Search Results (3,825)

The dynamics of aboveground biomass (AGB) in rubber plantations (RPs) provide an important basis for evaluating carbon stocks and environmental adaptability in tropical plantations. However, continuous monitoring of AGB of RPs at the regional scale is lacking, and its nonlinear responses to hydrothermal conditions remain insufficiently understood. This study focused on RPs in western Hainan Island (WHI), including Danzhou, Baisha, Lingao, and Chengmai, and integrated field plot data with multi-source remote sensing datasets. A framework for mapping RPs combining rule-based constraints and phenology-based random forest (RF) classification was developed. After key variable screening, extreme gradient boosting (XGBoost), Shapley additive explanations (SHAP), and generalized additive model (GAM) were used for AGB estimation and identification of climatic responses. The results showed that mapping of RPs achieved an overall accuracy of 92.89% and a Kappa coefficient of 0.854. The XGBoost-derived estimates showed that AGB of RPs in the study area increased by approximately 1.43 × 10⁶ Mg from 2017 to 2025, with growth areas mainly concentrated in the Danzhou–Baisha and western Chengmai. AGB exhibited significant nonlinear responses to climatic factors. Specifically, the effect of precipitation (PRE) shifted to negative after approximately 1945 mm yr⁻¹, whereas annual mean maximum temperature (TMAX) shifted to a positive effect after about 29.72 °C, although this effect gradually weakened as temperature continued to rise. Combinations such as PRE × annual mean temperature (PRE × TMP), PRE × TMAX, and PRE × potential evapotranspiration (PRE × PET) exhibited significant nonlinear interactions, indicating that the direction and magnitude of the effect of PRE shifted with changes in temperature and PET levels. These findings link the spatiotemporal changes in AGB of RPs in WHI with hydrothermal thresholds and their interacting effects, deepening our understanding of the climatic response characteristics of AGB in RPs in this region. They also provide a scientific basis for RP monitoring, carbon stock assessment, and climate-adaptive management in WHI. Full article

Chemical harvest aids facilitate mechanical cotton harvesting, but their potential carryover effects on succeeding wheat remain uncertain. Two independent site-year field experiments were conducted in Beijing during 2021–2022 and in Hejian, Hebei Province, during 2022–2023. Experiment 1 compared a freshwater control with preceding Xinsaili applications at 1500 and 3000 g ha⁻¹, whereas Experiment 2 evaluated five biochar treatments under preceding freshwater or Xinsaili application at 1575 g ha⁻¹. In Experiment 1, Xinsaili reduced early aboveground biomass and soil bacterial, fungal, and actinomycete abundance. At 3000 g ha⁻¹, grain number per spike and grain yield decreased by 12.2% and 24.0%, respectively, relative to the water control. In Experiment 2, Xinsaili reduced mean and maximum grain-filling rates by 3.2% and 4.3%, respectively. For the biochar main effect, maize-straw biochar at 750 and 1500 kg ha⁻¹ and rice-husk biochar at 1500 kg ha⁻¹ increased the initial grain-filling potential from 0.25 mg grain⁻¹ without biochar to 0.38–0.42 mg grain⁻¹, with high-rate maize-straw biochar producing the greatest increase. Although Xinsaili × biochar interactions were significant for both grain-filling rates, no biochar treatment significantly improved either rate under Xinsaili application. The grain-filling responses were not consistent between the two independent experiments, potentially reflecting differences in site, year, wheat cultivar, Xinsaili application rate, and experimental design. Thidiazuron and ethephon residues were not quantified in soil or plant tissues; therefore, the observed responses represent indirect field evidence and do not demonstrate either residue-mediated effects or biochar-mediated remediation. Overall, preceding Xinsaili application was associated with treatment- and site-year-dependent wheat responses, while the capacity of biochar to improve final grain yield was not confirmed. Full article

