A new species, Astragalus liuaiminii Z. Z. Yang & Q. R. Liu (Fabaceae), is described and illustrated from Xinjiang Province, China. The new species is close to A. wenquanensis S. B. Ho, but differs from the latter by leaves having a single leaflet (vs. 3–5 leaflets), and inflorescences with 1–2 flowers (vs. inflorescences with 5–7 flowers). It is also similar to A. monophyllus Maxim in leaf shape, but differs by its calyx expanding to become saccate and totally enveloping the pod (vs. calyx tubular, and ruptured by pod after flowering).

In order to study the effects of litter decomposition on soil nitrogen of Piceamongolica in different forest ages, young forest (0–5a), middle-aged forest (5–30a), and near-mature forest (30–40a) stands were selected in the Baiyinaobao National Nature Reserve. Litter decomposition was assessed using the decomposition bag method. The seasonal and vertical spatial variation characteristics of total N, NH₄⁺—N, and NO₃⁻—N caused by litter decomposition in P. mongolica forest soil were studied for different stand ages. Results showed that: (1) There was a positive correlation between litter N content and soil organic matter, total N content, and NO₃⁻—N content across different forest ages (p < 0.05). There was a negative correlation between litter N and NH₄⁺—N contents. A negative correlation between litter C content and soil organic matter, total N, and NO₃⁻—N contents was also observed. (2) In this study, the total N and NO₃⁻—N increased with the increase in N content during litter decomposition.NH₄⁺—N in the soil was positively correlated with sample date, soil NO₃⁻—N, and forest age (p < 0.05), and negatively correlated with soil depth (p < 0.01). NO₃⁻—N in the soil was negatively correlated with sample date and forest age (p < 0.05), and significantly negatively correlated with soil depth (p < 0.01). (3) the NH₄⁺—N content is greater than that of NO₃⁻—N in each soil layer for the three forest ages. The correlation analysis indicated which factors influenced NH₄⁺—N and NO₃⁻—N in the soil. The content decreased during February and November and increased in May and August. (4) The total N, NH₄⁺—N, and NO₃⁻—N in the forest soils across the three forest ages increased with the depth of the soil layer (0–50 cm) and showed an overall downward trend. The contents of NH₄⁺—N in the soil layer from the young forest (0–10 cm, 10–20 cm and 20–30 cm, 30–40 cm, and 40–50 cm) differed significantly (p < 0.05), as did the NO₃⁻—N results (p < 0.05), while results from the middle-aged forest and near-mature forest increased with soil layer depth. There was no significant difference in the NH₄⁺—N soil content. (5) The NH₄⁺—N in the forest soils showed a trend from mature forest > middle-aged forest > young forest. This trend for soil NO₃⁻—N content is consistent with that of the NH₄⁺—N content in the Picea mongolica forest soil.

The seasonal and vertical spatial variation characteristics of total N, NH4+—N and NO3-—N in the soil in Picea mongolica forest at different stand ages were studied. The results showed that: (1) NH4+ —N in the soil in Picea mongolica forest was positively correlated with sample date, soil NO3-—N and forest age (P <0.05), and negatively correlated with soil depth (P < 0.01). NO3-—N in the soil in Picea mongolica forest was negatively correlated with sample date and forest age (P < 0.05), and significantly negatively correlated with soil depth (P < 0.01); (2) the content of NH4+—N is greater than that of NO3-—N in each soil layer of Picea mongolica forest at three forest ages. The correlation analysis showed which had an impact on the content of NH4+—N and NO3-—N in the soil in Picea mongolica forest. The content was lower in February and November, and higher in May and August；(3) The contents of total N, NH4+—N and NO3-—N in the soil of Picea mongolica forest in the three forest ages increased with the depth of soil layer (0-50cm), and showed an overall downward trend. The contents of NH4+—N in the soil layer of young forest (0-10cm, 10-20cm and 20-30cm, 30-40cm and 40-50cm) were significantly different (P＜0.05), and the contents of NO3-—N were also significantly different (P＜0.05), while their contents of middle-aged forest and near mature forest increased with the depth of soil layer, There was no significant difference in the content of NH4+—N; (4) The content of NH4+—N in the soil in Picea mongolica forest generally showed the following change trend near mature forest > middle-aged forest > young forest. The change trend of soil NO3-—N content is consistent with that of the content of NH4+—N in the soil in Picea mongolica forest.

