This study aimed to enhance the efficiency of genomic prediction for pulpwood-related traits in slash pine (Pinus elliottii Engelm. var. elliottii) by integrating genome-wide association study (GWAS) information with genomic selection (GS). We evaluated 12 traits related to growth, fiber, and wood chemical composition in a population of 340 individuals genotyped with 319,286 high-quality SNPs, comparing the performance of six GS models, including GBLUP and Bayesian methods, under varying training population sizes and marker densities. The results showed that while both GBLUP and Bayesian Lasso performed well, Bayesian Lasso slightly outperformed GBLUP for fiber traits. Predictive ability (PA) plateaued at approximately 100K SNPs for fiber traits, 60K for DBH, and 10K for wood chemical composition traits in all models. Using 100K random SNPs, PA ranged from 0.05 to 0.23, which expanded to 0.09-0.35 with GWAS-guided SNP preselection (maximum improvement of 16.26%) and further broadened to 0.01-0.38 by incorporating large-effect QTLs (greatest improvement of 23.54%). Overall, integrating GWAS information into GS frameworks significantly improved prediction accuracy as assessed by t-test, offering a cost-effective strategy to accelerate genetic improvement. These findings provide practical guidance for enhancing breeding efficiency in slash pine and other conifer breeding programs.

Slash pine (Pinus elliottii) possesses an exceptionally large, repeat-rich genome, and existing low-density SNP arrays provide limited marker coverage and resolution of linkage patterns. To increase marker density for population-based genetic analyses and improve the accuracy of genomic relationship matrix (GRM) estimation, we constructed a reference panel from about 10× whole-genome resequencing of 50 maternal parents and performed genome-wide imputation for 51K SNP-array genotypes of 715 half-sib progeny. Imputation accuracy at array loci was quantified using chromosome-local masking experiments, whereas reference-panel-expanded loci not represented on the array were evaluated for concordance and filtered via external validation using progeny resequencing data. Masking-based concordance remained stable at 95.5%, and after threshold-based filtering of expanded loci, we generated a high-density genotype matrix for all 715 individuals comprising 120,650,180 SNPs. Comparative local linkage disequilibrium (LD) heatmaps indicated more continuous LD signals and clearer block structures after densification; for the Chr4 10.22-10.33 Mb interval, the proportion of high-LD SNP pairs increased from 14.5% to 27.6%. The GRM derived from the densified dataset was highly consistent with the array-based GRM in off-diagonal elements (Pearson's r≈0.984). Distance-stratified analyses further showed higher concordance for GRMs constructed from imputed loci within 500 kb of array markers, with concordance decreasing progressively in more distant windows, suggesting limited incremental benefit from long-range imputed loci. Collectively, the reference panel-driven imputation, validation, and integration framework established here provides a high-density genotypic resource for genome-wide association studies and genomic selection in slash pine and other conifer species.

Legacy effects of simulated acid rain and nitrogen deposition on soil respiration in a Pinus elliottii plantation of subtropical China

Polyphenol oxidase-mediated browning during storage of Pinus elliottii oleoresin: characterization of pine-needle PPO and antibrowning action of L-cysteine

ABSTRACTIn south Florida, climatic variation and ongoing hydrologic alterations are predicted to impact the growth and ecophysiological performance of tree species. Understanding how tree growth rates vary across temporal and landscape‐scales in relation to climate and hydrology will help us better understand and predict how tree species, and thus landscapes will respond to increasing variability in regional climates. Here, we used dendrochronology and stable isotopes (δ13C) to examine tree growth rates and intrinsic water‐use efficiencies (iWUE) of Taxodium ascendens, T. distichum, and Pinus elliottii in relation to climate and hydrology at the southern ends of their distributions. Specifically, we cored 20–26 individuals of each tree species growing in south Florida's Big Cypress National Preserve to estimate annual growth rates and iWUE. From these samples, we built tree‐ring chronologies and determined δ13C. Then we evaluated how both growth rates and iWUE vary with climatic and hydrological conditions through time and across the landscape. Although overall climate–growth correlations were weak, water depth proved influential. Taxodium ascendens and T. distichum grew most rapidly during summers (June–September) when seasonal standing water depths increase. In contrast, P. elliottii grew faster in springs (April–May) when seasonal standing water depths are the lowest. Relative location within the landscape was not an important factor driving tree growth. The iWUE of all species increased significantly with rising mean annual temperature and vapor pressure deficit (VPD), while precipitation and water depth had differential effects on each species' iWUE. Overall, our results highlight the complexity of factors driving tree growth rates and iWUE of these tree species at the southern ends of their distributions, as well as the potential for future climate‐driven changes in tree growth and performance across south Florida's natural ecosystems.

