Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is a widely grown gymnosperm in China. Phosphorus (P) is an indispensable nutrient for the growth of Chinese fir. Inorganic phosphate (Pi) deficiency exists in soils of many Chinese fir planting area regions, and the trees themselves have limited efficiency in utilizing P from the soil. Ethylene is important in regulation responses to nutrient deficiencies. However, little is known about how ethylene signals participate in Pi stress in Chinese fir. A total of six different treatments were performed to reveal the transcript levels of Chinese fir under Pi, ethephon (an ethylene-releasing compound), and CoCl2 (cobalt chloride, an ethylene biosynthesis inhibitor) treatments. We assembled a full-length reference transcriptome containing 22,243 unigenes as a reference for UMI RNA-seq (Digital RNA-seq). There were 586 Differentially Expressed Genes (DEGs) in the Pi starvation (NP) group, while DEGs from additional ethephon or CoCl2 in NP were 708 and 292, respectively. Among the DEGs in each treatment, there were 83 TFs in these treatment groups. MYB (v-myb avian myeloblastosis viral oncogene homolog) family was the most abundant transcription factors (TFs). Three ERF (Ethylene response factor) family genes were identified when only ethylene content was imposed as a variable. Enrichment analysis indicated that the ascorbate and aldarate metabolism pathway plays a key role in resistance to Pi deficiency. This study provides insights for further elucidating the regulatory mechanism of Pi deficiency in Chinese fir.
Forest plantation, either through afforestation or reforestation, has been suggested to reverse and mitigate the process of deforestation. However, uncertainties remain in the potential of plantation forest (PF) to sequestrate carbon (C) and nitrogen (N) compared to natural forest (NF). Soil C and N stocks require a critical and updated look at what is happening especially in the context of increasing rate of land use change and climate change. The current study was conducted in China's Eastern forest to estimate soil C and N stocks in six depth layers (0-10, 10-20, 20-40, 40-60, 60-80 and 80-100 cm) and two forest types (NF and PF) at four sites along climate factors gradient. The results showed that the overall mean soil C and N amounts to a depth of 20 cm ranged from 2.6 ± 1.1 Mg ha-1 to 38.6 ± 23.1 Mg ha-1, and soil nitrogen stock ranged from 0.2 ± 0.1 Mg ha-1 to 3.3 ± 1.5 Mg ha-1. Moreover, a loss of C stock was observed at Qingyuan (QY) by -7%, Dinghushan (DH) by -26%, Jianfengling (JF) by -13% while that of N stock was observed at QY (-8%), DH (-19%) and JF (-12%) at both depth layers. These results indicate that NFs have a better capacity to accumulate soil C and N. The soil C and N decreased from the southeast to the northeast and increased from tropical to temperate mixed forests zone in the eastern part of the study area. The C and N stock mainly occurred in the topsoil and decreased significantly with depth. Moreover, soil C and N stocks increased with age of plantation. This study provides an overview of the current spatial distribution and soil stocks of C and N, as well as the effects of environmental factors on soil C and N stocks. It also indicated that, although mean annual temperature and mean annual precipitation are the key factors affecting the variations in soil C and N, their vertical and horizontal distribution differed in various aspects.
Abstract Background : Under natural conditions, soil nutrients are heterogeneously distributed, and plants have developed adaptation strategies, such as root morphological plasticity and/or physiological plasticity, to efficiently forage patchily distributed nutrient. Most previous studies examined either patch strength or patch size separately and focused mainly on root morphological plasticity, thus the effects of both patch strength and size on morphological and physiological plasticity are not well understood. In this study, we examined the foraging strategy of Neyraudia reynaudiana (Kunth) Keng ex Hithc, a pioneer grass colonizing degraded sites, with respect to patch strength and size in heterogeneously distributed phosphorus (P), and how foraging patchily distributed P affects total plant biomass. Plants were grown in sand-culture pots divided into ½, ¼, 1/6 compartments and full size and supplied with 0 + 0/30, 0 + 7.5/30 and 7.5 + 0/30 mg P/kg dry soil as KH2PO4 or 0 + 15/15, 0 + 18.5/ 18.5, 7.5 + 15/15 mg kg−1 in the homogenous treatment. The first amount was the P concentration in the central region, and that the second amount was the P concentration in the outer parts of the pot. Results : After 3 months of growth under experimental conditions, significantly (p < 0.05) high root elongation, root surface area, root volume and average root diameter was observed in large patches with high patch strength. Roots absorbed significantly more P in P-replete than P-deficient patches. Whole plant biomass was significantly higher in larger patches with high patch strength than small patches and homogeneous P distribution. Conclusion : The result demonstrates that root morphological and physiological plasticity are important adaptive strategies for foraging patchily distributed P and the former is largely determined by patch strength and size. The results also establish that foraging patchily distributed P resulted in increased total plant biomass compared to homogeneous P distribution.
In terms of the types of phytoremediation,screening of hyperaccumulators,physiological and molecular mechanisms of hyperaccumulators′ absorption of accumulated heavy metals,the advances in phytoremediation in heavy metal contaminated soil at home and abroad are reviewed,meanwhile the current status and prospects are elaborated.
