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Comprehensive Evaluation and Index Screening of Salt Tolerance for Three Afforestation Specie Seedlings in China
GAN Hong-hao, GONG Shuai, LIU Hao, CHU Jian-min
, Available online  , doi: 10.12403/j.1001-1498.20230319
Objective To study the differences in salt tolerance among the Melia azedarach, Ulmus pumila and Robinia pseudoacacia seedlings and to select the evaluation indexes of salt tolerance. Method Based on the one-year-old seedlings of M. azedarach, U. pumila and R. pseudoacacia, the effects of different NaCl concentrations (0, 100, 200 and 300 mmol·L−1) on the seedling biomass, physiological and biochemical indexes were analyzed. Result (1) NaCl stress inhibited the biomass of M. azedarach, U. pumila and R. pseudoacacia seedlings, decreased the relative water content of leaves and increased the electrolyte permeability. (2) The contents of chlorophyll a and b in R. pseudoacacia decreased significantly with the increase in NaCl concentration. But the chlorophyll content in M. azedarach and U. pumila seedlings only decreased significantly under 300 mmol·L−1 NaCl treatment. The photosynthetic parameters Pn, Gs, Ci and E decreased under NaCl stress in the 3 tree seedlings, but the stomatal limitation and water use efficiency increased. Meanwhile, the concentrations of free proline and soluble protein, as well as the activities of CAT and APX in roots and leaves also increased. (3) NaCl stress changed the ion balance in the roots and leaves of the 3 tree seedlings. The Na+ concentration in roots and leaves and K+ concentration in leaves of the 3 tree seedlings significantly increased under NaCl stress, but the concentration of K+ in roots, as well as the concentrations of Mg2+ and Ca2+ in roots and leaves had differential changes. Conclusion The seedlings of U. pumila have the strongest salt tolerance, followed by M. azedarach, R. pseudoacacia. The concentrations of free proline and soluble protein in roots, CAT and APX activities in roots and leaves, Ca2+ in roots and Na+ in leaves are highly correlated with salt tolerance of the 3 tree seedlings, which can be used as the evaluation indexes of salt tolerance.
Diversity and Community Stability of Understory Vegetation in the Pinus massoniana Forest after Transformation in Thousand-island Lake Area
ZHOU Xiu-bin, XU Yu-hua, LIU Min, LUO Chao, PAN Wen, LI Sheng
, Available online  , doi: 10.12403/j.1001-1498.20230348
Objective Transforming Pinus massoniana coniferous forest into broadleaved forest is beneficial to improving the structure and function of forest ecosystem and has significant influence on the regeneration and succession of understory vegetation. The analysis of the diversity and community stability of understory vegetation after forest transformation can provide reference for sustainable forest management. Method In this study, based on the four types of stand transformation (i.e., I thinning and promoting regeneration, II thinning and planting broadleaf trees, III clear cutting and promoting regeneration, clear cutting and IV clear cutting and planting broadleaf trees) of Pinus massoniana forests in Thousand-island Lake Forest area, Chun’an county, and control treatment (V no-transformation forest )), the species composition, diversity and community stability of understory vegetation were investigated. The relationship between understory species composition and stand factors was analyzed, and the relationship between species diversity and community stability was also explored. Result The difference of understory dominant species among different stands was lower in shrub layer than in herb layer. The understory species diversity in control group was significantly lower than that in transformed stand (P < 0.05) and the species diversity of herb layer in type IV was significantly higher than that in other types (P < 0.05). The stand factors could explain about 40% of understory species variation and had higher effect on the species composition of herb layer than that of shrub layer. Among these, the canopy density was the most important factor. In the early stage of stand transformation, the understory community stability in mode V was the best, followed by I, II, III, and IV. The community stability of shrub layer had low correlation with species diversity, while the stability of herb layer was negatively correlated with species diversity (P < 0.05). Conclusion In the early stage of broad-leaf transformation of P. massoniana forest in Thousand-island Lake area, the diversity of herbaceous layer was significantly improved mainly by reducing canopy density, but the stability of understory vegetation community was low under clear cutting treatments. Therefore, considering vegetation diversity and community stability, appropriate thinning and tending measures can promote the development of understory vegetation in P. massoniana forest.
Selection of Reference Genes for Gene Expression Analysis in Seed Development of Xanthoceras sorbifolium Bunge
LI Lin-kun, LIANG Chong-jun, NING Chu-long, ZHANG Wei, JIANG Guo-Wei, ZHANG Xin, WANG Li-bing
, Available online  , doi: 10.12403/j.1001-1498.20230291
: Objective : To assess the suitability of the ACT gene for gene expression analysis in seed development of Xanthoceras sorbifolium, and to identify the most stable reference genes for gene expression analysis in X. sorbifolium. Method : In this study, four mathematical algorithms (ΔCT, BestKeeper, NormFinder, geNorm) were carried out for evaluating the expression stability of 12 candidate reference genes based on the web-based tool RefFinder. Result : The RefFinder result showed that the gene PP2A performed the best, followed byTip41, EF-1α,18r, UCE, β-TUB, UBQ, α-TUB, CYP, SAM, ACT, and GADPH at the different seed development stages in X. sorbifolium , and the gene also had the highest score, followed by Tip41, CYP, 18r, UBQ, SAM, EF-1α, UCE, GADPH, α-TUB, ACT, and β-TUB at various tissues. Conclusion : PP2A and Tip41 are the two most stable reference genes for gene expression analysis in X. sorbifolium.