The forestry of Pinus elliottii reached a commercial scale in the mid-1980s in the municipality of São José do Norte, RS, Brazil. With the aid of tax incentives, producers sought income from resin extraction, and the plantations expanded significantly, forming large blocks in the district of Bojuru. This study aimed to evaluate the natural regeneration of pioneer native species following the removal of P. elliottii in a dune area; assess the implementation of vegetative barriers using native species for area restoration and dune protection; and test different techniques for dune stabilization using physical barriers and clustered native plantings. The results of natural regeneration were favorable at the experimental site, unlike the seedling survival rates, which were below the levels considered ideal for restoration purposes. The dune stabilization technique using physical barriers (containment fences) proved effective on the dune crest but did not yield the same results in wet areas or those with pre-established vegetation. Dune areas adjacent to commercial plantations and lacking established vegetation are particularly vulnerable to the spread of P. elliottii seeds.

Accurate, spatially explicit quantification of the fraction of absorbed photosynthetically active radiation (fPAR) in tall conifer plantations is essential for productivity modelling and breeding, yet standard nadir-view optical UAV imagery yields only two-dimensional surface estimates. We developed an unmanned aerial workflow that fuses centimeter resolution LiDAR point clouds with five band multispectral imagery to produce a three-dimensional voxelized canopy structure in which top-of-canopy multispectral reflectance values are propagated downward within each vertical column. Ground measurements of fPAR and chlorophyll fluorescence were collected contemporaneously and used to calibrate Random Forest, XGBoost, Support Vector Machine (SVM), and Partial Least Squares Regression models built from 14 spectral indices. Random Forest explained 84 % of fPAR variance (RMSE = 0.12), outperforming alternative algorithms. Application of the trained Random Forest model to the voxelized canopy (0.01 m × 0.01 m × 2 m) across 28 ha generated three-dimensional fPAR maps that revealed a 26 ± 4 % increase from lower to upper crowns and a seasonal shift of up to 9 %. Compared with conventional plot-level inversion, the workflow significantly reduced field labour and improved prediction accuracy. The fusion pipeline provides a species-specific tool for high-throughput phenotyping, precision silviculture, and genomic selection in slash pine plantations under clear-sky conditions (solar zenith angle 20-30°); transferability to other sites, species, or illumination conditions requires further validation.

Persistent cloud cover and frequent rainfall in subtropical regions throughout the year significantly limit the applicability of optical remote sensing for tree species identification, thereby constraining dynamic forest monitoring and precise management of forest resources. To address this challenge, this study proposes a tree species identification method that integrates multi-source remote sensing temporal features. By combining multi-temporal optical imagery from Sentinel-2 and dual-polarisation Synthetic Aperture Radar (SAR) data from Sentinel-1, we constructed a comprehensive feature set that incorporates spectral, structural, and phenological attributes, including various vegetation indices, backscatter coefficients, and polarimetric decomposition parameters. Through correlation analysis and assessment of temporal feature variability, five distinct integration strategies (T1-T5) were developed to classify six typical subtropical tree species: Pinus massoniana, Pinus elliottii, Acacia, Eucalyptus grandis, Mangrove, and Other hardwoods, using a random forest classifier. The results indicate that the multi-source feature fusion approach significantly outperforms single-source models, with the T5 strategy achieving the highest overall accuracy (OA) of 95.33% and a Kappa coefficient of 0.94. The red-edge vegetation indices and SAR polarimetric features were identified as major contributors to improving the classification accuracy of hardwood species. This study demonstrates that multi-source remote sensing data fusion can effectively mitigate the spatiotemporal constraints of optical imagery, providing a viable solution and technical framework for high-accuracy remote sensing classification in complex subtropical forest environments.

