Search Results (77)

The development of low-cost and sustainable adsorbents for carbon dioxide (CO₂) capture has gained increasing attention as a strategy to mitigate greenhouse gas emissions. In this study, activated biochars produced from babassu, elephant grass, and Pinus elliottii were evaluated as CO₂ adsorbents after different activation treatments. The biochars were produced by slow pyrolysis at 400 °C and subsequently modified using three activation routes: steam activation, chemical activation with KOH, and KOH activation followed by acid washing. The materials were characterized by proximate analysis, specific surface area measurements, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, and CO₂ adsorption tests. Steam activation produced the highest specific surface areas, reaching 1270.53, 1027.28, and 907.87 m² g⁻¹ for babassu, elephant grass and Pinus, respectively. Despite the superior textural properties achieved through steam activation, the highest CO₂ adsorption capacities were obtained for the samples subjected to chemical activation followed by acid washing. These results indicate that adsorption performance is governed not only by the development of surface area but also by pore accessibility and the surface chemistry of the adsorbent. Maximum adsorption capacities of 82.78, 81.19, and 85.24 mg g⁻¹ were obtained for ACKAW B, ACKAW CE, and ACKAW P, respectively. Adsorption–desorption cycling experiments demonstrated regenerability and stable performance over repeated cycles. The results indicate that KOH activation followed by acid washing is an effective strategy for producing high-performance biochar-based adsorbents for CO₂ capture. Full article

Somatic embryo-derived plantlets of pines often fail to survive acclimatization, which limits commercial micropropagation. Conventional hardening methods do not correct the physiological weaknesses of in vitro plantlets, especially the lack of beneficial microbes. Here we developed a practical protocol for resistant Pinus elliottii. First, we used an optimized maturation protocol (three sequential ABA pre-treatments) and glucose for germination. Substrate screening showed that a peat:vermiculite:perlite mixture (3:1:1) gave the highest survival (98.9%). Then, before transplantation, we introduced a key bio-enhancement step: in vitro inoculation with the ectomycorrhizal fungus Pisolithus orientalis cfcc7668. This treatment achieved a mycorrhization rate of 97.7% and transformed root morphology from thin, sparsely branched roots to a coralloid, dichotomously branched system with a well-developed Hartig net. As a result, mycorrhizal plantlets had 100% transplant survival at 30 days and remained above 94% over 360 days, whereas non-inoculated controls dropped to 95.6% at 30 days and further declined to about 73% after three months. Pre-establishing ectomycorrhizal symbiosis effectively restores a key root function missing in in vitro plantlets. Our integrated procedure provides a practical method for clonal propagation of conifers. Full article

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. Full article

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. Full article

Oleoresin from Pinus spp. consists of turpentine and rosin, whose compositional variability demands reliable analytical methods for quality control and industrial processing. This study provides three rapid methods for qualitative and quantitative analyses of oleoresin, turpentine, and rosin by gas chromatography coupled with mass spectrometry (GC-MS) using a single DB-1 column and matrix-specific temperature programs. Oleoresin and rosin were first derivatized using diazomethane, and compounds were identified by elution order, fragmentation patterns, and reference mass spectra. Quantification employed external calibration with α-pinene and abietic acid as representative standards. In P. pinaster oleoresin, the main terpenic compounds were α-pinene (6.67 ± 1.08%), longifolene (2.45 ± 0.20%), and β-caryophyllene (1.71 ± 0.15%), while levopimaric (33.75 ± 2.70%), neoabietic (13.97 ± 1.70%), and abietic acids (12.60 ± 2.90%) predominated among resin acids. P. elliottii rosin contained mainly abietic (45.99 ± 4.82%), isopimaric (16.95 ± 2.55%), and palustric acids (9.74 ± 1.20%), and its turpentine comprised mainly α-pinene (34.16 ± 2.45%) and β-pinene (30.03 ± 1.20%). This unified GC–MS framework, supported by representative calibration standards, enables identification of >95% of compounds in pine matrices. Furthermore, once compound identification has been established through GC-MS, GC coupled with flame ionization detector (GC-FID) can be employed for routine quantitative analysis. Full article

