Search Results (112)

Soil organic carbon (SOC) is the largest reservoir of terrestrial organic carbon and plays a pivotal role in regulating global climate dynamics. And there are some differences in SOC stocks under different forest stand types. But it is unclear whether this phenomenon is related to SOC stability, especially stable components of SOC. Therefore, coniferous (Pinus tabuliformis), broad-leaved (Quercus aliena), and mixed forests were selected to explore the distributions and chemical structures of SOC components, as well as SOC stabilization mechanisms. Higher SOC contents but lower stability were observed under Quercus aliena forests. Contents of SOC and its components were lowest under Pinus tabuliformis forests. Yet the highest relative abundances of alkyl and aromatic carbon in mineral-associated organic carbon (MAOC) were found at 10–40 cm soil layers, with the highest MAOC/SOC. In contrast, MAOC/SOC was highest under mixed forests at 0–10 cm layer. Total nitrogen (TN), lignin, and silt contents were identified as key drivers of SOC stability. These findings indicated that mixed forest contributes more to enhancing SOC stability in topsoil, whereas coniferous forest promotes greater stability in subsurface layers. These results suggested that the functional complementarity among forest stand types may enhance carbon sequestration and promote the sustainability of forest management. Full article

In this study, we focused on four major coniferous species in the eastern part of Inner Mongolia, namely Larix gmelinii var. principis-rupprechtii (Mayr) Pilg., Larix gmelinii (Rupr.) Kuzen., Pinus tabuliformis Carrière and Pinus sylvestris var. mongolica Litv. and carried out a systematic study on their ectomycorrhiae (EM) fungi. The present study was based on high-throughput sequencing. Based on the high-throughput sequencing data, analyzed by bioinformatics and statistical methods, the results showed that (1) a total of 150 operational taxonomic units (OTUs) were obtained, which belonged to 26 evolutionary branches of Basidiomycota and Ascomycota, respectively. Among them, Tricholoma, Tomentella-thelephora, Suillus-rhizopogon, Wilcoxina, Piloderma, Pustularia, Hygrophorus, Sebacina and Amphinema-tylospora are the EM fungi shared by four conifer species. (2) The species diversity and community composition of EM fungi differed significantly among tree species and sample plots, while soil total nitrogen (N) content and nitrogen/phosphorus (N/P) ratio were the main factors affecting community structure. (3) The Neutral Community Model (NCM) and β-Nearest Taxon Index (β-NTI) showed that stochastic processes dominated the construction of EM fungal communities. The results of this study revealed the geographical distribution pattern and maintenance mechanisms of EM fungal communities of four coniferous species in the eastern part of Inner Mongolia, which provides a scientific basis for the restoration practice of disturbed ecosystems and the sustainable development of the regional economy. Full article

Spring droughts, increasingly coinciding with canopy shade, interactively stress the growth of urban tree species and are poorly understood in Beijing. Three-year-old saplings of Pinus tabuliformis and Robinia pseudoacacia were subjected to comparative analysis under four drought–shade sequences, with a full-light, well-watered treatment serving as the control. During two periods encompassing the drought to wilting point and subsequent rewatering, we assessed leaf morphology, water status, photosynthetic gas exchange, and chlorophyll fluorescence. Both species exhibited losses in leaf water and carbon assimilation under drought, yet their adaptive strategies substantially differed. P. tabuliformis conserved water through the stable leaf anatomy and conservative stomatal control. In particular, P. tabuliformis under full-light and drought conditions decreased their specific leaf area (SLA) by 23%, as well as showing reductions in stomatal conductance (G_s) and transpiration rate (T_r) along with the drought duration (p < 0.01). As the duration of post-drought rewatering increased, the reductions in the net photosynthetic rates (P_n) of P. tabulaeformis showed that the shade condition intensified its photosynthetic limitation and slowed recovery after drought. Under low-light drought, R. pseudoacacia exhibited a 52% increase in SLA and a 77% decline in G_s; the latter was markedly smaller than the reduction observed under full-light drought. After rewatering, G_s displayed an overcompensation response. The rise in specific leaf area and the greater flexibility of stomatal regulation partly offset the adverse effects of drought. Nevertheless, post-drought P_n recovered to only 40%, significantly lower than the 61% recovery under full-light drought. Moreover, the negative correlation between SLA and P_n became significantly stronger, indicating that the “after-effects” of shade–drought hindered photosynthetic recovery once the stress was relieved. Drought duration eroded the phenotypic performance in both species, while the light environment during drought and subsequent rehydration determined the time trajectory and completeness of recovery. These results validate a trade-off between shade mitigation and drought legacy, and guide species selection: plant shade-tolerant R. pseudoacacia in light-limited urban pockets and reserve sun-dependent P. tabuliformis for open, high-light sites to enhance drought resilience of Beijing’s urban forests. Full article

