0.06 to 0.62, i.e., from very dissimilar to moderately similar. (3) As the elevation increased, the Margalef species richness index, Shannon–Wiener diversity index, Simpson dominance index and Alatalo evenness index all showed an “M” pattern trend. (4) The degrees of correlation between temperature and precipitation and community biomass and species diversity were at a high level, and these were the most important environmental factors affecting the biomass and species diversity of grassland plant communities in the Burqin forest area. The results of this study can provide a theoretical basis for the rational utilization of grassland resources and for the sustainable development of grassland ecosystems in the Burqin forest area.

The stability, diversity, and biomass of grassland plant communities directly impact the functionality and resilience of ecosystems, making them a focal point for ecological research. This three-year study (2021–2023) in the Habahe pastoral area of Xinjiang, China, aimed to investigate the long-term effects of grazing on grassland vegetation structure, community stability, species diversity, and productivity. The results indicate the following. (1) The Habahe pastoral area hosts a relatively rich plant species diversity, with 40 species distributed across 17 families and 37 genera, predominantly comprising perennial and annual herbs. (2) Grazing significantly affected grassland structure and function, resulting in a 4.35% decrease in plant community stability, a 40.74% decrease in species richness, a 21.55% decrease in species dominance, a 5.08% decrease in species diversity, a 46.79% decrease in aboveground biomass, a 61.86% decrease in coverage, and a 72.12% decrease in height. (3) Grazing alters the relationship between species diversity and community stability, shifting it from a positive correlation to a negative one (p < 0.01) or rendering it non-significant after grazing. (4) Grazing affects the correlation between aboveground biomass and both species diversity and community stability. While the positive correlation between aboveground biomass and species diversity persists, it is not statistically significant (p > 0.05) after grazing. Conversely, the correlation between aboveground biomass and community stability shifts from positive to negative (p < 0.01). These results emphasize the need for integrated management strategies that consider both grazing intensity and plant community composition to maintain the health of grassland ecosystems.