The plant-specific SHI-related sequence (SRS) family of transcription factors plays a vital role in growth regulation, plant development, phytohormone biosynthesis, and stress response. However, the genome-wide identification and role in the abiotic stress-related functions of the SRS gene family were not reported in white sweet clover (Melilotus albus). In this study, nine M. albus SRS genes (named MaSRS01-MaSRS09) were identified via a genome-wide search method. All nine genes were located on six out of eight chromosomes in the genome of M. albus and duplication analysis indicated eight segmentally duplicated genes in the MaSRS family. These MaSRS genes were classified into six groups based on their phylogenetic relationships. The gene structure and motif composition results indicated that MaSRS members in the same group contained analogous intron/exon and motif organizations. Further, promoter region analysis of MaSRS genes uncovered various growth, development, and stress-responsive cis-acting elements. Protein interaction networks showed that each gene has both functions of interacting with other genes and members within the family. Moreover, real-time quantitative PCR was also performed to verify the expression patterns of nine MaSRS genes in the leaves of M. albus. The results showed that nine MaSRSs were up- and down-regulated at different time points after various stress treatments, such as salinity, low-temperature, salicylic acid (SA), and methyl jasmonate (MeJA). This is the first systematic study of the M. albus SRS gene family, and it can serve as a strong foundation for further elucidation of the stress response and physiological improvement of the growth functions in M. albus.

In recent years, ecological concerns such as vegetation destruction, permafrost deterioration, and river drying have been paid much more attention to on the Yellow River Basin in China. Soil pH is regarded to be the fundamental variable among soil properties for vegetation growth, while net primary productivity (NPP) is also an essential indicator to reflect the healthy growth of vegetation. Due to the limitation of on-site samples, the spatial–temporal variations in soil pH and NPP, as well as their intrinsic mechanisms, remain unknown, especially in the Yellow River source area, China. Therefore, it is imperative to investigate the coupling relationship between soil pH and NPP of the area. The study coupled MODIS reflectance data (MOD09A1) with on-site soil pH to estimate spatial–temporal variations in soil pH, explore the response of NPP to soil pH, and assess the extent to which they contribute to grassland ecosystems, thus helping to fill knowledge gaps. Results indicated that the surface spectral reflectance for seven bands could express the geographic pattern of soil pH by applying a multiple linear regression equation; NPP exhibited an increasing trend while soil pH was the contrary in summer from 2000 to 2021. In summer, NPP was negatively correlated with soil pH and there was a lag effect in the response of NPP to soil pH, revealing a correlation between temperate steppes > montane meadows > alpine meadows > swamps in different grassland ecosystems. In addition, contribution indices for temperate steppes and montane meadows were positive whereas they were negative for swamps and alpine meadows, which are apparent findings. The contribution index of montane and alpine meadows was greater than that of temperate steppes and swamps. The approach of the study can enable managers to easily identify and rehabilitate alkaline soil and provides an important reference and practical value for ecological restoration and sustainable development of grassland ecosystems in alpine regions.

The Gannan Water Conservation area is an indispensable part of the ecological barrier on the Tibetan Plateau and is a key ecological area for the water supply. Exploring the coupled coordination relationship between vegetation and soil contributes to the conservation and planning of the natural environment. In this study, soil water conservation function (SWCF) was investigated with Moderate Resolution Imaging Spectroradiometer (MODIS) data in the Gannan Water Conservation Area at the source of the Yellow River, and the spatiotemporal coupling relationship between the SWCF and vegetation was explored. Meanwhile, their responses to topographic and climatic factors were investigated with structural equation models. The main results indicated that the coupling coordination degree (D_VS) in the soil depth was in a barely coordinated state, with 0–10 cm > 20–30 cm > 10–20 cm, showing that the area proportion of ‘Basic balanced–Synchronous development of VEG and SWCF’ was the highest, and the spatial aggregation feature was obvious. As the gradient of topographic factors varied, the coupling coordination also varied at various soil depths. Meanwhile, the absolute values of the correlation coefficients of the temperature and precipitation with the coupling coordination were the highest at 20–30 cm compared to the other soil depths, demonstrating that the effect was more significant in deeper soils than in shallower ones. Furthermore, the path coefficients of the topographic factors were larger than those of the climatic factors in the 10–20 cm and 20–30 cm layers, while the opposite was true in the 0–10 cm layer. In general, the vegetation conditions and water conservation function of soil in the source area of the Yellow River are basically developing synchronously, and the topographic factor is the key factor for the geographical difference in the coupling relationship between the two factors.