Chinese pine, Pinus tabuliformis, is one of the most important garden plants in northern China, and the planting of this species is of great significance for the improvement of the ecological environment. In this study, different fungi were isolated and purified from diseased Pinus tabuliformis samples collected in Xi’an city, Shaanxi Province. Of these fungal isolates, only one (isolate AP-3) was pathogenic to the healthy host plant. The pathogenic isolate was identified as Fusarium acuminatum by morphological characteristics and ITS and TEF-1α sequence analyses. The optimal growth conditions for this isolate were further analyzed as follows: Optimal temperature of 25 °C, pH of 11, soluble starch and sodium nitrate as the most preferred carbon and nitrogen sources, respectively. By combining Oxford Nanopore Technologies (ONT) long-read sequencing with Illumina short-read sequencing technologies, we obtained a 41.50 Mb genome assembly for AP-3, with 47.97% GC content and 3.04% repeats. This consisted of 14 contigs with an N50 of 4.64 Mb and a maximum length of 6.45 Mb. The BUSCO completeness of the genome assembly was 98.94% at the fungal level and 97.83% at the Ascomycota level. The genome assembly contained 13,408 protein-coding genes, including 421 carbohydrate-active enzymes (CAZys), 120 cytochrome P450 enzymes (CYPs), 3185 pathogen-host interaction (PHI) genes, and 694 candidate secreted proteins. To our knowledge, this is the first report of F. acuminatum causing needle blight of P. tabuliformis. This study not only uncovered the pathogen responsible for needle blight of P. tabuliformis, but also provided a systematic analysis of its biological characteristics. These findings provide an important theoretical basis for disease control in P. tabuliformis and pave the way for further research into the fungal pathogenicity mechanisms and management strategies. Full article

A systematic examination of leaf functional traits, environmental determinants, and adaptive regulation strategies in old Pinus tabuliformis was conducted in the Loess Plateau region. During the peak growth period (July) of P. tabuliformis in 2023 and 2024, integrating phylogenetic comparative methods with environmental gradient analysis, we quantified 28 functional traits (7 morphological, 8 anatomical, 5 chemical, and 8 physiological traits) of old P. tabuliformis. The result shows significant spatial differentiation in leaf chemical and physiological traits, demonstrating exceptional environmental plasticity. Old trees in the Huanglong area of central China tend to be of the resource acquisition type, while the proportion of the Stress-tolerators strategy (S strategy) is higher in the Taibai (S% = 92.32). The combined effect of environmental factors is the main driving factor for the diversity of leaf functional traits (33.56%), while the independent effect of phylogenetic accounts for only 8.91%. And regression modeling identified several traits, such as Malondialdehyde (MDA), Peroxidase (POD), and Superoxide dismutase (SOD), as sensitive indicators of geographical and climatic adaptation. In conclusion, this study elucidates drought adaptation mechanisms in old P. tabuliformis through leaf functional trait analysis, establishing a scientific framework for conserving old trees in Loess Plateau under climate change. Full article