Under the background of the global “polycrisis”, enhancing ecological resilience has become a key pathway for achieving sustainable urban development, particularly in ecologically fragile regions. This study takes the Loess Plateau as the study area and constructs an evaluation framework for urban ecological resilience based on three dimensions: resistance, adaptability, and recovery. By integrating multi-source data from 1990 to 2020, the spatiotemporal evolution of urban ecological resilience in the region is analyzed, and the Geodetector is employed to identify the impacts of natural, economic, and social factors on urban ecological resilience. The main findings are as follows: (1) The urban ecological resilience index on the Loess Plateau shows an overall trend of initial increase followed by decline. Cities in both the western and eastern parts exhibit similar evolutionary patterns, while cities in the central region demonstrate a continuous upward trend, with the resilience index increasing from 0.3658 in 1990 to 0.3838 in 2020. (2) Urban ecological resilience in the study area exhibits a spatial gradient pattern characterized by a decrease from core cities toward peripheral areas. Resilience levels gradually weaken outward from urban centers. The spatial agglomeration effect is relatively weak, with most regions showing insignificant clustering and lacking contiguous high-resilience clusters. (3) Urban ecological resilience on the Loess Plateau is jointly influenced by multiple factors, with the effects of key drivers displaying clear stage-specific characteristics. Socioeconomic factors—particularly population density, per capita GDP, and industrial structure—serve as the primary driving forces, while natural conditions provide basic constraints. Interactions among factors are dominated by bivariate interactions and nonlinear synergistic effects. These findings deepen the understanding of the evolution and driving mechanisms of urban ecological resilience in ecologically fragile regions and provide scientific support for enhancing urban resilience and promoting sustainable development in the Loess Plateau.

To elucidate the mechanisms of nutrient cycling in rhizosphere soil and microbial metabolism during the prolonged continuous cropping of lavender, this study examined the rhizosphere soil of lavender with different continuous cropping years (1, 4, 7, 10, 15, and 20 years) in the Ili River Valley of Xinjiang, China, measuring physicochemical properties, microbial biomass C/N/P, and eight extracellular enzyme activities. Microbial carbon use efficiency (CUE) and nutrient limitation were quantified using vector analysis, threshold elemental ratios (TERs), and two derived indices (TER_EEA and TER_L). Soil properties exhibited distinct nonlinear patterns: SOC peaked at 4 years (p < 0.05), TN was highest at 20 years, and TP was lowest at 4–7 years. MBC and MBN peaked at 20 years, whereas MBP was significantly lower than in 1-, 4-, and 10-year fields (p < 0.05). EEC and EEN were highest at 20 years, while EEP was lowest at 4 years (p < 0.05). The activity of carbon-related acquisition enzymes increases from 134.81 μmol/g·h in the first year to 393.86 μmol/g·h in the 20th year, an increase of 192%; the activity of nitrogen acquisition enzymes increases from 686.11 μmol/g·h in the first year to 1430.58 μmol/g·h in the 20th year, an increase of 108%. This indicates that the decomposition of organic matter and the nutrient cycling capacity continue to enhance. Vector analysis showed a mean VA of 46° and VL of 0.25, with VA > 45° (P limitation) at 1–4 years shifting to VA < 45° (N limitation) at 20 years. Critically, TEREEA and TERL produced opposite dominant limitations due to differing normalization frameworks—TEREEA scales by microbial biomass stoichiometry—while TERL normalizes against enzyme-derived thresholds. CUET and CUEE ranged from 0.42 to 0.56, with the minimum at 10 years and relatively high values at 15–20 years (p < 0.05). RDA identified CBH (26.2%) and NO₃⁻–N (19.8%) as primary drivers, with extractable phosphorus exhibiting the strongest regulatory effect (pseudo-F = 26.0). These results demonstrate that multi-model stoichiometric assessment is essential, as single indices may yield contradictory diagnoses. These results demonstrate that multi-model stoichiometric assessment is essential, as single indices may yield contradictory diagnoses, and the observed nonlinear shifts in dominant limitation type provide a mechanistic basis for targeted nutrient management in sustainable lavender cultivation.

Plastic mulching is considered as a simple, yet effective land management measure to modify microclimate in semi-arid areas. However, the influence of plastic mulching on local soil nematodes and soil quality needs to be investigated more deeply. To fill the knowledge gap, we compared the characteristics of soil nematode communities (density, trophic structure), soil enzyme activities, soil physicochemical properties, and their relationships between maize fields cultivated with use of plastic film mulching and no film mulching, under the same land conditions in Chifeng region, Inner Mongolia. The results showed that the total number of nematodes in most of the film mulched (FM) fields was lower than in no film mulched (nFM) fields. Most of soil chemical properties showed no significant difference between nFM samples and FM samples. Only 0–10 cm soil layer in nFM samples had significantly higher urease activity than in FM samples in June. Plastic film mulching may have an adverse effect on soil quality. Thus, the correct and effective use of plastic film mulch is one of the important measures for future agricultural development in semiarid areas.