In recent decades, with the acceleration of industrialization and urbanization, the contradiction between resource development and environmental protection has become more and more prominent. Scientific simulation of the spatial and temporal correlation between habitat quality (HQ) and habitat fragmentation at a suitable scale is of great significance for maintaining the stability of regional ecosystems and achieving high-quality development. This study took the West Qinling Mountains as an example, where, firstly, the appropriate grid scale was determined based on the spatial stability of HQ, and the evolution characteristics of HQ were analyzed from 2000 to 2020 based on the InVEST model and GeoDa software. Secondly, the habitat fragmentation process was simulated from three characteristic dimensions of habitat area, habitat shape, and habitat distribution. Finally, the GWR model was used to explore the correlation mechanism between habitat fragmentation and HQ. The results showed the following: (1) The 3 km grid scale was a suitable scale for HQ evaluation and analysis in the West Qinling Mountains, and the scale effect was consistent across years. (2) The degree of HQ was at a higher level, where, from 2000 to 2020, it showed a decreasing trend, with a clear phenomenon of bipolar sharpening. The spatial distribution showed a pattern of “high in the west and low in the east, low in the north and high in the south”, and exhibited obvious spatial double clustering characteristics. (3) The degree of habitat fragmentation was at a medium level, where, from 2000 to 2020, it showed a increasing trend, with a clear bipolar contraction state. The spatial distribution showed a pattern of “high in the east and low in the west, high in the north and low in the south”, and the overall spatial distribution was retained with the change in time scale. (4) The effects of habitat fragmentation on HQ showed significant spatial and temporal non-stationary with a non-linear negative correlation. From 2000 to 2020, the degree of negative effect gradually increased, and the staggered distribution of forest, unused land, and water might offset the negative impact of unused land on HQ. The results could provide scientific evidence for the optimization of ecological patterns and ecological prevention and control in the West Qinling Mountains.

Soil water–salt variations at different spatiotemporal scales and their influencing factors are essential for regional vegetation restoration and management. However, the study of soil water–salt of the alpine area has not taken into account the effect of topography, especially in the long time series. This work investigated the spatiotemporal characteristics of water and salt in topsoil from 2000 to 2021, using regression analysis of on-site data and MODIS products. The heterogeneity and trends of soil water–salt in various topographic factors (elevation, slope, and aspect) were also explored by selecting the maximum area of each gradient factor as the constrained condition with the help of ArcGIS software. The results revealed that 1) the models applied to SWC (soil water content), EC (electrical conductivity), and pH utilizing vegetation indices were suitable for estimating the spatiotemporal variations of soil water–salt. 2) Soil water–salt exhibited local aggregation characteristics with an upward trend in SWC and a downward trend in EC and pH as a whole. 3) Mean annual SWC peaked at 3,400–3,800 m with increasing elevation and trended downward with increasing slope. The aspect of mean annual SWC was characterized by lower values in the southwest and south and higher values in the north, while the results for pH were reversed. The slope had a greater influence on EC than on SWC and pH. 4) The trend change of SWC, EC, and pH fluctuated at 2000–2,400 m and >4,600 m with a clear inflection point at 4°–8° and 20°–24°, respectively. In summary, the effects of topography responded to the distribution and trends of soil water–salt. The results have significant implications for implementing ecological improvements in regions with complicated topography and can serve as a reference for formulating future ecological policies.

Lanzhou is the only provincial capital city in Northwest China where the main stream of the Yellow River and its tributaries flow through the city. Due to its geographical location and the influence of various factors, it is difficult to evaluate and simulate the climatic, hydrological, and ecological processes of the main stream of the Yellow River and its tributaries in the region. In this study, the Wanchuan River basin, currently undergoing ecological restoration, was selected as the study area. Seasonal backscatter differences generated using Sentinel-1/2 (S1/S2) data and the CD algorithm were used to reduce the effects of surface roughness; vegetation indices, soils, and field measurements were used to jointly characterize the vegetation contribution and soil contribution. Then, SM maps with a grid spacing of 10 m × 10 m were generated in the Wanchuan River basin, covering an area of 1767.78 km². To validate the results, optimal factors were selected, and a training set and validation set were constructed. The results indicated a high level of the coefficient of determination (R²) of 0.78 and the root mean square error (RMSE) of 0.08 for the comparison of measured and inverted water contents, indicating that the algorithm retrieved the SM values of the study area well. Furthermore, Box line plots with ERA5-Land and GLDAS confirmed that the algorithm is in good agreement with current SM products and feasibility for soil water content inversion work in the Wanchuan River basin.