Understanding the influence of tree species and their intrinsic traits on biochar yield and carbon retention is essential for optimizing the conversion of biomass to biochar in carbon-negative systems. While it is well-established that pyrolysis temperature and broad feedstock categories significantly affect biochar properties, the extent of species-level variation within woody biomass under standardized pyrolysis conditions remains insufficiently quantified. Here, we synthesized biochar from seven common subtropical tree species at 600 °C under oxygen-limited smoldering conditions and quantified three key indices: biochar yield (Y), carbon recovery efficiency (ηC), and carbon enrichment factor (EC). We further examined the relationships of these indices with feedstock characteristics (initial carbon content, wood density) and functional group identity (conifer vs. broadleaf). Analysis of variance revealed significant interspecific differences in ηC but weaker effects on Y, indicating that species identity primarily governs carbon retention rather than total mass yield. Broadleaf species (Liquidambar formosana, Castanea mollissima) exhibited consistently higher ηC and EC than conifers (Pinus massoniana, P. elliottii), reflecting higher lignin content and wood density that favor aromatic char formation. Principal component and cluster analyses clearly separated coniferous and broadleaf taxa, accounting for over 80% of total variance in carbon-related traits. Regression models showed that feedstock carbon content, biochar carbon content, and wood density together explained 15.5% of the variance in ηC, with feedstock carbon content exerting a significant negative effect, whereas wood density correlated positively with carbon retention. These findings demonstrate that tree species and their functional traits jointly determine carbon fixation efficiency during smoldering. High initial carbon content alone does not guarantee enhanced carbon recovery; instead, wood density and lignin-derived structural stability dominate retention outcomes. Our results underscore the need for trait-based feedstock selection to improve biochar quality and carbon sequestration potential, and provide a mechanistic framework linking species identity, functional traits, and carbon stabilization in biochar production. Full article

Post-harvest forest residue management and liming practices can significantly affect soil quality. This study evaluated the impacts of burnt pine harvest residues and lime application methods (surface-applied vs. incorporated) on the chemical and physical properties of a Dystric Cambisol in Southern Brazil. Soil samples were collected at two depths (0–10 cm and 10–20 cm) and analyzed for pH, exchangeable acidity, organic carbon, cation exchange capacity, macroporosity, microporosity, and bulk density. The results showed that changes were more pronounced in the 0–10 cm layer and mainly affected chemical attributes. Incorporated lime increased pH from 4.7 to 5.1, increased base saturation from 17% to 36%, and reduced Al saturation from 45% to 13% in the 0–10 cm layer. Burnt residues alone did not significantly alter soil properties, whereas lime incorporation led to improved chemical conditions and enhanced soil structure, especially in the surface layer. The treatments that maintained pine residues on the surface favored biological processes in the topsoil, while the burning of these residues had variable impacts on soil structure and nutrient availability. These findings highlight the importance of incorporating lime to optimize soil rehabilitation following pine harvesting in subtropical forest systems. Full article

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. Full article

Grafting constitutes a crucial approach for the preservation of pine clones. Slash pine is commonly used as the rootstock for grafting Masson pine scions in Guangxi. In this context, the fresh oleoresin samples of Masson pine, slash pine, and grafted pine (with Masson pine as scion and slash pine as rootstock) were analyzed by gas chromatography–mass spectrometry and gas chromatography, and the key chemical components (α-pinene, β-pinene, longifolene, and isopimaric acid) that can quickly and accurately distinguish the oleoresin of Masson pine and slash pine were found and identified. According to the changes in the relative content of key compounds of oleoresin in scion and rootstock, it was found that the oleoresin of rootstock and scion could interact. Further research showed that the mutual influence of oleoresin between rootstock and scion was persistent, and the influence of rootstock on oleoresin at the scion was affected by height. However, the height effect included a large individual differences, which were not significantly related to the grafting height, tree height, diameter at breast height, etc., but may have been related to the differences in synthesis speed of oleoresin between rootstocks and scions. This work reveals the possible mechanism of mutual influence and secretion of oleoresin in grafted pine trees, laying a foundation for the study of the characteristics of oleoresin from pines grafted by different types, with great significance for the breeding of pine with high yield of oleoresin, and the production and application of special compounds containing oleoresin. Full article