Biodiverse composts obtained through composting are widely used in regenerative agriculture due to their ability to improve soil quality, crop growth, and productivity, primarily by promoting beneficial microorganisms. These composts result from the decomposition of mixtures containing nitrogenous and plant biomass. During plant biomass preparation, litter serves as a source of beneficial microorganisms, which transition from endophytes to decomposers. This study tested the hypothesis that the type of litter influences the composition of bacterial and fungal communities in biodiverse composts, thereby affecting species abundance and diversity. To this end, litter from the tree species Handroanthus impetiginosus (Angiosperm-AC) and Pinus elliottii (Gymnosperm-GC) was evaluated in compost preparation, also investigating the impact of litter type on the concentration of macronutrients, chemical parameters (such as organic carbon, cation exchange capacity-CEC; carbon/nitrogen ratio-C/N; organic matter-OM; pH, and humic substances fractions, including humic and fulvic acids), and microbiological quality (assessed by Microbial Biomass Carbon-MBC). The microbial composition of composts prepared with both AC and GC litter was more influenced by the composting method than by plant origin, with bacterial genera such as Thermobacillus (representing 1.27% and 1.23% of the genera present in AC and GC, respectively) and thermotolerant species, adapted to the high temperatures of the thermophilic phase, being notably present. GC litter favored a higher abundance of bacterial (pi = 0.027) and fungal species (pi = 0.042), despite the antimicrobial properties of P. elliottii. In contrast, AC compost accumulated higher levels of macronutrients and OM (39.5%), reflecting the efficacy of specific fungi in decomposition, particularly species from the phyla Chytridiomycota and Zoopagomycota, identified exclusively in this compost. MBC analysis indicated that composts reach optimal efficiency and nutritional quality between 60 and 90 days of maturation, suggesting that this period is the most suitable for leveraging the resident microbiota and producing high-quality composts for agricultural use.

Forestry activities require accurate inventories to support sustainable forest management; however, conventional field-based inventories are costly and difficult to implement over large areas. This study aimed to define and evaluate a methodology to estimate the number of trees in commercial plantations of Pinus elliottii and Eucalyptus sp. using images acquired by an Unmanned Aerial Vehicle (UAV) in the central region of Rio Grande do Sul, Brazil. The study was conducted in three plantations (P1 – Pinus, 17 ha; P2 and P3 – Eucalyptus, totaling 33 ha). Circular sampling plots of 400 m² were established for the conventional forest inventory. Orthomosaics were generated from UAV flights using a DJI Mavic 3M at 120 m altitude, with 80% forward and 70% side overlap. Circular and rectangular sampling units with the same area were delineated on the images at the same sampling locations. Image processing was performed in Agisoft Metashape, and spatial analysis was conducted in QGIS. Tree counts obtained by the three methods (field inventory, circular plots on imagery, and rectangular plots on imagery) were compared using the Shapiro–Wilk normality test and, when appropriate, Student’s t-test or the Mann–Whitney U test. Statistically significant differences were observed between field-based counts and UAV-derived estimates in all study areas, whereas no significant differences were found between the two image-based methods. Discrepancies were smaller in Pinus plantations and more pronounced in Eucalyptus stands, indicating underestimation related to crown architecture, stand density, crown overlap, and image resolution and illumination constraints. Under the evaluated conditions, UAV-based approaches were not efficient for sample-based estimation of tree numbers, highlighting the need for species-specific calibration, lower-altitude flights, and improved image processing strategies.

Abstract This study developed universal near-infrared (NIR) spectroscopy models for the high-throughput prediction of wood chemical composition across multiple Pinus elliottii clones. To overcome the limited generalizability of conventional full-spectrum models caused by clone-specific spectral variations and redundancy, three feature selection algorithms were evaluated for extracting robust, clone-independent spectral features correlated with cellulose and lignin content. The Monte Carlo successive projections algorithm (MC-SPA) proved most effective, constructing high-performance models using only a minimal subset of the full-spectrum wavelengths. The resulting universal models based on MC-SPA-selected features demonstrated improved predictive accuracy and generalizability across clones. This work highlights the importance of feature wavelength selection in building highly generalizable NIR calibrations and provides a practical strategy for high-throughput screening in multi-clone breeding programs.

IntroductionConiferous_to_broadleaved forest conversion reshapes soil carbon cycling in coastal sandy ecosystems, yet its regulation on component soil respiration and thermal sensitivity remains poorly quantified. To explore the regulatory effects and underlying mechanisms of such vegetation shift on soil carbon cycling in subtropical coastal sandy lands, we carried out this comparative field study.MethodsWe investigated the conversion from Pinus elliottii (coniferous forest) to Eucalyptus urophylla × E. grandis (broadleaved forest) using a paired adjacent plot design and two_year continuous in_situ observations. Key indicators including soil respiration components, litter properties, fine root biomass, microbial activity and soil microclimate were monitored.ResultsResults showed that the conversion significantly increased total soil respiration (by 25.52%), root respiration (by 62.74%), and heterotrophic respiration (by 9.01%). This promotion was driven by the coupled effects of improved litter quality (low C/N ratio and lignin content), a sharp increase in fine root biomass (by 272.5%), and enhanced microbial activity. It also notably reduced the temperature sensitivity (Q10 from 2.29 to 1.55) of soil respiration, with root respiration becoming nearly temperature_insensitive (Q10=1.25). Additionally, the explanatory power of soil temperature for respiration decreased significantly (from 76% to 37.7%), while the regulatory role of litter quality, fine root biomass, and soil microbial activity became prominent, and soil moisture did not act as a limiting factor for soil respiration throughout the study period.DiscussionThis conversion achieves a virtuous cycle of “high carbon turnover and high carbon sequestration”, clarifying the above_belowground coupling mechanism of soil carbon dynamics. Our findings thereby provide important scientific support for the optimization of coastal protection forests and the enhancement of carbon sequestration capacity in fragile coastal ecosystems.