Soybean production commonly faces challenges including severe pod abscission, incomplete seed filling, and uncoordinated source–sink relationships that limit yield potential. Plant growth regulator application may influence source–sink relationships and thereby affect soybean (Glycine max (L.) Merr.) yield formation. This three-year field study (2023–2025) evaluated the effects of four spray programs on soybean yield, quality, total above-ground biomass partitioning, and endogenous hormone dynamics under Xinjiang’s irrigated production conditions. The four treatments were an untreated control (CK), naphthaleneacetic acid alone (NAA; 300 g ha⁻¹), naphthaleneacetic acid plus prohexadione-calcium (NPC; 300 + 450 g ha⁻¹), and naphthaleneacetic acid plus prohexadione-calcium and iron chlorin e6 (NCE; 300 + 450 + 45 g ha⁻¹). The spray programs were applied at the fourth-trifoliolate and full-pod stages. Results showed that NCE treatment consistently produced the greatest yield increases (13.1–14.4%) compared with the control. This response was associated with greater middle-node pod retention, increased 100-seed weight (3.6–6.4%), and improved reproductive organ biomass allocation (44.7–53.3% at maturity vs. 40.9–45.7% in controls). NCE significantly elevated leaf trans-zeatin content (37.1–91.9%) within 24 h after application and improved seed protein concentration by up to 11.2%, while seed residues of all applied compounds remained well below safety thresholds (<0.05 mg kg⁻¹). Correlation analysis revealed strong positive relationships between trans-zeatin levels and both reproductive biomass allocation (r = 0.74–0.90, p < 0.01) and grain yield (r = 0.86–0.96, p < 0.01). These findings indicate that NCE was the best-performing of the four tested spray programs under Xinjiang’s irrigated production conditions, although the individual contributions and possible interactions of the three compounds require further factorial evaluation. Full article

Mangroves are important coastal blue-carbon ecosystems, and accurate biomass estimation is essential for carbon stock assessment and ecological monitoring. To address the limitation of regional-scale biomass estimation caused by the scale mismatch between field plots and satellite pixels, this study selected the Zhangjiangkou National Mangrove Nature Reserve in Fujian Province as the study area and the mangrove distribution region of Fujian Province as the extrapolation area. A multiscale biomass estimation framework integrating field plots, unmanned aerial vehicles (UAVs), and satellite remote sensing was established. The results showed that (1) the optimal UAV-scale models achieved R² values of 0.69 and 0.78 for aboveground biomass (AGB) and belowground biomass (BGB), respectively, with corresponding root mean square error (RMSE) values of 18.55 and 9.52 t·ha⁻¹ and normalized root mean square error (nRMSE) values of 0.14 and 0.17 demonstrating reliable predictive performance; (2) after introducing UAV-derived bridging labels, the R² of the AGB model increased from 0.24 to 0.64, while the RMSE decreased from 29.02 to 10.86 t·ha⁻¹. Similarly, the R² of the BGB model increased from 0.43 to 0.63, accompanied by a reduction in RMSE from 14.89 to 6.35 t·ha⁻¹, demonstrating a substantial improvement in satellite-scale biomass estimation accuracy; (3) the total AGB and BGB of mangroves in Fujian Province were estimated at 58,768.60 t and 24,575.14 t, respectively, with high-biomass areas mainly distributed along the coastal regions of Zhangzhou and Quanzhou. Unlike conventional field-to-satellite extrapolation approaches, the proposed framework introduces UAV-derived biomass maps as intermediate bridging labels for pixel-level supervised learning, thereby establishing an effective link between field measurements and satellite observations. This strategy effectively reduces the scale mismatch between field and satellite data, significantly improves satellite-scale biomass estimation accuracy, and provides a transferable and scalable framework for regional mangrove biomass mapping and blue-carbon assessment. Full article