Anthropogenic revegetation allows effective and timely soil development in mine restoration areas. The evaluation of soil quality is one of the most important criteria for measuring reclamation effectiveness, providing scientific reference for the subsequent management of ecological restoration projects. The aim of this research was to further investigate the influence of revegetation on mine-reclaimed soils in a semi-arid region. Thus, a coal-gangue dump within the afforestation chronosequence of 1 and 19 years in Shanxi Province, China, was selected as the study area. We assessed the physicochemical properties and nutrient stock of topsoils under four revegetation species, i.e., Pinus tabuliformis (PT), Medicago sativa (MS), Styphnolobium japonicum (SJ), and Robinia pseudoacacia ‘Idaho’ (RP). A two-way ANOVA revealed that reclamation age significantly affected SOC, TN, EC, moisture, and BD (p < 0.05), while the interaction effects of revegetation type and age were also significant for TN and moisture. In addition, SOC and TN stocks at 0–30 cm topsoil at the RP site performed the best among 19-year reclaimed sites, with an accumulation of 62.09 t ha⁻¹ and 4.23 t ha⁻¹, respectively. After one year of restoration, the MS site showed the highest level of SOC and TN accumulation, which increased by 186.8% and 88.5%, respectively, compared to bare soil in the 0–30 cm interval, but exhibited declining stocks during the 19-year restoration, possibly due to species invasion and water stress. In addition, an integrated soil quality index (ISQI) and the partial least squares structural equation model (PLS-SEM) were used to estimate comprehensive soil quality along with the interrelationship among influencing factors. The reclaimed sites with an ISQI value > 0 were 19-RP (3.906) and 19-SJ (0.165). In conclusion, the restoration effect of the PR site after 19 years of remediation was the most pronounced, with soil quality approaching that of the undisturbed site, especially in terms of soil carbon and nitrogen accumulation. These findings clearly revealed the soil dynamics after afforestation, further providing a scientific basis for choosing mining reclamation species in the semi-arid regions. Full article

Negative air ions (NAIs) can purify the atmosphere and maintain human health. In this study, we selected six tree species, Pinus tabuliformis, Pinus bungeana, Acer truncatum, Sophora japonica, Koelreuteria paniculata, Quercus variabilis, Robinia pseudoacacia, and Populus tomentosa, and we established for the first time five “capacity indicators” to characterize and judge the capacity of plants to release negative ions: they comprised the release contribution rate L, release coefficient n, release rate s, instantaneous current number v, and total level of release Z. These indicators were used to assess the ability of the plants to release NAIs by themselves. The results showed the following. (1) The daily variations in L and n show “W” and “concave” shapes, respectively, and the contribution capacity at night is significantly higher than that during the day. The diurnal variations in s, v, and Z all showed a “bimodal” pattern. The NAI release rate and release level of each tree species during the day were significantly higher than those at night. (2) The trees released the most NAIs during the day at approximately 10:00, while Robinia pseudoacacia and Populus tomentosa peaked with a 2 h lag (12:00). The NAI release capacity of each tree species was the worst at 13:00. (3) During the growing season, the self-contribution effects L and n of the plants were the strongest in May. The release rates and release levels s, v, and Z were the lowest in August. The coniferous plants released NAIs at the fastest rate in September and broad-leaved plants in July, with the highest release levels. In this study, the plants released the most NAIs from 10:00 a.m. to 11:00 a.m., which is the best time to travel. Quercus variabilis was preferentially recommended in the pairing of species of tree with the quickest NAI release and the highest total number released, followed by Koelreuteria paniculata and Sophora japonica. Full article