This study evaluated ectomycorrhizal compatibility, functional effects, and the inoculum-dose response of Lactarius quieticolor and Tuber floridanum in Pinus elliottii and Pinus taeda, aiming to understand the role of fungus-host specificity in the expression of growth and physiological responses. Basidiomes of Lactarius spp. used as the inoculum source were identified through morphological and molecular analyses, confirming the identity as L. quieticolor. The symbiont L. quieticolor formed ectomycorrhizae on both Pinus species, whereas T. floridanum established an association only with P. elliottii, representing the first experimental record of this interaction. In P. elliottii, both fungi elicited integrated responses regardless of dose, with increases in growth, root biomass and electron transport rate, while L. quieticolor also increased root length, phosphorus content and modulated initial chlorophyll fluorescence. In P. taeda, effects were more limited and dose-dependent: increases in shoot nitrogen content, electron transport rate and root colonization were observed only at the highest inoculum concentrations. Multivariate analyses revealed a clear separation between control and inoculated plants even as the fungal treatments, indicating specific functional signatures. Altogether, the results demonstrate that ectomycorrhizal compatibility is not universal among congeneric Pinus species and highlight the potential of L. quieticolor and T. floridanum as functional ectomycorrhizal symbionts, with implications for seedling production and the ecology of forest systems.

ABSTRACT The expansion of agriculture in Brazil has led to an increase in waste generation and higher energy demand. This study compares the use of sawdust residues from Eucalyptus grandis W. Hill ex Maiden (EG) and Pinus elliottii Engelm. (PE), combined with residual chicken visceral oil (CVO) from the poultry slaughtering industry, for briquette production. An initial screening, a compaction and stability test, involved producing pure sawdust briquettes under loads of 2.55 to 15.29 MPa to evaluate their post-briquetting integrity. In parallel, raw materials were characterized. The stability tests revealed that EG briquettes maintained their integrity at loads from 5.10 to 15.29 MPa, whereas PE briquettes were only stable at the highest load (15.29 MPa). Consequently, EG was selected for developing composite briquettes. TGA characterization further supported this choice, showing EG has a more favorable two-stage thermal degradation, suggesting more stable combustion than PE’s single-stage profile. As expected, CVO possesses a much higher HHV (40.46 MJ/kg) than the sawdusts. While increasing CVO content boosts the briquette’s energy, a processing limit was identified: oil exudation during pressing. At the maximum tested load of 15.29 MPa, the optimal formulation was found to be 20% CVO. The resulting briquette exhibited a measured HHV of 23.61 MJ/kg, representing an energy increase of over 21% compared to the pure EG briquette.

In the context of the energy transition, there is an increasing need for research focused on low-cost feedstocks, such as lignocellulosic biomass, and on process optimization for the sustainable production of biofuels. Traditionally, processing lignocellulosic materials requires multiple stages. In this scenario, consolidated bioprocessing (CBP) emerges as a promising alternative by integrating enzyme production, hydrolysis, and fermentation into a single step. This study aimed to develop a CBP for bioethanol production using residues from oyster mushroom cultivation (Pleurotus ostreatus), composed of Pinus elliottii sawdust and soybean hulls (Glycine max). Preliminary tests were conducted to define the CBP conditions: the effects of biological (mushroom cultivation) and alkaline (sodium hydroxide) pretreatments were evaluated, and the production of cellulolytic enzymes by Trichoderma sp. was investigated in solid-state fermentation (SSF) and submerged fermentation (SmF) using the raw and pretreated residues. After selecting the optimal conditions, a 2³ experimental design was carried out to assess the influence of wheat bran supplementation, commercial enzyme addition, and co-culturing (Saccharomyces cerevisiae and Bacillus velezensis) on ethanol production. Cellulolytic enzyme production was observed in both fermentation types, with the SSF using only biologically pretreated substrate yielding the highest activity (2.04 ± 0.17 U/g). In CBP, the supplementation with commercial enzyme extracts, wheat bran addition, and co-culture showed positive effects on ethanol production, resulting in 7.07 ± 0.22 g/L, representing a 15-fold increase compared to the unenhanced process. These results highlight the potential of reusing mushroom cultivation residues for sustainable bioethanol production through CBP.Graphical

