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Background and Aims Pinus massoniana Lamb. is an important conifer forestry species in south China, but soil fertility has declined over time in monoculture plantations. Knowledge about how P. massoniana uses phosphorus (P) by distributing it among five biochemical fractions and how intercropping with broadleaf Castanopsis hystrix alters that pattern may inform long-term plantation management. Methods We studied a single P. massoniana plantation that was split in half into a monoculture and a P. massoniana / C. hystrix intercropped plantation 25 years after establishment. We measured photosynthesis and leaf concentrations of total P, P allocated to five chemical fractions and total nitrogen (N). We also measured soil N concentrations. Results Intercropping C. hystrix with 25-year-old P. massoniana for a further 34 years had no significant impact on P. massoniana total stem volume, although intercropped P. massoniana trees were 5 m taller . Intercropping with C. hystrix increased timber biomass due to the additional C. hystrix stems. Growth of C. hystrix was likely more limited by P than that of P. massoniana in both plantations. Total P concentration and its allocation among fractions declined with increasing leaf age, but differed in the two species. Leaf P-resorption efficiency in intercropped P. massoniana was 79%, which was about 15% greater than that in P. massoniana monoculture and in the intercropped C. hystrix . The greater P-resorption efficiency in intercropped P. massoniana than in monoculture was due to greater mobilization of P from all fractions, except phospholipids. Bulk soil N concentration was 50% greater in the intercropped plantation than in monoculture. Conclusion Adding C. hystrix to an P. massoniana plantation was effective at increasing wood yield without compromising productivity of P. massoniana .

This study investigated the nutritional components of Castanopsis hystrix seeds and evaluated their potential commercial value, regarding multi-function management of C. hystrix plantations. The following nutritional components of Castanopsis hystrix seeds were determined according to national standards: starch, fat, protein, reducing sugars, and amino acids. The chemical composition of their 50% benzene-alcohol(v/v) extracts was analyzed by GC-MS. Results showed that the contents of water, starch, fat, protein, and reducing sugar in the seeds were 36.08%, 68.11 g/100g, 0.3 g/100g, 3.98 g/100g, and 0.75 g/100g, respectively. The total amino acid content in the seeds is 3.42 g/100g, containing 16 kinds of amino acids, with 8 essential amino acids, which amount to 1.09g/100g. The amino acid SRC value was 84.02, indicating high nutritional value. A total of 26 compounds were identified in the extract of these seeds, with the highest content of aldehydes. The main compounds were 5-hydroxymethylfurfural (23.37%), melezitose (15.88%), palmitic acid (9.04%), and stearic acid (5.23%). The above analysis indicates that Castanopsis hystrix seeds have high nutritional value, as well as potential antioxidant and anti-tumor properties, which may have the potential to be used in food and medicine fields, with broad application prospects.

Castanopsis hystrix is a valuable native, broad-leaved, and fast-growing tree in South China. In this study, 15 phenotypic traits and 32 simple sequence repeat (SSR) markers were used to assess the genetic diversity and population structure of a natural population of C. hystrix and to construct a core germplasm collection by a set of 232 accessions. The results showed that the original population of C. hystrix had relatively high genetic diversity, with the number of alleles (Na), effective number of alleles (Ne), observed heterozygosity (Ho), expected heterozygosity (He), Shannon’s information index (I), and polymorphism information content (PIC) averaging at 26.188, 11.565, 0.863, 0.897, 2.660, and 0.889, respectively. Three sub-populations were identified based on a STRUCTURE analysis, indicating a strong genetic structure. The results from the phylogenetic and population structures showed a high level of agreement, with 232 germplasms being classified into three main groups. The analysis of molecular variance (AMOVA) test indicated that 96% of the total variance was derived from within populations, which revealed a low differentiation among populations. A core collection composed of 157 germplasms was firstly constructed thereafter, of which the diversity parameters non-significantly differed from the original population. These results revealed the genetic diversity and population structure of C. hystrix germplasms, which have implications for germplasm management and genome-wide association studies on C. hystrix, as well as for core collection establishment applications in other wood-producing hardwood species.