Microbial functional genes serve as the core genetic foundation driving microbial ecological functions; however, its microbial functional gene composition across varied habitats and its ecological adaptation interplay with plants remain understudied. In this study, we investigated the P. tabuliformis rhizosphere microbial functional genes which are related to N and P cycles across ridge and slope habitats between different elevational gradients, analyzed their composition and abundance, and analyzed their responses to environmental factors. Results showed that slope habitats had a significantly greater abundance of N and P cycling functional genes compared to those of ridge counterparts (p < 0.05). Specifically, slope environments showed an enhanced gene abundance associated with denitrification, nitrogen fixation, nitrification, assimilatory/dissimilatory nitrate reduction, and nitrogen transport processes, along with the superior expression of genes related to inorganic/organic phosphorus metabolism, phosphorus transport, and regulatory gene expression. These nutrient cycling gene levels were positively correlated with soil nutrient availability. Our findings revealed distinct ecological strategies: Ridge communities employ resource-conservative tactics, minimizing microbial investments to endure nutrient scarcity, whereas slope populations adopt competitive strategies through enriched high-efficiency metabolic genes and symbiotic microbial recruitment to withstand resource competition. Full article

In northern China’s arid and semi-arid regions, evergreen trees demonstrate significant cold tolerance to natural low-temperature stress during winter. However, the metabolic strategies and their associated properties underlying their overwintering adaptation remain incompletely elucidated. This study aims to reveal the metabolic properties of natural low-temperature adaptation strategies in five evergreen trees through metabolomic analysis and to identify key metabolites and their dynamic variation patterns. The GC-TOF-MS platform was used to investigate seasonal differential metabolites in five evergreen trees across January, April, July, and October and further explore core differentially expressed metabolites responsive to low-temperature stress. The results demonstrated that the seasonal changes in the chlorophyll content of five evergreens exhibited distinct patterns, that significant differences were observed between Juniperus sabina L. and Picea meyeri R., Ammopiptanthus mongolicus M., Buxus sinica var. parvifolia M.Cheng, and Pinus tabuliformis C., and that no significant differences were found among the other tree species. A total of 427 metabolites were detected in the metabolome; when assessing seasonal dynamics, it was found that the types of differentially expressed metabolites in the five evergreens underwent significant changes. In spring, the differentially expressed metabolites included some carbohydrates, alcohols, organic acids, and lipids. During summer and autumn, the largest number of differentially expressed metabolites accumulated, mainly including carbohydrates, organic acids, and amino acid compounds. In winter, while Picea meyeri primarily accumulated carbohydrates, the remaining four species mainly accumulated organic acids, along with a small number of alcohols, phenylpropanoids, and polyketides. Three shared carbohydrate metabolites, L-threose, galactinol, and gluconic lactone, were commonly downregulated across all species. Additionally, coniferous trees collectively accumulated 3,6-anhydro-D-galactose, showing downregulation. The KEGG enrichment analysis of winter-accumulated metabolites revealed significant associations with the pentose phosphate pathway, amino acid metabolism, phenylpropanoid biosynthesis, the tricarboxylic acid cycle, and ascorbate–aldarate metabolism pathways. Through comparative analysis with the summer growth season, we ultimately identified the core differentially expressed metabolites of the five evergreens, providing potential metabolic markers for the breeding of cold-tolerant species. In summary, these findings provide critical metabolomic insights into how plants adapt to low temperatures, significantly enhancing our understanding of the metabolic foundations of cold tolerance in evergreen species. Full article

Understanding the complex interplay among altitudinal gradients, tree species diversity, structural attributes, and soil carbon (C) is critical for effective coniferous forest management and climate change mitigation. This study addresses a knowledge gap by investigating the effects of altitudinal gradient on coniferous tree diversity, biomass, carbon stock, regeneration, and soil organic carbon storage (SOCs) in the understudied temperate forests of the Hindu-Kush Kalam Valley. Using 120 sample plots 20 × 20 m (400 m²) each via a field inventory approach across five altitudinal gradients [E1 (2000–2200 m)–E5 (2801–3000 m)], we comprehensively analyzed tree structure, composition, and SOCs. A total of four coniferous tree species and 2172 individuals were investigated for this study. Our findings reveal that elevation indirectly influences species diversity, SOCs, and forest regeneration. Notably, tree height has a positive relationship with altitudinal gradients, while tree carbon stock exhibits an inverse relationship. Forest disturbance was high in the middle elevation gradients E2–E4, with high deforestation rate at E1 and E2. Cedrus deodara, the dominant species, showed the highest deforestation rate at lower elevations (R² = 0.72; p < 0.05) and regeneration ability (R² = 0.77; p < 0.05), which declined with increasing elevation. Middle elevations had the highest litter carbon stock and SOCs values emphasizing the critical role of elevation gradients in carbon sink and species distribution. The regeneration status and number of trees per ha in Kalam Valley forests showed a significant decline with increasing elevation (p < 0.05), with Cedrus deodara recording the highest regeneration rate at E1 and Abies pindrow the lowest at E5. The PCA revealed that altitudinal gradients factor dominate variability via PCA1, while the Shannon and Simpson Indices drives PCA2, highlighting ecological diversity’s independent role in shaping distinct yet complementary vegetative and ecological perspectives. This study reveals how altitudinal gradients shape forest structure and carbon sequestration, offering critical insights for biodiversity conservation and climate-resilient forest management. Full article