According to the enemy release hypothesis (ERH), the fitness of exotic plants and their capacity to become invasive in their area of introduction may partly be attributable to the loss of their natural enemies. Invasive species may also benefit from modifying soil attributes and thereby creating a positive soil-plant feedback. We assessed the relationship between time since the establishment of the invasive Pinus elliottii and enemy release in a montane pine-nematode-specific context within the Atlantic Forest domain, by comparing soil nematode communities/functional diversity along a virtual chronosequence of invasion. Our findings confirmed the premises of the ERH and suggest that invasion may be facilitated by a lesser nematode load on pine compared to that on native species. The impact of P. elliottii on nematode communities over time was mainly driven by changes in the trophic structure with a major depletion of phytophagous species and overall nematode richness. The findings suggest that P. elliottii after experiencing an initial reduction in natural enemy pressure in its exotic range, further changes the composition of soil organisms in its rhizosphere. This has implications for plant-soil feedbacks which, in turn, affect the dynamics of pine invasion in neotropical montane ecosystems.

Influence of fertilization, irrigation and wind on growth and wood properties of five very young South African grown Pinus species and hybrids

Leveraging close-range UAV phenotyping and GWAS for enhanced understanding of slash pine growth dynamics

Ectomycorrhizal fungi (ECMF) function as critical mediators connecting plant roots and associated microorganisms. These fungi establish intimate associations with the root systems of diverse higher plants, particularly Pinaceae species, constituting essential components of forest ecosystems. The current understanding of ECMF community structure in Pinus elliottii and its potential associations with soil characteristics remains inadequate. This investigation examined seasonal variations in rhizosphere soil physicochemical properties and fungal community dynamics between susceptible (YB) and healthy (YJ) P. elliottii using amplicon sequencing. The results demonstrated significant seasonal differences in fungal community composition between YB and YJ. Dominant ECMF genera exhibited distinct distribution patterns, with Rhizopogon predominating in YJ and Tricholoma in YB. Correlation analyses revealed strong associations between these ECMF taxa and key soil parameters (available potassium, total phosphorus, and available phosphorus), indicating substantial seasonal influences of phosphorus and potassium cycling on ECMF development. Ericoid mycorrhizal fungi displayed higher abundance in YJ samples during spring, suggesting their dual role in facilitating nutrient acquisition and enhancing host plant resilience against biotic and abiotic stresses. These findings provide novel insights into seasonal dynamics of fungal communities in P. elliottii ecosystems and offer practical implications for sustainable plantation management under global change scenarios.

Abstract Key message The study investigates how wind exposure influences wood density and microfibril angle in two Pinus taxa, revealing greater sensitivity in Pinus elliottii × caribaea and highlighting MFA as a better wind-response indicator. Abstract Wind is one of the most persistent natural forces affecting plants, driving them to adapt their properties for survival. With the projected increase in wind intensity and coverage, commercial forests face growing vulnerability. This study investigated how environmental factors, particularly wind, influence wood density and microfibril angle (MFA) in 14.5-year-old South African-grown Pinus taxa. A 2 × 2 factorial experiment was conducted with two taxa— P. elliottii × caribaea and P. radiata —under high and low wind exposure. Over nine months, solar-powered anemometers recorded wind speed in the plots. Sixteen randomly selected trees were sampled and bark-to-bark wood cores extracted from the north–south and east–west directions at 1.3 m height. Density and MFA were analyzed using SilviScan, and mixed-effects models were developed using weather variables as predictors. Pinus radiata demonstrated better growth in diameter, height, and crown length but showed no significant wind-related effects on wood properties. In contrast, P. elliottii × caribaea was more responsive to wind, with MFA significantly lower in trees from less windy plots. Pinus elliottii × caribaea exhibited distinct annual rings with wide earlywood and narrow latewood, whereas P. radiata had less defined rings with more latewood. Growth rings near the pith were indistinct in both taxa. Cardinal direction significantly influenced MFA, with the highest values in the northern direction. Weather variables notably impacted density and MFA on the northern side across treatments. This study contributes valuable insights into the effects of environmental factors on wood properties. However, growth and development during the juvenile stage remain a complex process, requiring further research to clarify the factors driving property variation in commercial forestry species.