Objective Rhizosphere soil nutrients and bacterial diversity of four broad-leaved tree species underplanted in Chinese fir plantation with different stand density levels were analyzed to reveal characteristics of the rhizosphere soil environment and selection of suitable underplanted tree species. Methods Chinese fir plantation with three density levels (900, 1,200, and 1,875 stems ha –1 , respectively) were selected and underplanted with Michelia macclurei , Schima superba , Phoebe zhennan , and Tsoongiodendron odorum . The rhizosphere soil nutrients and bacterial community of the broad-leaved tree species were determined after 4 years. Results Significant differences in rhizosphere nutrient content were detected among different tree density levels, where the contents of total K, available K and available P in 900 stems ha –1 stands were significantly higher than the other stocking density levels. There were also significant differences in the contents of total C, total N, total K, available K and available P in the rhizosphere soils of the four trees species, while there were no significant differences in pH and total P. Rhizosphere soil nutrient contents were higher under S. superba and M. macclurei than under P. zhennan and T. odorum . The rhizosphere soil nutrient contents and bacterial diversity decreased with the increase of stand density, and the bacterial diversity showed significant differences in the rhizosphere soils of P. zhennan , T. odorum and S. superba when underplanted in different stand densities. The bacterial diversity was positively correlated with the available P content of rhizosphere soils, suggesting that soil available P content plays an important role in shaping the structure of bacterial community. Conclusion The nutrient contents and bacterial diversity of rhizosphere soils of underplated broad-leaved species decreased with increasing stand density of Chinese fir plantation. Rhizosphere soils of M. macclurei and S. superba were rich in nutrient contents and bacterial diversity. Thus, low density of Chinese fir plantation (900 stems ha –1 ) underplanted with M. macclurei and S. superba is suitable for the establishment of mixed forest, which will facilitate better tree growth and maintaining soil fertility to realize sustainable management of forests.
Significant market value discrepancies exist between clear and knotty Chinese fir (Cunninghamia lanceolata) wood, distinguished not only by their aesthetic variations but also by their distinct material properties. This study aimed to explore the differences in physical and mechanical properties between clear and knotty Chinese fir wood. Nine standard trees were chosen from a 26-year-old Chinese fir plantation for the experiment. Subsequent to felling, trunk segments below 7 m in length were transported to the laboratory. For each tree, detailed preparations were made to obtain clear and knotty wood specimens, and these distinct wood specimens were subjected to thorough physical and mechanical assessments. The results revealed significant variations in properties between clear and knotty Chinese fir wood. The shrinkage and swelling coefficients of knotty wood were generally lower than those of clear wood, except for higher radial and tangential air-dry shrinkage. Specifically, the swelling ratio of knotty wood was at least 0.40% lower, and the oven-dry shrinkage was at least 0.58% lower than that of clear wood. Knotty wood exhibited higher air-dry and oven-dry densities, with its density being at least 0.15 g cm−3 higher than that of clear wood. However, its mechanical properties, including tensile strength, compression strength, impact bending strength, bending strength, and modulus of elasticity, were lower than those of clear wood. For instance, the tensile strength parallel to the grain of clear wood was 40.63 MPa higher, the modulus of elasticity was 1595 MPa higher, and the impact bending strength was 27.12 kJ m−2 greater than that of knotty wood. Although the tangential and radial surface hardness of knotty wood increased significantly compared to clear wood, the end hardness remained relatively lower. Overall, knotty Chinese fir wood displayed enhanced physical properties, whereas clear wood showcased superior mechanical properties. Careful selection between clear and knotty wood is recommended based on the specific requirements of wooden structural elements to optimize timber resource utilization.
Forest plantation, either through afforestation or reforestation, has been suggested to reverse and mitigate the process of deforestation.However, uncertainties remain in the potential of plantation forest (PF) to sequestrate carbon (C) and nitrogen (N) compared to natural forest (NF).Soil C and N stocks require a critical and updated look at what is happening especially in the context of increasing rate of land use change and climate change.The current study was conducted in China's Eastern forest to estimate soil C and N stocks in six depth layers (0-10, 10-20, 20-40, 40-60, 60-80 and 80-100 cm) and two forest types (natural forest and plantation) at four sites along climate factors gradient.The results showed that the overall mean soil C and N amounts to a depth of 20 cm ranged from 2.6 ± 1.1 Mg ha-1 to 38.6 ± 23.1 Mg ha-1, and soil nitrogen stock ranged from 0.2 ± 0.1 Mg ha-1 to 3.3 ± 1.5 Mg ha-1.Moreover, a loss of C stock was observed at Qingyuan (QY) by -7%, Dinghushan (DH) by -26%, Jianfengling (JF) by -13% while that of N stock was observed at QY (-8%), DH (-19%) and JF (-12%) at both depth layers.These results indicate that natural forests (NF) have a better capacity to accumulate soil C and N. The soil C and N decreased from the southeast to the northwest and increased from tropical to coldtemperate zone in the eastern part of the study area.The C and N stock mainly occurred in the topsoil and decreased significantly with depth.Moreover, soil C and N stocks increased with age of plantation.This study provides an overview of the current spatial distribution and soil stocks of C and N, as well as the effects of environmental factors on soil C and N stocks.It also indicated that, although mean annual temperature (MAT) and mean annual precipitation (MAP) are the key factors affecting the variations in soil C and N, their vertical and horizontal distribution differed in various aspects.
The results were as follows: there were significant differences in nitrogen utilization efficiencies among different Chinese fir clones. As the degree of nitrogen stress increased, nitrate reductase activities and light saturation points of different clones decreased, CO_(2) compensation pints increased and responses of different clones to nitrogen stresses became more obvious. The tested cloens may be classified into three categories: strong, weak and intermedite capacity to nitrogen stresses according to their responses to nitrogen stress. Among the tested clones, No. 163 and No. 301 were the High-nitrogen-efficiency clones that could produce high yield in the site of low nitrogen concentration and ought to be popularized for poor site. These clones have practical significance to buffer the increasingly sever soil degradation and provide a new approach to control the productivity decline for successive planting of Chinese fir.
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