Pinus tabuliformis is a well-recognized woody mycorrhizae host plant growing in North China. EM fungi contribute to the host health and the stability of the forest ecosystem. However, ectomycorrhiae (EM) fungal community associated with this species is less documented. In this study, we examined EM fungal diversity and composition of P. tabuliformis from three sites in Inner Mongolia, China by using Illumina MiSeq sequencing on the rDNA ITS2 region. Our results showed that a total of 105 EM fungal operational taxonomic units (OTUs) were identified from 15 composite root samples, and the dominant lineages were /suillus-rhizopogon, /tomentella-thelephora, /tricholoma, /amphinema-tylospora, /wilcoxina, /inocybe, and /Sebacina. A high proportion of unique EM fungal OTUs (33, 31.4% of total OTUs) were detected, and some abundant OTUs preferred to exist in specific sites. The composition of EM fungal communities was significantly different among the sites, with soil, climatic, and spatial variables being related to the community variations. The EM fungal community assembly was mainly driven by environmental factors in deterministic processes. These findings suggest that this endemic Pinaceae species in China also harbored a rich and distinctive EM fungal community and deterministic processes played more important roles than stochastic in shaping the symbiotic fungal community. Our study improves our understanding of EM fungal diversity and community structure from the perspective of a single host plant that has not been investigated exclusively before. Full article

Tree crown detection of high-resolution UAV forest remote sensing images using computer technology has been widely performed in the last ten years. In forest resource inventory management based on remote sensing data, crown detection is the most important and essential part. Deep learning technology has achieved good results in tree crown segmentation and species classification, but relying on high-performance computing platforms, edge calculation, and real-time processing cannot be realized. In this thesis, the UAV images of coniferous Pinus tabuliformis and broad-leaved Salix matsudana collected by Jingyue Ecological Forest Farm in Changping District, Beijing, are used as datasets, and a lightweight neural network U-Net-Light based on U-Net and VGG16 is designed and trained. At the same time, the IP core and SoC architecture of the neural network accelerator are designed and implemented on the Xilinx ZYNQ 7100 SoC platform. The results show that U-Net-light only uses 1.56 MB parameters to classify and segment the crown images of double tree species, and the accuracy rate reaches 85%. The designed SoC architecture and accelerator IP core achieved 31 times the speedup of the ZYNQ hard core, and 1.3 times the speedup compared with the high-end CPU (Intel CoreTM i9-10900K). The hardware resource overhead is less than 20% of the total deployment platform, and the total on-chip power consumption is 2.127 W. Shorter prediction time and higher energy consumption ratio prove the effectiveness and rationality of architecture design and IP development. This work departs from conventional canopy segmentation methods that rely heavily on ground-based high-performance computing. Instead, it proposes a lightweight neural network model deployed on FPGA for real-time inference on unmanned aerial vehicles (UAVs), thereby significantly lowering both latency and system resource consumption. The proposed approach demonstrates a certain degree of innovation and provides meaningful references for the automation and intelligent development of forest resource monitoring and precision agriculture. Full article

