Bingcheng Xu

Introduction: Hyperspectral techniques enable rapid non‐destructive prediction of vegetation characteristics, offering an effective method for monitoring grassland restoration status. There are still gaps in the utilization of field hyperspectral techniques to assess the specific grassland characteristics on the Loess Plateau. Objectives: This study aimed to develop a predictive model for spectral parameters and community characteristics of restored grasslands using hyperspectral techniques, providing a feasible method for monitoring grassland restoration status. Methods: A field spectrometer was applied to collect spectral parameters of visible, red‐edge, and near‐infrared (NIR) wavebands, and 16 vegetation indices (VIs) were calculated. A field investigation was conducted on community structural characteristics, functional traits, and aboveground biomass (AGB). Results: Grassland community diversity and height were primarily correlated with the blue‐violet and NIR wavebands. The red and blue‐violet wavebands exhibited the highest sensitivity to canopy pigment content. The red‐edge and visible wavebands were the most critical for estimating grassland community AGB and canopy water content. The dominance of soil‐adjusted indices (e.g. Optimized Soil Adjusted Vegetation Index, Modified Soil Adjusted Vegetation Index) could effectively estimate canopy coverage, water content, and AGB. Significant indirect relationships were observed between VIs and AGB. Conclusions: The optimized prediction model was developed using field hyperspectral techniques, highlighting the mediating roles of community structure and functional traits in predicting biomass from vegetation indices.

Cellulose, a major component of plant cell walls and a critical bioeconomy resource, is synthesized by cellulose synthase complexes (CSCs). Understanding the assembly and function of CSCs, driven by cellulose synthase (CESA) proteins, is essential for enhancing biomass and tailoring cellulose properties for various applications. This study integrates evolutionary analysis, structural modeling, and functional data to elucidate the sequence‐structure–function relationships of CESAs. We analyzed key interface residues within plant‐conserved regions, transmembrane helices, and zinc‐finger domains, revealing functional specialization through variations among duplicated CESAs, subfamilies, and plant groups. Our findings indicate that CESA gene duplication and interface residue divergence, coupled with tissue‐specific and environment‐dependent expression and post‐translational modifications, drive CSC diversification. These alterations in CESAs may redefine CSC assembly. Heterologous expression of an evolutionarily distant CESA, such as Sorghum bicolor secondary wall CESA8 in Arabidopsis, may favor the formation of exogenous homomeric CSCs, leading to increased cellulose synthesis and enhanced plant growth. This increase in cellulose synthesis is associated with pectin demethylation, a process known to promote plant cell expansion. Based on these findings and previous studies, we propose a working model for enhanced biomass production. In this model, interface alterations in CESAs redefine CSC assembly, allowing overexpressed CESAs to form homomeric complexes that enhance cellulosic biomass production.

Saline soil is an important inorganic carbon pool and is highly susceptible to environmental change. The Tarim Basin is the largest inland basin around the world, with saline land making up approximately 20% of its total area, while few research has been conducted on salt‐affected soil carbon density and its distribution in the region. To identify the effect of soil salinity on soil carbon density, we collected 135 soil profiles (0–100 cm), and calculated the soil organic carbon density (SOCD), soil inorganic carbon density (SICD), soil total carbon density (STCD) and their distribution, and discussed their relationships with climate and soil physicochemical properties. Results showed that average STCD, SOCD, and SICD at 0–100 cm soil profile were 25.0, 3.7, and 21.3 kg C m⁻², respectively. SICD was approximately 6.30–9.04 times higher than SOCD. The vertical distribution of SOCD decreased with increasing soil depth, whereas STCD and SICD increased. Soil salinity had negative effects on STCD by reducing both SOCD and SICD, with the negative impact increasing with salinity degrees. Compared to non‐salinity, STCD at 0–100 cm soil profile decreased by 10.5%, 7.0% and 10.5% under light, moderate, and severe salinity, respectively. Random forest analysis indicated that soil total nitrogen content (STN) and soil bulk density (BD) were the most important predictor variables for estimating SOCD and SICD. Soil salinity had significant negative correlation with STN and BD, resulting in a negative effect on SOCD and SICD. Our findings emphasized that soil salinity reduced STCD mainly by reducing SICD, and the reduction in carbon stocks increased with increasing soil salinity degree. In addition, mitigation of the adverse effects of soil salinity on STC stocks could be considered by increasing STN content and soil bulk density.

Understanding spatiotemporal variation in diversity and identifying key external affecting factors are essential for biodiversity conservation. However, community assembly and species diversity in natural grassland (NG) restoration on the Loess Plateau remain unclear. In this study, we examined α diversity (species richness), β diversity (βtotal), and its components (βrepl and βrich) across 89 grassland communities, which were categorized into five restoration stages: recent grassland (RG), early restoration (ER), middle restoration (MR), later restoration (LR), and NG. Linear mixed models (LMM) were used to analyze the effects of topographic, soil, and landscape factors on diversity. Results showed that α diversity followed an increasing‐decreasing trend across restoration stages (7–21 species m⁻²), peaking at the MR stage. In contrast, β diversity and its two components declined with duration, with βtotal and βrepl being notably higher in ER than in LR and NG. Differences in βtotal primarily resulted from species replacement (βrepl, 61%–70%), with a smaller contribution from species gain and loss (βrich, 30%–39%). The LMM also revealed that restoration stage was the most important factor affecting plant diversity, explaining 59.3%, 68.4%, 53.5%, and 58.8% of richness, βtotal, βrepl, and βrich, respectively. In comparison, landscape had weaker effects on diversity (17.2%, 24.2%, 46.5%, 39.8%), while topography and soil factors had the least effects. In summary, deterministic processes (restoration stage) dominate natural restoration, but substantial differences persist between restoration grassland and NG. This study provides valuable insights for assessing restoration progress, prioritizing conservation areas, and informing future grassland management in semi‐arid and fragmented regions.

Quantification of autotrophic (Ra) and heterotrophic (Rh) components of soil respiration (Rs) could greatly improve our understanding of terrestrial carbon cycling. Here, we investigated the effect of nitrogen (N) and phosphorus (P) supply on soil respiration rates and its components, and seasonal cumulative soil CO₂ efflux in a semiarid grassland. A two‐factor experiment of N (0, 50 and 100 kg N ha⁻¹ yr⁻¹) and P (0, 18 and 36 kg P ha⁻¹ yr⁻¹) supply was conducted on the Loess Plateau in 2018–2021. Our results indicated that the promoting effect of combination of N and P supply on soil respiration and its components was greater than that of N/P supply alone. N and/or P supply increased the cumulative soil CO₂ efflux in both non‐growing and growing seasons, and the non‐growing season CO₂ efflux accounted for ∼25% of the growing season CO₂ efflux. The increase of cumulative CO₂ efflux from Ra in response to N and/or P supply was significantly greater than that of Rh in 2018 and 2019, while it shifted to the opposite, that is, a greater increase in Rh than in Ra in 2020 and 2021. Our results suggest that 100 kg N ha⁻¹ yr⁻¹ supply alone is an optimum fertilization scheme to trade‐off grassland productivity and soil CO₂ emissions. Our results highlighted that the promoting effects of N and P fertilization on different soil CO₂ efflux components could be reversed in a relatively short period (4 years), and this should be considered when nutrient addition is adapted to restore degraded grasslands.