Urban green open spaces play a critical role in mitigating greenhouse gas emissions and enhancing biodiversity in rapidly urbanizing tropical megacities. This study aims to characterize vegetation structure and species diversity, as well as quantify above-ground carbon stocks in Taman Bendera Pusaka, South Jakarta, Indonesia. The results are expected to inform evaluations of urban parks’ contribution as nature-based solutions. A complete tree census was conducted between August and September 2025, recording diameter at breast height, height, and species identity for all individuals. Above-ground biomass (AGB) for woody trees was estimated using a widely applied pantropical allometric model developed for humid tropical forests, while separate generalized equations were applied respectively to the palms and bamboos groups to account for their distinct morphological characteristics. The estimated biomass values were subsequently converted into carbon stocks and CO₂ equivalents. Biodiversity was evaluated using Margalef richness, Shannon–Wiener diversity, and Pielou’s evenness indices. A total of 2459 individuals were recorded. Langsat Park had the highest species richness (S = 79) with diversity (H′ = 3.38; E = 0.77), and Leuser (S = 78) with highest diversity (H′ = 3.44; E = 0.79), whereas Ayodya Parks showed the lowest structures and diversity values (S = 33; H′ = 2.18; E = 0.68). Total AGB reached 5873.63 Mg, with a mean carbon density of 444.64 Mg C ha⁻¹ or 1631.82 Mg CO₂ ha⁻¹. Carbon storage was largely driven by a few dominant ornamental palms, particularly Roystonea regia, although native canopy trees contributed to structural stability. These findings show that even relatively small tropical urban parks can serve as significant localized carbon storage while sustaining urban biodiversity, underscoring the value of structurally diverse, native-enriched planting strategies for resilient urban forest management. Full article

Dwarf cereal cultivars were crucial for the Green Revolution. Dwarfed, lodging-resistant varieties remain essential today, as climate change brings more storms and downpours. In barley, the dwarfing gene HvDEP1 has been widely used in breeding. Although its pleiotropic effects on agronomic traits have been examined, previous studies relied on cultivars developed via random mutagenesis, which carry background mutations that may influence phenotypes. Moreover, its impact on root traits remains underexplored. We used CRISPR/Cas9 to generate precise HvDEP1 mutants and introduce dwarfism into the barley cultivar ‘Maythorpe.’ We assessed the effects on above-ground morphology, yield-related traits, root architecture, biomass via ¹³C labelling, and the root metabolome. HvDEP1 mutations significantly reduced plant height, straw, spike, and awn length, as well as thousand-grain weight. An in-frame mutant showed intermediate height, straw, and awn phenotypes. Belowground, in a root experiment restricted to knockout line #12, specific root length and the length of the finest (0–0.25 mm) roots were reduced, while total root length was lower but not significantly so; (p = 0.062). Root metabolomic profiling detected no genotype-associated differences. These results provide new insights into HvDEP1′s role in both shoot and root systems and demonstrate that precise CRISPR/Cas9-mediated editing can rapidly introduce dwarfism while revealing trade-offs in other agronomic traits. Full article

Tropical mining landscapes require plot-based structural and carbon baselines to support restoration planning and environmental monitoring. This study estimated aboveground, root, and total tree carbon stocks across six mining concessions located in the Inambari River basin, Madre de Dios, southeastern Peruvian Amazon. Field inventories were conducted in 39 plots of 0.1 ha, where all trees with DBH ≥ 10 cm were measured. Aboveground biomass was estimated using a pantropical allometric equation based on wood density, diameter, and height; root biomass was estimated using a baseline root-to-shoot ratio of 0.24; and biomass was converted to carbon using a baseline carbon fraction of 0.47. Structural attributes, biomass stocks, carbon stocks, diameter-size profiles, basal-area contribution by diameter class, and multivariate structural-carbon patterns were evaluated among concessions. The concessions differed significantly in measured structural attributes, and these differences translated into contrasting derived biomass and tree carbon estimates. Edmilot I showed the highest basal area per hectare, total biomass, and total tree carbon, reaching 118.34 Mg C ha⁻¹, while Yesica recorded the lowest total tree carbon, with 58.54 Mg C ha⁻¹. Most trees were concentrated in the 10–20 cm and 20–30 cm DBH classes, but intermediate and larger trees contributed disproportionately to basal area. Principal component analysis summarized the concessions according to a reduced set of non-redundant structural and carbon variables, with the first two components explaining 99.21% of the total variation. These findings show that mining concessions retain contrasting forest conditions and should not be treated as homogeneous units. Structural and carbon baselines can help identify internal differences among concessions, prioritize restoration actions, and improve environmental monitoring in tropical mining landscapes. Full article