Fagaceae species dominate forests and shrublands throughout the Northern Hemisphere, and have been used as models to investigate the processes and mechanisms of adaptation and speciation. Compared with the well-studied genus Quercus , genomic data is limited for the tropical-subtropical genus Castanopsis . Castanopsis hystrix is an ecologically and economically valuable species with a wide distribution in the evergreen broad-leaved forests of tropical-subtropical Asia. Here, we present a high-quality chromosome-scale reference genome of C. hystrix , obtained using a combination of Illumina and PacBio HiFi reads with Hi-C technology. The assembled genome size is 882.6 Mb with a contig N50 of 40.9 Mb and a BUSCO estimate of 99.5%, which are higher than those of recently published Fagaceae species. Genome annotation identified 37,750 protein-coding genes, of which 97.91% were functionally annotated. Repeat sequences constituted 50.95% of the genome and LTRs were the most abundant repetitive elements. Comparative genomic analysis revealed high genome synteny between C. hystrix and other Fagaceae species, despite the long divergence time between them. Considerable gene family expansion and contraction were detected in Castanopsis species. These expanded genes were involved in multiple important biological processes and molecular functions, which may have contributed to the adaptation of the genus to a tropical-subtropical climate. In summary, the genome assembly of C. hystrix provides important genomic resources for Fagaceae genomic research communities, and improves understanding of the adaptation and evolution of forest trees.

Castanopsis hystrix is one of the main timber trees grown in China. However, severe shortage of natural seeds and the difficulty of explant regeneration has limited seedling supply. As such, there is a need for research on asexual multiplication of C. hystrix . This study established a rapid propagation technology system for C. hystrix genotypes, including explant treatment, proliferation, and rooting. HZ (a modified MS medium) supplemented with 4.4 μM BA and 0.5 μM IBA was found to be the optimal medium for shoot sprouting. The maximum proliferation coefficient and the number of effective shoots was obtained on HZ medium supplemented with 2.6 μM BA and 1.0 μM IBA, were 3.00 and 5.63, respectively. A rooting rate of 83.33% was achieved using half-strength HZ medium supplemented with 3.2 μM NAA. Adding vitamin C (80 mg⋅l –1 ) for 7 days in a dark environment reduced the browning rate, while increasing the proliferation rate. Additionally, through cytological observation, we established how and where adventitious roots occur. The survival rate of transplanted plantlets was > 90%. This is the first report of an in vitro regeneration technique that uses stem segments of mature C. hystrix as explants.

Castanopsis hystrix is a major community-building species in the top communities of southern subtropical China, with a high natural regeneration capacity. However, excessive logging and the introduction of exotic tree species have substantially reduced the area of natural forest patches of Castanopsis hystrix, and seedling regeneration is essential for the long-term continuation of Castanopsis hystrix populations. To explore the effects of light intensity on the seedling emergence and early growth of Castanopsis hystrix, shading experiments were conducted under four shading treatments (0%, 40%, 60%, and 80%). The growth, biomass accumulation, and distribution, the quality index of seedlings, the morphology and structure of the root systems of seedlings, and the leaf chlorophyll content and chlorophyll fluorescence properties of seedlings under different shading treatments were analyzed. The results displayed the following: (1) Shade intensity impacts growth of Castanopsis hystrix seedlings and biomass allocation, with optimal results observed at 60% shade, leading to the promotion of organic matter production in leaves and the limitation of stem growth. (2) Using a multi-indicator composite index, it was determined that seedling quality for Castanopsis hystrix peaks at 60% shade intensity. (3) Shade significantly impacts the morphology and structure of Castanopsis hystrix’s root system, with most root characteristics peaking at 60% shade, indicating a substantial increase in root development compared to no-shade conditions. (4) The D-values indicated the most suitable shade intensity for seedling growth to be 60%, suggesting that Castanopsis hystrix seedlings are sensitive to light and excessive light can be detrimental to their growth. (5) The 60% shade treatment showed the maximum values of chlorophyll fluorescence characteristics and photochemical activity, with variations in energy conversion efficiency and dissipation reflected in parameters like photochemical burst coefficient (qP), photochemical burst coefficient (qN), the actual photometric yield of PSII under light acclimation (YII), and the maximum photosynthetic electron transport rate in photoinhibition (ETR), thereby supporting seedling growth and maintaining the normal function of photosynthetic organs. In conclusion, 60% shade treatment can effectively improve the growth and photosynthetic characteristics of Castanopsis hystrix seedlings and promote the accumulation of nutrient elements, ultimately promoting their growth.

Climate warming poses a great threat to ecosystems worldwide, which significantly affects the geographical distribution and suitable growth area of species. Taking Castanopsis hystrix Miq. as the research object, the potentially suitable cultivation regions under present and future climatic emission scenarios in China were predicted based on the MaxEnt model with 360 effective individual distributions and eight environmental variables. The min temperature of coldest month (bio6), precipitation of driest month (bio14), and precipitation of warmest quarter (bio18) are three leading factors affecting the geographical distribution area of C. hystrix Miq. The suitable cultivation regions of C. hystrix Miq. range from 18°–34° N, 89°–122° E in central and southern China and cover an area of 261.95 × 104 km2. The spatial pattern of C. hystrix Miq. will migrate to the southern region of low latitudes with a decreasing suitable area when in ssp1-2.6, and to the southwestern region of low latitudes or expand to the northeast region at high latitudes in ssp5-8.5, with an increasing suitable area; no significant change on the spatial pattern in ssp2-2.4. For ssp1-2.6 or ssp2-4.5 climate scenarios, the southern region of high latitudes will be appropriate for introducing and cultivating C. hystrix Miq., and the cultivation area will increase. For ssp5-8.5, its cultivation will increase and expand to the northeast of high-latitude areas slightly.

