Hulunbuir University

Grassland aboveground biomass (AGB) is a key indicator of grassland ecosystem structure and function, and its accurate monitoring is of great importance for assessing grassland ecological conditions and supporting sustainable grassland management. Traditional biomass estimation methods based on vegetation indices (VIs) often suffer from saturation due to canopy shading. However, comparative studies on VI saturation and the saturation height of AGB detectable by different indices remain limited. In this study, we evaluated 12 commonly used VIs based on field-measured AGB and hyperspectral data in the Hulunbuir meadow steppe. Relationships between vertically accumulated biomass and VIs were analyzed to identify optimal AGB fitting models and to determine the saturation height of each index. Results showed that vertical distribution of AGB followed a unimodal pattern, with biomass peaking at approximately 36 cm in this region. This study employed four models (namely the Linear model, the Logarithmic model, the Power Function model and the Gompertz model) to fit the relationship between the vegetation index and AGB. Among them, Gompertz models consistently outperformed other models, indicating saturation across all indices. Based on saturation height, the 12 VIs were classified into two groups: ARVI, GNDVI, NDRE, OSAVI, and SAVI saturated at 40 cm, whereas DVI, EVI, MSAVI, NDPI, NDVI, RVI, and VARI maintained sensitivity up to 50 cm, demonstrating a stronger anti-saturation capacity. NDVI and NDPI exhibited the highest fitting accuracy and resistance to saturation. These findings validate the saturation limitations of VIs and provide guidance for selecting appropriate indices to improve the accuracy of grassland biomass retrieval.

Pinus sylvestris var. mongolica is one of the main afforestation tree species in North China, with significant ecological and economic value (Zhang et al. 2025). In June 2025, we observed irregularly distributed red bands on the needles of P. sylvestris var. mongolica in Toudaoqiao Forest Farm (48.275750°N, 120.000670°E), Inner Mongolia, China, which seriously restricted the local ecological construction. Initially, red bands appear on the needles, followed by gradual chlorosis, eventually leading to extensive wilting. Almost 55% of the trees in the planting area were symptomatic. Randomly collected 30 symptomatic needles from different plants. These samples were cut into 3 mm pieces, surface-sterilized in 75% alcohol for 30 s. After rinsing thrice in sterile distilled water and drying, the pieces were transferred onto potato dextrose agar (PDA) and incubated at 25 ℃ for 5 days. A total of 16 morphologically similar isolates were obtained. Initially, the colonies of the fungi appeared white, after 10 days of cultivation, the mycelium gradually turned orange from the center of the colony, white conidia were evenly distributed outward. Under the microscope, the spores appeared transparent, oval to oblong, without septa. These morphological features align with the typical features of Thyronectria pinicola (Carnegie et al. 2015; Zapata. 2017). The genomic DNA of two representative isolates (NEFU-ZQY-1 and NEFU-ZQY-2) were extracted using the Fungal DNA Extraction Kit (D3390-01, OMEGA, Norcross, GA). The internal transcribed spacer (ITS) , large subunit (LSU) regions of nuclear ribosomal DNA and β-tubulin (TUB2) gene were amplified with ITS1/ITS4, NL1/NL4 (Carnegie et al. 2015) and Bt2a/Bt2b (Wang et al. 2023), respectively BLAST search results showed a homology of over 99% with T. pinicola, with a maximum homology of 100% (KY514388.1, 501/503; KP751377.1, 521/521; JF832863.1, 486/486). The sequences of ITS, LSU and tub2 were deposited in GenBank (NEFU-ZQY-1: PX589408, PX589416 and PX609846; NEFU-ZQY-2: PX589411, PX589417 and PX609847). Moreover, a phylogenetic tree based on the three genes revealed that all two isolates were closest to T. pinicola. Based on these results, the two isolates were identified as T. pinicola. To confirm pathogenicity, healthy trees of 3-year-old P. sylvestris var. mongolica were surface sterilized, healthy needles were punctured with sterile needles, and the spore suspensions (10 7 conidia/ml) of NEFU-ZQY-1 was sprayed onto the damaged needles (n=5). A control group was also established, where sterile water was sprayed instead of the conidial suspension (n=5). The seedlings were then placed in a greenhouse at 25°C. After thirty days, the inoculated plants showed symptoms similar to those of the original infected plant, whereas the control showed no symptoms. The fungus reisolated was morphologically identical to the original isolate, satisfying Koch's hypothesis. There have been reports indicating that a canker disease caused by T. pinicola on Pinus bungeana (He. et al. 2016). To our knowledge, this is the first report of needle blight on P. sylvestris var. mongolica caused by T. pinicola in Inner Mongolia, China. The voucher specimens were deposited in the Heilongjiang Province Key Laboratory of Forest Protection. Honghua'erji Scots Pine Forest is the largest sandy land Scots pine forest in Asia. Those studies could help develop effective measures to prevent and control this disease.