Heavy metal deposition along high-traffic roadsides poses a persistent threat to agricultural safety, yet the partition barrier efficiency across rhizosphere–root–shoot interfaces in perennial nut crops remains poorly understood, representing a significant research gap. This study determined the concentrations of potentially toxic elements in the rhizosphere soils and distinct organs (leaves, pericarp, and edible seeds) of Siirt pistachio trees along a distance gradient (0, 50, and 100 m, plus a control site) in the Siirt and Tillo districts. To filter analytical baseline noise, all raw datasets were subjected to strict solid-matrix limit of detection (LOD) screening using a standardized dilution factor of 30 mL/g (DF = 15 mL final volume/0.5 g sample mass). Soil analysis revealed that the alkaline pH (6.90–7.27) and highly calcareous nature (21.97–65.75%) of the rhizosphere acted as a powerful edaphic barrier, immobilizing metals in the soil and limiting their translocation to aboveground tissues. Plant accumulation followed a leaf > pericarp > seed hierarchy, proving the canopy’s role as an effective vegetative filter. Crucially for food safety, highly toxic Cd (<1.74 µg/kg) and Bi remained entirely below detection limits in edible seeds. Cr peaked in leaves (730.42–795.00 µg/kg) but was highly restricted in seeds. Detected kernel concentrations of As, Co, Ni, Pb, and Sb were strictly below international toxic thresholds, while essential Cu physiologically concentrated in seeds and leaves. Consequently, the cumulative Hazard Index (HI) remained exceptionally below the 1.0 critical safety limit for both adults (<0.18) and children (<0.32). This confirms that roadside pistachios pose zero non-carcinogenic health hazards and are completely safe for human consumption. Full article

Reliable aboveground biomass (AGB) estimates for woody crops are essential for carbon accounting and for Measurement, Reporting and Verification (MRV) frameworks. However, it remains unclear how LiDAR modality and sampling geometry influence plot-scale and tree-scale AGB predictions in intensively managed Mediterranean orchards. In this study, we benchmarked four LiDAR modalities, namely open national airborne laser scanning from the Spanish National Aerial Orthophotography Plan (PNOA/ALS), a dedicated Riegl airborne laser scanner (ALS), unmanned laser scanning (ULS) and mobile laser scanning (MLS), across three woody-crop sites in Córdoba (southern Spain): IFAPA, Doña María, and Villaseca. Plot-level LiDAR metrics (mean height, 95th height percentile, maximum height, and canopy-cover proxies) were extracted from normalized point clouds and related to field AGB using Random Forest and XGBoost regression models, together with an ensemble predictor, under an 80/20 train–test split. In parallel, TreeQSM-based Quantitative Structure Models (QSMs) were evaluated as an independent tree-level three-dimensional reconstruction approach. XGBoost achieved the lowest errors at IFAPA (RMSE = 0.400 Mg ha⁻¹; R² = 0.994) and Villaseca (RMSE = 0.872 Mg ha⁻¹; R² = 0.995), whereas PNOA/ALS was competitive at Doña María (RMSE = 0.725 Mg ha⁻¹; R² = 0.994). TreeQSM closely matched the field inventory at the low-biomass IFAPA site but tended to overestimate biomass at Doña María and Villaseca, and only 28% of scanned trees yielded usable reconstructions. The results support the use of cross-platform LiDAR for orchard AGB and carbon mapping and identify the conditions under which open national LiDAR can enable scalable MRV of Mediterranean woody crops. Full article