Castanopsis hystrix, a timber resource from Southeast Asia, is characterized by rapid growth and high yield, but plantation quality and efficiency improvements are required. Twenty-year-old C. hystrix experimental forests in Yulin, Liuzhou, and Pingxiang in Guangxi Province, China, comprising 21 open-pollinated half-sib families, were used in this study. Genetic variations in the growth (tree height, diameter at breast height (DBH), and volume (V)) and morphological (height to live crown base (HCB), crown width (CW), and branch angle) traits were assessed, and the genetic parameters were estimated to clarify the genotype × environment interaction effects. The average values for the tree height, DBH, V, HCB, CW, and branch angle were 16.33 m, 17.25 cm, 0.21 m3, 6.68 m, 2.15 m, and 45.45°, respectively. The most important sources of variance for the tree height, DBH, V, and HCB were the block and family, whereas the location, family, and family × location had significant impacts on the tree height, DBH, V, and HCB (p < 0.01). The family heritability for each trait was 0.35, 0.38, 0.62, and 0.19, respectively. Excellent families with strong adaptability and genetic stability were identified using BLUP–GGE biplots for single and multiple traits. The results provide a theoretical basis for the efficient cultivation of C. hystrix in South China.

Castanopsis hystrix, a dominant canopy species in the subtropical forests of south China, is renowned for its high natural regeneration ability. Therefore, this paper took C. hystrix as the subject of study. Examining the variations in microbial diversity and community composition within the soil rhizosphere of C. hystrix across different elevation gradients, we explored how this community-forming species impacts soil microbial diversity and community structure and how soil microorganisms respond to changes in soil physicochemical properties due to altitude gradients. The results show: (1) soil samples from five altitudes established 1078 fungal OTU and 5595 bacterial OTUs. (2) Basidiomycota and ascomycota are dominant fungal groups in the soil, with Acidobacteria being the predominant bacteria for C. hystrix. (3) As altitude increases, fungal communities’ richness and diversity index peaks at 849 m; for bacterial communities, the richness index peaks at 387 m and the diversity index at 670 m. (4) Total phosphorus (TP), nitrate nitrogen (NO3−-N), hydrolyzed nitrogen (HN), total nitrogen (TN), and organic matter (SOM) are significant environmental factors affecting fungal community structure. At the same time, available potassium (AK) significantly influences the composition of bacterial communities. The study underscores the intricate relationship between altitude, soil properties, and microbial diversity, offering insights into how C. hystrix contributes to ecosystem resilience. Recommendations include enhancing phosphorus supplementation and controlling nitrogen deposition to maintain forest ecological integrity, additionally, the supply of potassium in the soil should also be a key consideration. Further research is necessary to understand the broader implications for biodiversity conservation and adaptive management strategies in the face of climate change.

Monitoring tree growth helps operators better understand the growth mechanism of trees and the health status of trees and to formulate more effective management measures. Computer vision technology can quickly restore the three-dimensional geometric structure of trees from two-dimensional images of trees, playing a huge role in planning and managing tree growth. This study used binocular reconstruction technology to measure the height, canopy width, and ground diameter of Castanopsis hystrix and compared the growth differences under different nitrogen levels. In this research, we proposed a wavelet exponential decay thresholding method for image denoising. At the same time, based on the traditional semi-global matching (SGM) algorithm, a cost search direction is added, and a multi-line scanning semi-global matching (MLC-SGM) algorithm for stereo matching is proposed. The results show that the wavelet exponential attenuation threshold method can effectively remove random noise in red cone images, and the denoising effect is better than the traditional hard-threshold and soft-threshold denoising methods. The disparity images produced by the MLC-SGM algorithm have better disparity continuity and noise suppression than those produced by the SGM algorithm, with more minor measurement errors for C. hystrix growth factors. Medium nitrogen fertilization significantly promotes the height, canopy width, and ground diameter growth of C. hystrix. However, excessive fertilization can diminish this effect. Compared to tree height, excessive fertilization has a more pronounced impact on canopy width and ground diameter growth.