This paper analyzes a homogeneous reaction-diffusion plant-herbivore system incorporating a discrete time delay and a nonlinear toxin-driven functional response. We establish the existence of spatially homogeneous periodic solutions via Hopf bifurcation and investigate the stability as well as the Turing instability of these Hopf-bifurcating periodic solutions. In particular, we derive explicit sufficient conditions expressed through the diffusion coefficients, the critical Hopf bifurcation values, and the first Lyapunov coefficients to characterize the Turing instability of the Hopf-bifurcating periodic solutions.

ABSTRACT Triaxial loading and unloading tests on sandstone samples were conducted under various stress paths to investigate the mechanical properties and energy evolution during rock deformation. The results show a positive correlation between the peak strength and peak strain of sandstone and confining pressure. Both the elastic modulus and Poisson's ratio also increase with confining pressure. Notably, the peak strength and peak strain are minimised under conditions of constant axial stress (CAS) while unloading confining pressure (UCP). For different stress paths, sandstone primarily stores elastic energy with minimal energy dissipation during the initial loading stage, while the proportion of dissipated energy increases with rising confining pressure. During the weakening stage, the threshold value gradually decreases to below 80%, leading to a gradual transformation from rock brittleness to ductility. Under conventional triaxial compression (CTC), rock failure predominantly occurs through shear failure. In the involving increasing axial stress (IAS) while UCP test, a complex tensile‐shear mixed failure mode is observed, whereas no main shear plane forms under CAS‐UCP. Sandstone predominantly undergoes tensile failure under cyclic loading and unloading (CLU). Additionally, an increased loading rate inhibits the initiation and propagation of internal cracks in sandstone at the early stage but promotes damage during the damage development and accelerated development stages. Therefore, hydraulic fracturing design must concurrently account for both tensile and shear fracture mechanisms, with precision optimisation of operational parameters to maximise fracture network complexity.

The high prevalence of tuberculosis (TB) and hypertension in Sepanjang Jaya Village, Bekasi, coupled with limited access to health information, prompted the implementation of this community service program. The aim was to improve health literacy, promote the consumption of nutrient-rich local functional foods, and encourage physical activity. A community-based approach was employed, actively involving participants from the initial assessment to implementation and evaluation stages. The activities included: a pre-test and baseline health screening, interactive health education sessions, demonstrations of pumpkin pudding and roselle-ginger tea preparation, group hypertension exercise, a post-test, data analysis, and both formative and summative evaluations. The results indicated a significant improvement in participants’ knowledge scores (from 10–22 to 35–45) and an increase in the proportion of participants with normal blood pressure (from 29% to 69%). However, 74% of participants still exhibited above-normal blood glucose levels. Most participants (92.5%) reported that the program was beneficial and expressed commitment to applying the knowledge gained. In conclusion, participatory community-based health education combined with local functional food utilization proved effective in enhancing health literacy and improving blood pressure control, while sustained support is required for optimal blood glucose management.

As self-determination theory postulated, motivation has a close relationship with human behaviour. However, in second language (L2) acquisition context, the pattern of L2 motivation influencing students’ behaviour in learning and the role of foreign language enjoyment (FLE) in this relationship are still unclear. Therefore, taking FLE as mediator, this study aims to explore the mechanism of L2 motivation impacting learning engagement among Chinese college students. Participants were 300 college students from China. A structural equation model was constructed using AMOS 28.0. Results showed that both L2 motivation and FLE are significant predictor of students’ learning engagement, and FLE partially mediates the relationship between L2 motivation and learning engagement. The findings of this study emphasize the important role of L2 motivation and enjoyment in Chinse college students English learning. Theoretical and practical implications for educators and English teachers were discussed.