The degradation of Calcisols in the arid regions of Central Asia constrains sustainable agricultural production because of low organic matter content, poor aggregate stability, nutrient limitations, and increasing climatic stress. This study evaluated a rhizosphere engineering approach based on the native plant growth-promoting bacterium Pseudomonas veronii Ps-S/Sh-1503/2022 for the rehabilitation of degraded Calcisols. Four-year field experiments (2022–2025) using Sorghum bicolor assessed plant growth, rhizosphere microbial indicators, physiological responses, pathogen suppression, crop productivity, and implementation feasibility through economic and environmental assessments. Inoculation with P. veronii increased root depth by 45%, improved aboveground biomass, increased the ratio of culturable bacteria to Fusarium spp. from 6.1 to 10.3, and reduced Fusarium abundance by 29.4%. Structural equation modeling suggested that trophic support (42.1%), aggregate stabilization (27.4%), biocontrol (23.3%), and defense-related responses (7.2%) were the principal pathways associated with soil rehabilitation. Economic assessment indicated that the combined inoculation and mineral fertilization treatment provided the highest profitability, while environmental assessment estimated potential reductions in mineral fertilizer use and greenhouse gas emissions. These findings suggest that rhizosphere engineering using a native P. veronii strain represents a promising, economically viable, and climate-smart approach for improving the biological functioning of degraded Calcisols and supporting sustainable agricultural production. Full article

Elucidating patterns of plant biomass allocation is an important subject in ecological research. Broadly speaking, two schools of thought are applied to understand it: allometric partitioning theory (APT) and optimal partitioning theory (OPT). Which theory prevails for the highly aggressive invasive weed Cenchrus pauciflorus regarding intraspecific variability in biomass allocation across habitats has never been studied. Using the R package smatr (Standardised Major Axis Estimation and Testing Routines), we report on allometric relationships regarding biomass allocation in four habitats of the Songnen Plain. There is a large body of literature that has generally considered the allometric coefficient. This study further combined the slope, intercept and shift along the common standardized major axis (SMA) to explain biomass partitioning. We found an isometric relationship between aboveground and root biomasses in three habitats and between stem and root biomasses in two habitats, supporting allometric partitioning theory (APT). Significant differences in slopes between habitats were observed for most relationships. Those habitats whose slopes were not significantly different showed significantly different elevations or shifts in location along a common slope, even for isometric relationships. Such inter-habitat variation suggests that the adjustment of biomass allocation may be induced by environmental conditions, supporting optimal partitioning theory (OPT). It has been suggested that phenotypic integration could constrain trait plasticity; whether this is true remains a debated topic with mixed empirical support. We provide one of the few lines of evidence showing that phenotypic integration is positively associated with the phenotypic plasticity magnitude across advantageous and stressful environments. This study provides insights into the adaptive strategies of invasive Cenchrus pauciflorus in heterogeneous habitats and a scientific basis for habitat-specific management and control. Full article

Accurate aboveground biomass (AGB) estimation in subtropical forests is critical for regional carbon accounting and sustainable forest management. However, standardized multi-source feature screening and integrated machine learning–geostatistical analysis of AGB remain limited. This study integrated six heterogeneous datasets: Landsat-8 optical imagery, Sentinel-1 SAR, topographic, meteorological, soil data and the 2014 National Forest Inventory (NFI), and established 48 predictors in subtropical forests of Anhui Province, China. A two-stage variable selection framework was applied, with Pearson correlation screening reducing the initial 48 predictors to 36 less-correlated variables, followed by the recursive feature elimination (RFE) with 5-fold spatial block cross-validation for further predictor selection. Random Forest (RF), eXtreme Gradient Boosting (XGB), Empirical Bayesian Kriging Regression Prediction (EBKRP), hybrid RF_EBKRP and XGB_EBKRP models were evaluated. Stand age and stand density were dominant predictors in both RF and XGB, contributing 33.6% and 24.0% in RF and 36.5% and 17.3% in XGB, respectively. Elevation, precipitation, and canopy cover showed secondary importance, whereas vegetation indices contributed relatively little. RF_EBKRP achieved the highest prediction accuracy (R² = 0.77), reducing RMSE by 17.20% and 43.75% compared with RF and EBKRP, respectively. This study provides a reproducible RF–EBKRP workflow integrating nonlinear machine-learning prediction with geostatistical residual correction, supporting improved subtropical forest AGB mapping and management. Full article