To investigate the responses and mechanisms of slash pine under low orthophosphate (Pi) stress and to identify Pi-efficient lines, we analyzed 12 indices related to biomass, root traits, and tissue Pi concentration across 13 slash pine lines subjected to varying Pi treatments. The composite assessment value of low-phosphorus tolerance (D) was calculated by evaluating these 12 response indicators through principal component analysis, in conjunction with the fuzzy membership function method. Nine low-phosphorus tolerance factors (LPTFs)—including above-ground fresh weight (0.69), below-ground fresh weight (0.52), total root length (0.56), root surface area (0.63), root volume (0.67), above-ground Pi concentration (0.78), below-ground Pi concentration (0.52), bioconcentration factor (0.77), and P utilization efficiency (−0.76)—showed significant correlations with D (p < 0.05). Utilizing these nine LPTFs, cluster analysis classified the 13 lines into the following three groups according to their low-phosphorus (P) tolerance: high-P-efficient, medium-P-efficient, and low-P-efficient lines. Under low Pi and Pi-deficiency treatments, line 27 was identified as a high-P-efficient line, while lines 1, 6, and 9 were classified as low-P-efficient lines. Notably, eight genes (SPX1, SPX3, SPX4, PHT1;1, PAP23, SQD1, SQD2, NPC4) and five genes (SPX1, SPX3, SPX4, PAP23, SQD1) were significantly up-regulated in the roots and leaves of both line 27 and line 9 under low-phosphorus stress, respectively. However, the high-P-efficient line 27 exhibited a stronger regulatory capacity with a higher expression of two genes (SPX4, SQD2) in the roots and nine genes (SPX1, SPX3, SPX4, PHT1;1, PAP10, PAP23, SQD1, SQD2, NPC4) in the leaves under low Pi stress. These findings reveal differential responses to low Pi stress among slash pine lines, with line 27 displaying superior low-P tolerance, enabling better adaptation to low Pi environments and the maintenance of normal growth, development, and physiological activities. Full article

Pinus elliottii, a key economic conifer in southern China, requires efficient propagation methods to meet demand for elite germplasm in resin and timber production. While somatic embryogenesis-based plant regeneration has been successfully achieved in Pinus elliottii, large-scale production remains challenging. Our results demonstrate that the genotype of Pinus elliottii significantly influences the induction rate of embryogenic callus. During somatic embryo maturation, the liquid–solid induction method increased the number of mature embryos by 25.85 times. Maturation efficiency was further enhanced by a 3-week pretreatment followed by the application of 9 mg/L ABA, 0.5 mg/L PSK, and 6 mg/L COS. Additionally, the incorporation of activated carbon significantly promoted both the maturation and germination of somatic embryos. In the somatic embryo maturation stage, 1 g/L activated carbon induced 288.67 mature embryos per gram of embryogenic callus, resulting in a total of 1452 embryos. During germination, the application of 4 g/L activated carbon achieved a germination rate of 63%, and the survival rate of somatic embryo-derived seedlings reached 85%. This study not only identifies the optimal conditions for somatic embryogenesis in Pinus elliottii but also establishes an efficient protocol for somatic embryo maturation induction, providing a crucial scientific foundation for the rapid propagation and seedling production of Pinus elliottii. Full article

The nitrogen (N) and phosphorus (P) additions were commonly used to improve plantation quality. However, the balance between nutrient uptake in the underground part and nutrient utilization in the aboveground part of Pinus elliottii (Slash pine) plantation in subtropical regions after N and P addition is still unclear. We conducted the experiment using a randomized complete block design with four treatments: N (50 kg N ha⁻² yr⁻¹, P (100 kg P ha⁻² yr⁻¹), NP (N + P), and a control (CK). Nutrient transport dynamics of underground (rhizosphere soil and roots) and aboveground (twigs and needles) parts of a 10-year-old Pinus elliottii plantations were evaluated. The trial was maintained for three consecutive growing seasons. The results showed that N and P additions significantly increased the N, P, and potassium (K) contents of soils and plant tissues in subtropical slash pine plantation forests, and showed a significant and gradual increase in interannual variations over the observation period (except for TN in soils, which increased first and then decreased). In terms of nutrient transport and reabsorption efficiency, N addition promoted the transport of elemental P from the translocating root system to the twigs, whereas P addition inhibited this process. P addition significantly increased the nitrogen reabsorption efficiency (NRE) of the needles, but decreased the phosphorus reabsorption efficiency (PRE), showing an element-specific response to the nutrient reabsorption process. Structural equation modeling further revealed that N or P addition had direct positive effects on soil N, P, and K content (path coefficients r: 0.54, 0.71, 0.41). N addition indirectly negatively affected N resorption efficiency (NRE) and K resorption efficiency (KRE) (r: −0.62, −0.51) but positively affected PRE (r: 0.44). Conversely, P addition had an indirect negative effect on PRE (r: −0.59). These results reveal that in subtropical regions, slash pine plantations adapt to N or/and P addition by adjusting nutrient absorption, transport, and resorption efficiency. This provided new insights into nutrient transport and distribution strategies in underground and aboveground parts of plants under N or/and P additions. Full article

