Alpine meadow and alpine steppe are the two most widely distributed nonzonal vegetation types in the Qinghai-Tibet Plateau. In the context of global climate change, the differences in spatial-temporal variation trends and their responses to climate change are discussed. It is of great significance to reveal the response of the Qinghai-Tibet Plateau to global climate change and the construction of ecological security barriers. This study takes alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau as the research objects. The normalized difference vegetation index (NDVI) data and meteorological data were used as the data sources between 2000 and 2018. By using the mean value method, threshold method, trend analysis method and correlation analysis method, the spatial and temporal variation trends in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau were compared and analyzed, and their differences in the responses to climate change were discussed. The results showed the following: (1) The growing season length of alpine meadow was 145~289 d, while that of alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau was 161~273 d, and their growing season lengths were significantly shorter than that of alpine meadow. (2) The annual variation trends of the growing season NDVI for the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau increased obviously, but their fluctuation range and change rate were significantly different. (3) The overall vegetation improvement in the Qinghai-Tibet Plateau was primarily dominated by alpine steppe and alpine meadow, while the degradation was primarily dominated by alpine meadow. (4) The responses between the growing season NDVI and climatic factors in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau had great spatial heterogeneity in the Qinghai-Tibet Plateau. These findings provide evidence towards understanding the characteristics of the different vegetation types in the Qinghai-Tibet Plateau and their spatial differences in response to climate change.

Understanding the primary mechanisms for plant promotion under salt stress with plant growth promoting rhizobacteria (PGPR) inoculation of different salt-tolerant plant groups would be conducive to using PGPR efficiently. We conducted a meta-analysis to evaluate plant growth promotion and uncover its underlying mechanisms in salt-sensitive plants (SSP) and salt-tolerant plants (STP) with PGPR inoculation under salt stress. PGPR inoculation decreased proline, sodium ion (Na⁺) and malondialdehyde but increased plant biomass, nutrient acquisition (nitrogen, phosphorus, potassium ion (K⁺), calcium ion (Ca²⁺), and magnesium ion (Mg²⁺)), ion homeostasis (K⁺/Na⁺ ratio, Ca²⁺/Na⁺ ratio, and Mg²⁺/Na⁺ ratio), osmolytes accumulation (soluble sugar and soluble protein), antioxidants (superoxide dismutase), and photosynthesis (chlorophyll, carotenoid, and photosynthetic rate) in both SSP and STP. The effect size of total biomass positively correlated with the effect sizes of nutrient acquisition and the homeostasis of K⁺/Na⁺, and negatively correlated with the effect size of malondialdehyde in both SSP and STP. The effect size of total biomass also positively correlated with the effect sizes of carotenoid and the homeostasis in Ca²⁺/Na⁺ and Mg²⁺/Na⁺ and negatively correlated with the effect size of Na⁺ in SSP, but it only negatively correlated with the effect size of Ca²⁺ in STP. Our results suggest that the plant growth improvement depends on the nutrient acquisition enhancement in both SSP and STP, while ion homeostasis plays an important role and carotenoid may promote plant growth through protecting photosynthesis, reducing oxidative damage and promoting nutrient acquisition only in SSP after PGPR inoculation under salt stress.

Desertification is a global eco-environmental hazard exacerbated by environmental and anthropogenic factors. However, comprehensive quantification of each driving factor’s relative impact poses significant challenges and remains poorly understood. The present research applied a GIS-based and geographic detector model to quantitatively analyze interactive effects between environmental and anthropogenic factors on desertification in the Shiyang River Basin. A MODIS-based aridity index was used as a dependent variable, while elevation, near-surface air temperature, precipitation, wind velocity, land cover change, soil salinity, road buffers, waterway buffers, and soil types were independent variables for the GeoDetector model. A trend analysis revealed increased aridity in the central parts of the middle reach and most parts of the Minqin oasis and a significant decrease in some regions where ecological rehabilitation projects are underway. The GeoDetector model yielded a power determinant (q) ranging from 0.004 to 0.270, revealing elevation and soil types as the region’s highest contributing factors to desertification. Precipitation, soil salinity, waterway buffer, and wind velocity contributed moderately, while near-surface air temperature, road buffer, and land cover dynamics exhibited a lower impact. In addition, the interaction between driving factors often resulted in mutual or non-linear enhancements, thus aggravating desertification impacts. The prominent linear and mutual enhancement occurred between elevation and soil salinity and between elevation and precipitation. On the other hand, the results exhibited a non-linear enhancement among diverse variables, namely, near-surface air temperature and elevation, soil types and precipitation, and land cover dynamics and soil types, as well as between wind velocity and land cover dynamics. These findings suggest that environmental factors are the primary drivers of desertification and highlight the region’s need for sustainable policy interventions.

Halophytes could withstand the hyper-salinity soil and survive widely in areas where soil salt content is high because they can endure salt stress to a certain extent. Lycium ruthenicum Murr (LRM), with significant nutritional and medicinal values, is one of the most important native halophytes in the arid oasis-desert transition zone of northwestern China. In recent years, artificially planting LRM has been being popular since it can improve saline-alkalized soil and increase the income of local farmers as well. More efforts about the artificial planting of LRM are put in enhancing the productivity and quality, but survivorship of LRM seedling by appropriate saline irrigation is still unclear in arid areas. A field experiment was conducted to explore the responses of LRM to four levels of saline water irrigation (Ec of irrigation water: 2.00 μs cm⁻¹ (T₁), 4.51 μs cm⁻¹ (T₂), 6.89 μs cm⁻¹ (T₃), and 9.00 μs cm⁻¹ (T₄)) during the growing seasons in 2014 and 2015. The average soil electrical conductivity (Ec_a) in 0–60 cm depth increased while the biomass of LRM decreased with increasing Ec of irrigation water, and the differences of Ec_a among treatments decreased with increasing salinity level. In contrast to previous research findings, salt stress had more significant effect on photosynthesis and chlorophyll fluorescence of LRM, in which great changes were caused by a threshold following the increased salinity. Most of the light energy absorbed by LRM was used for photosynthesis and heat dissipation when soil salinity was low, what was used for chlorophyll fluorescence when soil salinity was high. The results of the experiment indicate that T₂ was the most suitable irrigation method for artificially planting LRM in the field, and it’s the key to save freshwater resources in arid areas and improve the production of saline-alkali land.