(1) Background: In recent years, Hippophae rhamnoides has been used extensively to prevent desertification in China due to its nitrogen (N) fixation and sand stabilization abilities. However, as a dioecious species, few studies have focused on the sexual dimorphism of H. rhamnoides in response to sand burial, which frequently presents in desertification areas. (2) Methods: In this paper, we explored the ecophysiological responses of female and male saplings of H. rhamnoides under unburied treatment (control) and different sand burial depths (denoted as T33, T67, T90 and T133, corresponding to sand burial depths of 33, 67, 90 and 133 percent of the mean initial height of the saplings, respectively). (3) Results: Compared with unburied controls, the T33 treatment significantly promoted biomass accumulation and photosynthetic capacity, whereas T67 and T90 treatments inhibited biomass and physiological parameters of the two sexes. Deeper sand burial treatments, i.e., T90 and T133, significantly decreased the survival rates of the two sexes. Furthermore, the sex-specific responses of the two sexes of H. rhamnoides were affected by different depths of sand burial. Males had higher levels of stem starch and root sucrose and exhibited a larger increase in root nodule biomass under the T33 treatment, indicating better carbohydrate utilization and N fixation, whereas females showed lower total biomass and fewer root nodules, as well as more inhibition of photosynthetic and chlorophyll fluorescence parameters, water potential and root carbohydrates, indicating more negative effects on females than males under the T67 treatment. (4) Conclusions: We conclude that sex-related response and adaptation to sand burial depths may potentially affect the colonization, sex ratio and ecological function of the two sexes of H. rhamnoides in desertification areas.

Agriophyllum squarrosum (L.) Moq. is a highly prevalent xerophytic species found throughout northern China. It is suitable for cultivation in semi-arid sandy environments and may establish roots in arid desert locations. This species plays a pioneering and exploratory role in the colonization of desert plants. In this study, we selected A. squarrosum from the Urat desert steppe (UD) and Horqin sandy land (HS) to explore their adaptation mechanisms to drought and rehydration environments by using the pot weighing control method to simulate an arid environment. The findings showed that the control (watering to 60–65% of field capacity) exceeded its required amount and the leaves turned yellow. The chlorophyll content was lower than those under moderate and severe drought, and rehydration caused a decrease. However, the contents of malondialdehyde, soluble sugar, and proline in the drought treatment were higher than those in the control. Under moderate and severe drought, the chlorophyll content and the quantum efficiency of photosystem II (Fv/Fm) of A. squarrosum from UD were higher than those from HS. During drought and rehydration processes, the proline content was relatively lower, while the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) and the content of soluble sugar and soluble protein were higher. However, antioxidant enzymes and osmoregulators from UD were higher than those from HS. The results suggest that the stronger ability of A. squarrosum to endure drought environments in UD is due to the high level of antioxidant enzymes and osmoregulators, which are conducive to relieving cell membrane damage when subjected to drought and rehydration.

Davidia involucrata has an ancient origin, representing a remnant from the paleotropical flora that thrived during the Tertiary period. Altitudinal gradient acts as a natural testing ground for studying climate change, and research on the distribution patterns of microorganisms along altitudinal gradients is crucial in understanding the adaptability of D. involucrata to climate change. In our study, we examined sample sites ranging from 1600 to 2200 m in elevation, which are part of the primary habitat zone for Davidia involucrata within the Xuebaoding National Nature Reserve. In 2021, field surveys were conducted across four altitudinal gradients (1600 m, 1800 m, 2000 m and 2200 m) of the D. involucrata distribution in the nature reserve. The sampling plots were set in each altitudinal gradient, and three representative and healthy mature trees were selected as sample trees for each plot. Rhizosphere soils were used to test the soil stoichiometry characteristics and root zone microbial communities. Our findings indicated pronounced differences in soil total carbon (TC) and total phosphorus (TP) content and C:P and N:P ratios between the four altitude sites (p < 0.05). Analysis of the bacterial communities revealed higher richness (PD and Chao1 indexes) at ASL2000 and ASL2200 (high altitude) compared to ASL1600 and ASL2000 (low altitude) (p < 0.05). Non-metric multidimensional scaling analysis demonstrated a distinct clustering of bacterial communities between the high and low altitudes (p < 0.01). At the phylum level, Proteobacteria and Acidobacteria were predominant at high altitudes, while Actinobacteria and Chloroflexi dominated at low altitudes. The core microbiome, shared among all altitudes, comprised 377 genes. The analysis of differential abundance revealed notable disparities in the prevalence of certain bacterial genera with altitude, with Arthrobacter and Acidothermus experiencing the most pronounced shifts (p < 0.05). This confirmed that environmental factors significantly influenced bacterial community structure and abundance. Spearman’s rank correlations revealed that both Chao1 and PD indices were positively correlated with elevation, TC, and TN, with Chao1 showing stronger relationships. Both indices were negatively correlated with MAT, while only Chao1 exhibited a significant negative correlation with pH. Linear regression analysis further confirmed the significant associations between Chao1 index and elevation, TN, MAT, and pH. Furthermore, redundancy analysis demonstrated that altitude (ASL) and TN were the primary factors shaping soil bacterial community composition, explaining 21.32% and 30.70% of the variance, respectively. Altitude significantly influenced microbial community structure (p = 0.003). Distinct microbial taxa showed specific associations with environmental gradients, suggesting niche specialization in response to soil conditions. These findings suggest that altitude influences soil nutrient characteristics and microbial community composition in the D. involucrata habitat, offering insights into the ecological factors affecting this endangered species.

A new mite species, Aculops schinifolius sp. nov. from Panzhihua, Sichuan Province, southwestern China, is described and illustrated. This new species causes deformed and necrotic fruits (flower-like galls) on Zanthoxylum schinifolium Siebold & Zucc. (Rutaceae). We redescribed Paracolomerus davidiae Kuang & Hong, 1995, which was found making galls on Davidia involucrata Baill. (Nyssaceae) for the first time. We provided mitochondrial cox1 gene sequences for A. schinifolius sp. nov. (PQ492665) and P. davidiae (PQ505669).