Search Results (49)

Large-scale mining of rare earth resources has caused a series of ecological and environmental problems in mining areas, including soil structural degradation, nutrient depletion, acidification, and rare earth element (REE) accumulation. Conventional physicochemical remediation technologies are often limited by high costs, strong disturbance, and insufficient long-term stability. To compare the effects of different vegetation types on ecological restoration of ion-adsorption REE tailing soils, this study was conducted in an abandoned REE tailing area in Changfeng’ao, Ganxian District, Ganzhou City, Jiangxi Province. A small-scale field restoration experiment was established with three treatments: unrestored tailings (CK), slash pine (PE), and broadleaf paspalum (CS). Soil physicochemical properties, REE concentrations, bacterial and fungal community structures, and untargeted metabolomic profiles were comprehensively analyzed. Compared with CK, both PE and CS increased soil organic matter, alkali-hydrolyzable nitrogen, and available potassium and were associated with lower concentrations of several REEs, including Dy, Nd, Er, Y, and Yb, whereas the response of Ce differed between vegetation types. The two vegetation treatments exerted inconsistent effects on microbial communities: PE significantly increased bacterial richness and Shannon index and increased fungal richness, but decreased fungal Pielou evenness and Shannon index; in contrast, CS did not markedly enhance bacterial alpha diversity. Community composition analysis showed that vegetation treatments altered the relative abundances of dominant bacterial and fungal taxa, which were closely associated with changes in pH, soil organic matter, nitrogen, phosphorus and potassium nutrients, and REEs. Metabolomic analysis indicated that fatty acyls, organooxygen compounds, and carboxylic acids and derivatives were the major classes of differential metabolites. Pathways such as ABC transporters, nicotinate and nicotinamide metabolism, purine metabolism, and secondary metabolite biosynthesis may participate in soil metabolic reshaping under vegetation restoration. Overall, this study indicates that broadleaf paspalum and slash pine have differentiated ecological effects in REE tailing restoration and provides preliminary field evidence for vegetation recovery and soil microecological reconstruction in REE mining areas of southern Jiangxi. 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

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

Vegetation restoration has played a significant role in preventing soil erosion and enhancing soil carbon sequestration in the hilly regions of subtropical China. However, under long-term vegetation restoration, it remains unclear how soil organic carbon and nitrogen components synergistically change and whether their dynamics are consistent across different soil depths. This study investigates the soils of four major vegetation types in subtropical hilly regions: enclosed Masson pine forest (EMP), Masson pine forest (MP), slash pine forest (SP), and mixed broadleaf–conifer forest (MBC). Soil organic carbon (SOC) components, nitrogen components, and physicochemical properties were analyzed across different soil depths (0–100 cm) under these vegetation restoration types. Results showed that forest type significantly influenced SOC stability. The MBC exhibited the highest mineral-associated organic carbon (MAOC) content, indicating the highest SOC stability. Both the MBC and SP forests sequestered more iron-aluminum-bound organic carbon (FeOC) and less Ca-associated organic carbon (CaOC) compared to the other forest types. The dominance of FeOC over CaOC in these acidic soils highlights the critical role of iron-aluminum oxides in SOCSOC stabilization. Vegetation restoration significantly influenced the relationship between SOC and nitrogen components in the topsoil (0–20 cm), but this effect diminished in the subsoil (>20 cm). This study confirmed the depth-dependent impacts of long-term vegetation restoration on soil carbon stability and C/N stoichiometry in subtropical plantations. Targeted vegetation restoration strategies can improve SOC stability in subtropical plantations. Full article