The present study aims to evaluate the mechanical properties, colorimetric characteristics, and decay resistance of Pinus elliottii woods treated with oxides synthesized via green chemistry. For this purpose, an aqueous extract from Eucalyptus dunnii leaves was used to synthesize particles based on copper- and zinc-based oxides, as well as a binary oxide system (CuO/ZnO). Sodium polyacrylate was employed as a dispersant, impregnating the oxides into the wood through a horizontal autoclave using a modified Bethell process, assisted by a compressor, applying a pressure of 0.8 MPa for 30 min. The exposure to weathering aging did not significantly alter the mechanical properties of the samples, but it caused the leaching of particles from the treated wood surface, as shown by colorimetric results. Regarding the decay resistance, the copper-based oxide proved to be the most effective treatment against Trametes versicolor (a white-rot fungus), reducing mass loss down to 1.2%. The CuO/ZnO formulation reduced the mass loss caused by Gloeophyllum trabeum to 1.1%, while the zinc oxide showed minimal efficacy. Thus, oxides synthesized via green chemistry using aqueous leaf extracts and mild thermal conditions for synthesis and calcination proved effective in enhancing the wood resistance against biotic deterioration agents. Full article

Plant nitrogen (N), phosphorus (P), and potassium (K) concentrations and ratios serve as critical indicators of nutrient constraints in coastal ecosystems. However, the response of leaf–soil N-P-K stoichiometry in tropical coastal shelterbelt forests to seasonal rainfall variations remains poorly understood. This study measured total N, P, and K contents in leaves and soils of three typical tropical coastal shelterbelt forests in Wenchang, China—Casuarina equisetifolia L., Cocos nucifera L., and Pinus elliottii × caribaea—during August 2022 (wet season) and February 2023 (dry season). Key findings are as follows: (1) All three forests exhibited low N-P-K contents in both leaves and soils, with significant stand-specific variations. Soil N:P ratios were consistently below 14, indicating chronic N limitation for plant growth. (2) Wet seasons significantly altered leaf–soil N-P-K contents and stoichiometric ratios. (3) Leaf and soil stoichiometric traits exhibited strong correlations, but these relationships diverged under seasonal transitions. (4) Shifts from wet to dry seasons increased the sensitivity of N-P-K stoichiometric homeostasis, reflecting weakened nutrient buffering capacity. This study reveals stand-specific nutrient cycling patterns in tropical coastal shelterbelts, with seasonal rainfall modulating soil–leaf nutrient coupling and stoichiometric stability. These findings provide a theoretical basis for optimizing nutrient management and species configuration in tropical coastal ecosystems under climate variability. Full article

Coastal forests are highly vulnerable to disturbances from tropical cyclones (TCs), yet the long-term impacts of storm surges on tree growth remain understudied. This study examines the relationship between TC-induced storm surges and annual tree-ring growth in Pinus elliottii at three coastal sites along the northern Gulf of Mexico. Using dendrochronological methods, we analyzed total ring width, earlywood, and latewood growth patterns to assess suppressions in response to past TC activity. Our results indicate that storm surge events consistently cause growth suppression, with recovery periods averaging two to three years. However, suppression patterns vary by site, with trees in more protected locations displaying stronger correlations with TC storm surge events, while those in chronically stressed environments exhibit frequent growth limitations independent of TCs. For example, only 38% of suppression events at the unprotected Gulf State Park correspond with TC storm surge events, and this increases to 67% at the protected Weeks Bay NERR site. Additionally, latewood ring width corresponds with TC storm surge events more than total or earlywood ring width. These findings highlight the complexity of TC impacts on coastal tree growth, emphasizing the importance of site-specific factors such as topographic position and hydrological conditions. Understanding these interactions is critical for improving paleotempestology reconstructions and informing forest management strategies in coastal environments facing increasing TC activity due to climate change. Full article