Bursaphelenchus xylophilus is a pine wood nematode capable of destroying pine forests. Exploring the genes providing resistance to this pathogen and understanding their resistance mechanisms is thus necessary and constitutes an effective way to tackle this problem. We used Pinus tabuliformis Carriere to dissect its response to B. xylophilus strain BxFC. The 30 d inoculation results showed that the P. tabuliformis germplasms exhibited a wide resistance spectrum. Some lines were sensitive with the needles fully wilted and the MDA content and the relative conductivity of needles greatly increased, while some lines demonstrated strong resistance with good needle vigor and better physiological conditions. Moreover, the transcriptome analysis revealed 7928 differentially expressed genes (DEGs) between the resistant and sensitive germplasm pools, including 3754 upregulated and 4174 downregulated genes in the resistant lines. These DEGs were specially enriched in the pathways of plant–pathogen interaction (318 genes), phenylpropanoid biosynthesis (108 genes), ubiquitin-mediated proteolysis (47 genes), carotenoid biosynthesis (18 genes), and monoterpenoid biosynthesis (9 genes). Accordingly, P. tabuliformis utilized multiple ways to control the proliferation and activity of B. xylophilus, such as immune response, ubiquitination, thickening plant cell walls, and increasing its terpenoid and antioxidant contents. Our results could thus help in better understanding the resistance process of P. tabuliformis against B. xylophilus and offer some new strategies and gene resources for a molecular breeding program of resistant P. tabuliformis. Full article

The rapid and precise acquisition of forest stand parameters is a key challenge in forest resource assessment. Terrestrial laser scanning (TLS) provides a fast and accurate method, but its accuracy is influenced by factors like tree segmentation parameters. This study focuses on Pinus tabuliformis plantations in the Caijiachuan watershed, Jixian, Shanxi, on the Loess Plateau. Based on field survey data, including tree number, height (H), diameter at breast height (DBH), and biomass, high-precision point cloud data were acquired using TLS. A comparative shortest path (CSP) algorithm was used for individual tree segmentation to investigate the effect of parameter selection on measurement accuracy. The results show that minimum tree height has a significant impact on segmentation accuracy. As the minimum tree height increased from 3.0 to 5.5 m, the recall rate (R) decreased while the precision (P) increased. The highest precision (F-score = 0.9470) and biomass estimation accuracy (0.9066) were obtained with a minimum tree height of 4.5 m, and the best extraction accuracies for H and DBH (0.9677 and 0.9518) were obtained at 5.0 m. Optimizing the minimum tree height parameter improves segmentation accuracy, thereby enhancing the use of TLS for soil and water conservation on the Loess Plateau. Full article

Microbial residual carbon (MRC) is a key component of soil organic carbon (SOC) and crucial for SOC stabilization, contributing to the formation of a stable soil carbon pool. However, the accumulation patterns of MRC in different plantation forest types remain unclear. In this study, based on the principle of site condition similarity and supported by field investigations, soils from Populus alba, Salix matsudana Koidz, and Pinus tabuliformis in Beijing were selected as the research objects. The physical and chemical properties of the soils, as well as the microbial residual carbon content, were measured. Correlation analysis and redundancy analysis (RDA) were then conducted to explore the accumulation patterns of microbial residual carbon across different plantation forest types and to identify the factors influencing these patterns. Results showed that fungal residue carbon, bacterial residue carbon, and total MRC were highest in Populus alba, followed by Salix matsudana Koidz and Pinus tabuliformis. The contributions of fungal, bacterial, and total MRC to SOC were greatest in Populus alba, followed by Pinus tabuliformis and Salix matsudana Koidz. In this study, Populus alba were found to be more effective in sequestering microbial residue carbon. Fungal residue carbon content and its contribution to SOC were greater than bacterial residue carbon in all plantation types. Soil organic carbon, nitrate nitrogen, and available potassium were significantly correlated with both MRC content and its contribution to SOC. These findings deepen our understanding of microbial-driven soil carbon accumulation and provide a foundation for enhancing the carbon sequestration potential of plantation forests. Full article