This paper focuses on analysing the structural performance of fast-grown hardwood versus softwood glued laminated timber (GLT or glulam) beams with the aim to evaluate the potential structural use of the two main species planted in the country. In Uruguay, the first forest plantations date from the 1990s and are comprised mainly of Eucalyptus ssp. and Pinus spp. No one species were planted for a specific industrial purpose. However, while eucalyptus was primarily destined for the pulp industry, pine, which is now reaching its forest rotation, had no specific industrial destination. Timber construction worldwide is mainly focused on softwood species with medium and long forest rotation. The objective of the present work is, therefore, to analyse and compare the potential of eucalyptus (Eucalyptus grandis) and loblolly/slash pine (Pinus elliottii/taeda) to produce glulam beams for structural purposes. Experimental tests were made on sawn timber and GLT beams manufactured under laboratory conditions for both species. The relationship between the physical and mechanical properties of sawn timber showed that, for similar characteristic values of density (365 kg/m³ for pine and 385 kg/m³ for eucalyptus), and similar years of forest rotation (20–25 years for pine and around 20 years for eucalyptus) and growth rates, the structural yield of eucalyptus was higher compared to that of pine. The superior values of modulus of elasticity found in the hardwood species explained this result. Since there is no strength classes system for South American wood species, the European system was the basis for estimating and assigning theoretical strength classes from the visual grades of Uruguayan timbers. For sawn timber, a C14 strength class for pine and C20 for eucalyptus were assigned. Results showed that pine GLT could be assigned to a strength class GL20h, and eucalyptus glulam to GL24h and GL28h, demonstrating the potential of both species for producing glulam beams. Even though eucalyptus showed a better yield than pine, the technological process of manufacturing eucalyptus glulam was more challenging in terms of drying time and gluing than in the case of pine, which derivates in higher economic costs. Full article

This study aimed to compare and assess the genetic diversity and trends among the introduced family provenance, first-cycle superior trees breeding provenance, and improved-generation superior trees breeding provenance of Pinus elliottii using EST-SSR markers. The goal was to provide a foundation for advanced genetic improvement and sustainable utilization of P. elliottii in Jiangxi Province. A total of 417 individuals were analyzed for their genetic diversity and population structure using 19 pairs of SSR markers. The analysis identified 103 alleles across all the samples, with an average of 5.421 alleles per locus. Compared to other coniferous species, P. elliottii exhibited a moderate to high level of genetic diversity (I = 0.862, He = 0.457). Analysis of the molecular variance (AMOVA) revealed that 97.90% of the genetic variation occurred within provenances, consistent with a low genetic differentiation coefficient (Fst = 0.016 < 0.05) and high gene flow (Nm = 15.715) among provenances. In addition, analysis using STRUCTURE v. 2.3.4 software divided the 417 germplasm samples into two distinct groups, corroborating the results of the principal coordinates analysis (PCoA) and the unweighted pair group method with arithmetic (UPGMA) clustering analysis. Overall, the germplasm resources of P. elliottii exhibited rich genetic diversity, with the majority of the genetic variation occurring within provenances. For the genetic improvement of high-resin-yielding slash pines, breeding programs should prioritize populations with high genetic diversity while carefully selecting superior individuals from within those populations. These findings provide a solid foundation for breeding high-resin-yielding varieties and for future research on the sustainable utilization of these valuable resources. Full article

To explore the radial variation in wood properties of slash pine (Pinus elliottii Engelm.) during its growth process and to achieve the early prediction of these properties, our study was carried out in three slash pine harvest-age plantations in Ganzhou, Jian, and Jingdezhen, Jiangxi province of South China. Wood core samples were collected from 360 sample trees from the three plantations. SilviScan technology was utilized to acquire wood property parameters, such as tangential fiber widths (TFWs), radial fiber widths (RFWs), fiber wall thickness (FWT), fiber coarseness (FC), microfibril angle (MFA), modulus of elasticity (MOE), wood density (WD) and ring width (RD). Subsequent systematic analysis focused on the phenotypic and radial variation patterns of wood properties, aiming to establish a clear boundary between juvenile and mature wood. Based on determining the boundary between juvenile and mature wood, a regression equation was used to establish the relationship between the properties of juvenile wood and the ring ages. This relationship was then extended to the mature wood section to predict the properties of mature wood. Our results indicated significant differences in wood properties across different locations. The coefficients of variation for RD and MOE were higher than other properties, suggesting a significant potential for selective breeding. Distinct radial variation patterns in wood properties from the pith to the bark were observed. The boundary between juvenile and mature wood was reached at the age of 22. The prediction models developed for each wood property showed high accuracy, with determination coefficients exceeding 0.87. Additionally, the relative and standard errors between the measured and predicted values were kept below 10.15%, indicating robust predictability. Mature wood exhibited greater strength compared to juvenile wood. The approach of using juvenile wood properties to predict those of mature wood is validated. This method provides a feasible avenue for the early prediction of wood properties in slash pine. Full article