Mining-affected soils differ markedly in their physicochemical properties and metal loads, complicating the selection of plant material for phytoremediation. This study evaluated Brassica oleracea var. acephala ‘Pigeon’ growth across 14 mining-affected soils and a growth reference commercial substrate, followed by a site-specific pilot field assessment on a selected multi-metal-contaminated soil from Cavnic, Romania. Plant establishment, vegetative performance, pooled plant mass, and metal partitioning were assessed under controlled and field conditions. Plant responses varied strongly among soils, and final germination at 30 days after sowing did not reliably predict subsequent vegetative performance. On the selected Cavnic soil, establishment was lower in the field than under controlled conditions, whereas plants that established in situ attained greater final size. Within the seven selected field-grown plants, root-associated concentrations exceeded aboveground concentrations for Cu, Zn, Pb, and Mn. The results show that multi-soil laboratory screening and field assessment capture complementary biological components of plant performance. Full article

Exploring plant nutrient allocation and stoichiometry is critical to understanding the adaptive strategies of endangered trees in heterogeneous habitats. This study determined the concentrations of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) in seven organs (leaves, current-year twigs, perennial branches, phloem, xylem, transport roots, and absorptive roots) of Parrotia subaequalis from eight wild populations in the Dabie Mountains and then analyzed the stoichiometric characteristics, chemical plasticity, and allometric relationships of these elements among organs. The concentrations of C, N, P, and K ranged from 416.31–513.61, 4.74–12.99, 0.74–12.89, and 2.62–10.34 mg g⁻¹, respectively. Belowground organs had significantly higher C:P, N:P, and N:K ratios than aboveground ones (by 72.83%–740.30%). Perennial organs (xylem, phloem, perennial branches) showed higher C concentrations and C:N, C:P, C:K, and P:K ratios but lower N, P, and K concentrations than current-year ones (leaves, current-year twigs). Xylem, phloem, and perennial branches exhibited the lowest coefficient of variation and plasticity index. N, P, and K exhibited isometric scaling (α = 0.96–1.04) between absorptive and transport roots. Leaf N and P were positively correlated with K (R² ≥ 0.53). Organ age is a critical determinant influencing the variation in stoichiometric characteristics of the organs. Overall, P. subaequalis adapts to nitrogen-limited wild habitats by adjusting N, P, and K nutrient up-take rates and allocation ratios across current-year organs. Full article

Ground-based logging operations cause soil compaction that constrains natural regeneration in the Hyrcanian forests of northern Iran, yet how soil textural properties modulate these effects on endemic tree species remains poorly understood. This study assessed the interactive effects of soil texture and compaction intensity on seedling growth and biomass allocation of Persian honeylocust (Gleditsia caspica Desf.) under controlled conditions. A factorial greenhouse experiment with three soil textures (loam, sandy loam, and silty clay loam) and six compaction levels (0–5 Proctor impacts) was conducted. After a 110-day growing period, morphological traits and biomass partitioning were analyzed using two-way ANOVA. Significant soil texture × compaction interactions (p < 0.05) were found for lateral root length, primary and lateral root dry biomass, stem biomass, total biomass, leaf mass ratio, root mass ratio, and the lateral-to-primary root length ratio. In sandy loam, mild compaction (Level 1) increased total biomass by 39% (2.15 g) and lateral root length by 34% (448.5 cm) relative to the controls, indicating a beneficial compaction window. Loam soils exhibited an initial reduction in growth at low compaction levels, followed by recovery at moderate levels, suggesting physiological acclimation. Silty clay loam, with its high compressibility, suppressed root proliferation and aboveground growth across most compaction treatments. Axial traits, including stem length, primary root length, and root collar diameter, remained stable irrespective of treatment, highlighting a conservative developmental strategy. These results reveal that G. caspica employs a hierarchical adaptive strategy involving dynamic modulation of lateral root development and whole-plant carbon partitioning while preserving core axial architecture. The strong texture dependence of these responses highlights the need for texture-specific forest management. For restoration in degraded Hyrcanian landscapes, soil compaction thresholds should be calibrated to the dominant textural class to avoid exceeding the species’ ecological plasticity. Full article