The southeastern United States was historically characterized by open forests featuring fire-adapted species before land-use change. We compared tree composition and densities of historical tree surveys (1802 to 1841) to contemporary tree surveys, with the application of a similarity metric, in the Coastal Plain ecological province of Mississippi, southeastern USA. We detected the boundary between historical pine and oak-pine open forests and differentiated historical and current forests. In the Coastal Plain, historical open forests converted from fire-tolerant longleaf pine (Pinus palustris) dominance, with pines comprising 88% of all trees, to loblolly (Pinus taeda) and slash (P. elliottii) pines within monocultures (45% of all trees). Wetland and successional tree species increased to 33% of all trees. Contemporary forests have greater tree densities, transitioning from closed woodlands (range of 168 to 268 trees ha⁻¹) to closed forests (336 trees ha⁻¹). In the ecotonal boundary of the northern Coastal Plain between historical pine and pine-oak woodlands, the pine component shifted over space from 88% to 34% of all trees due to a greater oak component. Fire-tolerant shortleaf pine and oak dominance converted to planted loblolly pine (52% of all trees), while successional tree species increased (20% of all trees). Historical tree densities represented woodlands (range of 144 to 204 trees ha⁻¹) but developed into closed forests (400 trees ha⁻¹). Historical Coastal Plain longleaf pine woodlands differed more from historical ecotonal oak-pine woodlands than contemporary forests differed from each other, demonstrating unique historical ecosystems and landscape-scale homogenization of ecosystems through forestation. Full article

Understory biomass plays an important role in forests, and explicit characterizations of live and dead understory vegetation are critical for wildland fuel characterization and to link understory vegetation to ecosystem processes. Current methods to accurately model understory fuel complexity in 3D rely on expensive and often inaccessible technologies. Structure-from-motion close-range photogrammetry, in which ordinary photographs or video stills are overlaid to generate point clouds, is promising as an alternative method to generate 3D models of fuels at a fraction of the cost of more traditional field surveys. In this study, we compared the performance of close-range photogrammetry with field sampling surveys to assess the utility of this alternative technique for quantifying understory fuel structure. Using a commercially available GoPro camera, we generated 3D point cloud models from video-derived image stills of 138 sampling plots across two western ponderosa pine and two southeastern slash pine sites. We directly compared structural metrics derived from the photogrammetry to those derived from field sampling, then evaluated predictive models of biomass calibrated by means of destructive sampling. Photogrammetry-derived measures of occupied volume and fuel height showed strong agreements with field sampling (Pearson’s R = 0.81 and 0.86, respectively). While we found weak relationships between photogrammetry metrics and biomass 0 to 10 cm in height, occupied volume and a novel metric to characterize the vertical profile of vegetation produced the strongest relationships with biomass above the litter layer (i.e., >10 cm) across different fuel types (R² = 0.55–0.76). The application of this technique has the potential to provide managers with an accessible option for inexpensive data collection and can lay the groundwork for the rapid collection of input datasets to train landscape-scale fuel models. Full article

While many tree species occur across the Coastal Plain of the southeastern United States, longleaf pine (Pinus palustris C. Lawson) savannas and woodlands once dominated this region. To quantify longleaf pine’s past primacy and trends in the Coastal Plain, we combined seven studies consisting of 255,000 trees from land surveys, conducted between 1810 and 1860 with other descriptions of historical forests, including change to the present day. Our synthesis found support that Pinus palustris predominantly constituted 77% of historical Coastal Plain trees and upland oaks (Quercus) contributed another 8%. While Pinus still dominates these forests today (58% of all trees), most are now either planted loblolly (Pinus taeda L.) or slash (Pinus elliottii Engelm.) pines. Water oak (Quercus nigra L.), live oak (Quercus virginiana Mill.), sweetgum (Liquidambar styraciflua L.), and red maple (Acer rubrum L.) have increased their proportions compared to historical surveys; both longleaf pine and upland oaks have declined to ≤5% of all trees. Our work also supports previous estimates that longleaf pine originally dominated over 25–30 million ha of Coastal Plain forests. As late as the early 1900s, longleaf pine may still have covered 20 million ha, but declined to 7.1 million ha by 1935 and dropped to 4.9 million ha by 1955. Longleaf pine’s regression continued into the mid-1990s, reaching a low of about 1.3 million ha; since then, restoration efforts have produced a modest recovery to 2.3 million ha. Two centuries of overcutting, land clearing, turpentining for chemicals, fire exclusion followed by forest densification by fire-sensitive species, and other silvicultural influences, including widespread loblolly and slash pine plantations, have greatly diminished the Coastal Plain’s once extensive open longleaf pine forests. Full article

Phosphorus (P) fertilizer is commonly used in subtropical plantations to augment nutrients including carbon (C), nitrogen (N), and P to maintain plants engaged in metabolism. Stoichiometric homeostasis reflects the adaptation of plants to various environments (including P fertilizer supply rates). It is thus of great significance to understand C:N:P stoichiometry in the plant–litter–soil system under P addition and the stoichiometric homeostasis of plant tissues for the P fertilization management of slash pine (Pinus elliottii Engelm) plantations. In subtropical China, we measured the C, N, and P contents in root, branch, needle, litter, and soil in slash pine plantations fertilized with four treatments, P1 (25 kg P ha¹ yr¹), P2 (50 kg P ha¹ yr¹), P3 (100 kg P ha¹ yr¹), and a control (CK), and calculated the stoichiometric homeostasis of plant tissues. The results show that P3 treatment increased the C, N, and P contents of the needle. P2 and P3 treatments increased the P content of the litter and the N:P ratio of the root while decreasing the C:N ratio of the root. P addition treatments increased C and P element accumulation in soil but had no effect on soil stoichiometry. The nutrient contents of needle and branch were higher than those of root and litter, indicating that slash pine was more inclined to allocate nutrients to the aboveground tissues. The stoichiometric homeostasis of C, N, and P among plant tissues was graded as follows: root > branch > needle. The needle’s nutritional homeostasis was C > N > P, with 1/H values of 0.08, 0.34, and 0.74, respectively. These findings demonstrate that during P addition, the C, N, and P stoichiometric homeostasis varied among plant tissues and element types. In conclusion, P application altered nutrient distribution in the plant–litter–soil system, alleviating P restriction in slash pine forests in southern China. P addition levels should be finely adjusted in the future for longer-term observation trials, and the trade-off between P addition rates and economic and ecological advantages should be properly examined. Full article

Ecological stoichiometry plays important roles in understanding the nutrient constraints on tree growth and development, as well in maintaining ecosystem services in forests, yet the characteristics of carbon:nitrogen:phosphorous (C:N:P) stoichiometry in forests under karst environment have not been sufficiently evaluated. In this study, concentration, distribution, stocks of Nitrogen (N) and Phosphorous (P), and ecological stoichiometry were studied in three common forest types: Masson pine natural forests (MPNF), Masson pine plantation forests (MPPF), and Slash pine plantation forests (SPPF) in a karst region of southwestern China. Results showed that N concentrations were higher in overstory than in understory and litter in the studied forests. However, P concentration was relatively low in overstory component of the forested ecosystems. Meanwhile, the N and P concentrations were higher in SPPF in the stem and litter, while these contents were higher in MPPF and MPNP in the overstory and understory. The N and P stocks ranged from 5.7–6.2 t ha⁻¹, and 0.5–0.6 t ha⁻¹ in the examined forests. The ecological stoichiometry of C:N:P in the three forest types was similar in litter (46–49:2:1), and relatively steady in soil (250–320:13–16:1) and tree leaf (100–200:14–20:1). Soil P status was the primary limiting factor in affecting tree growth in MPPF and SPPF (N:P ratio > 16), while both N and P conditions were the main restrictive factors in MPNP (N:P ratio = 15) in the study area. Our study provides scientific references and useful datasets of C:N:P stoichiometry for sustainable management of forest ecosystems in karst regions. Full article

Phytoremediation using woody plants can effectively reduce heavy metal (HM) concentrations in soils. However, the remediation capacity of woody plants depends greatly on plant species and soil environmental conditions. In order to evaluate the HM remediation potential of woody plants from different tailing areas, the HM accumulation characteristics of roots, shoots, and leaves of 12 dominant native woody plants growing in iron and lead-zinc tailing areas were analyzed. The results showed that the concentrations of Cd, As, Ni, Mn, and Cr in most plants in the two tailing areas exceeded the level of normal plants. The distribution of different elements in plants was generally as follows: root > leaf > shoot for Pb and As; root > shoot > leaf for Cr; and leaf > shoot > root for Zn, Ni, and Mn. The distribution of Cu and Cd in plants varied with the type of HM pollution in the two tailing areas. There were significant (p < 0.05) negative correlations between available phosphorus in the soil and Pb, Cd, and Zn in the plant roots when the soil was heavily polluted with Pb, Cd, and As; similarly, there were significant (p < 0.01) negative correlations between readily available potassium in the soil and Pb, Zn, and Ni in plant roots. Based on the higher than average concentration of HMs in plants, and higher bioconcentration factors and translocation factors, some plants were considered woody plant species with phytoremediation. Slash pine (Pinus elliottii) and indian azalea (Rhododendron simsii) had strong enrichment and translocation abilities for Cd, oriental white oak (Quercus glauca) and beautiful sweetgum (Liquidambar formosana) for Mn and paulownia (Paulownia fortunei) for Zn. The plants listed above can be used as potential species for phytoremediation in iron and lead-zinc tailing areas. Full article

Fusarium circinatum causes pine pitch canker (PPC) disease and associated symptoms such as resinous lesions, mechanical weakness, and crown dieback that may lead to mortality in Pinus and Pseudotsuga spp. There are no ameliorative techniques available for the disease, and the genetic resistance among populations to support commercial plantation deployment has not been well characterized. In this study, we characterize the genetic control of PPC disease tolerance (and/or resistance) and predict the tolerance of families in existing breeding populations: open-pollinated (OP) half-sib and control-pollinated full-sib (FS) slash pine (Pinus elliottii var. elliottii Engelm.), OP loblolly pine (Pinus taeda L.), and advanced-generation OP hybrid slash × P. caribaea (Pinus elliottii var. elliottii Engelm. × Pinus caribaea var. bahamensis, caribaea, and hondurensis) using F. circinatum isolates obtained from three locations in Georgia and FL, USA. We describe a new experimental design that improves the accuracy of breeding value predictions, provides more precise genetic parameter estimates, and facilitates comparisons within and among taxa as well as comparisons among isolates. We found strong evidence for genetic control of the ratio of stem damage by F. circinatum, especially in slash pine and slash × P. caribaea hybrids. Loblolly and slash × P. caribaea hybrids exhibited less damage than slash pine. We observed a spectrum of virulence among F. circinatum isolate sources, which were not equally virulent in different pine taxa. Full article