Niche and Interspecific Association of Dominant Species in Phoebe sheareri Natural Community
LU Yun-feng, YANG An-na, WANG Hao, LIU Wei, ZHANG Jun-hong, LOU Lu-huan, TONG Zai-kang
, Available online  , doi: 10.12403/j.1001-1498.20230245
Objective In order to explore the interspecific correlations and the stability of Phoebe sheareri natural community. Method Based on field sample survey, the ecological niche characteristics and interspecific associations of dominant species in the arbor layer and shrub layer of P. sheareri community were studied by through species composition, important value, niche breadth, niche overlap index, variance ratio method, and χ2 test. Result The important value, Levins niche breadth, and Shannon-Weaver niche breadth of P. sheareri were the largest in the investigated communities, indicating that both the resource utilization degree and competitive advantage were strong. The dominant species in the arbor layer showed an overall insignificant positive association (VR=1.247, χ20.95(12)>W>χ20.05(12)), while the shrub layer showed an overall insignificant negative association (VR=0.674, χ20.95(36)>W>χ20.05(36)), indicating that the stability of the arbor layer was higher than that of the shrub layer. The χ2 test result showed that the positively associated species pairs were more than the negatively onepairs, and the ratio of positive to negative association of arbor layer and shrub layer were 1.8∶1 and 1.5∶1, respectively. The majority of species pairs were not significantly associated, indicating that the ecological characteristics of most dominant species in the P. sheareri community were relatively consistent. Conclusion The P. sheareri community was is relatively stable. However, appropriate artificial tending practices should be carried out to promote the natural regeneration of these P. sheareri populations.
Comprehensive Selection of 29-year-old for Provenances/ Families of Teak (Tectona grandis Linn.f.) in Southwestern Yunnan
LIANG Kun-nan, ZHANG Rong-gui, HUANG Gui-hua, CHU Yong-xing, WANG Xian-bang, SHI Wen-ge
, Available online  , doi: 10.12403/j.1001-1498.20230324
Objective Through the comprehensive evaluation of the adaptability, growth and form quality traits of teak(Tectona grandis Linn.f.) forests (provenance / family) of early and 29-year-old established in southwestern Yunnan, the purpose is to select the superior provenances / families of teak with strong adaptability, fast growth and excellent form quality for the local region. Method Thirty-four provenances and families of teak were collected from China and abroad. Using a completely random block design with (2 × 2) plant plots and 8 replicates to establish trial plantation, the conservation rate and growth difference of the early 2-8 year old and 29-year old trees were investigated, analyzed and compared. The conservation rate, the growth and quality traits of dominant trees of 29-year old provenances/families were analyzed by principal component analysis, and excellent provenances/families were evaluated comprehensively. Result There was no significant difference in the preservation rate between the 2-8-year-old teak provenances/families in the early stage, while the difference in the preservation rate between the 29-year-old provenances/ families was extremely significant. However, the differences in growths and quality traits between 2-8-year-old or 29-year-old provenances / families were extremely significant. The average tree height, average DBH and average tree volume of 2-8-year-old best provenances / families were 1.38-1.91 times, 1.63-2.18 times and 3.82-5.17 times of the worst growing ones, respectively. The average tree height, average DBH, average tree volume, stem straightness and trunk height of 29-year-old dominant trees from the best provenances were 1.84 times, 1.87 times, 4.84 times, 2.18 times and 12.89 times of those from the worst provenances, respectively. Greater yield-increasing benefits can be obtained through the selection of excellent provenance / family. The preservation rate and growth traits of dominant trees of 29-year-old provenances/families were significantly correlated with the growth traits of 4-8-year-old dominant trees. The stem straightness of dominant trees of 29-year-old provenances / families was significantly correlated with the growth traits of dominant trees, and the tree height of dominant trees was significantly correlated with the average tree height and individual volume growth of dominant trees. The cumulative contribution rate of the first three principal components of 29-year-old provenances / families preservation rate, growth and form quality traits was 97.63%. According to the comprehensive score in the first three principal components of the provenances / families, seven excellent provenances / families (8410、8603、8407、8602、85131、1007 and 7564#)were selected according to the selection rate of 20%. Conclusion The genetic gains of dominant tree height, DBH, individual volume, stem straightness and trunk height of the seven provenances / families selected at 29 years old are 7.92%, 9.39%, 14.74%, 7.06% and 12.29%, respectively. Among them, provenance 8410 from Yunnan Longchuan Forest Farm and provenance 8603 from Hainan Jianfengling are more suitable for local growth.
Combined GEDI Data and Landsat 8 for Inversion of Forest Aboveground Biomass Based on Sequential Gaussian Condition Simulation
LUO Shao-long, SHU Qing-tai, YU Jin-ge, XU Li, YANG Zheng-dao
, Available online  , doi: 10.12403/j.1001-1498.20230450
Objective There are significant limitations in estimating forest biomass using a single remote sensing technology. The research aims to utilize the advantages of multi-source remote sensing collaboration technology to complement LiDAR and optical remote sensing, and to improve the accuracy of biomass estimation. Methods Based on the two main information sources, including spaceborne LiDAR GEDI and optical remote sensing Landsat8 data, Sequential Gaussian Conditional Simulation (SGCS) method was used to achieve spatial expansion of GEDI data from "points" to " polygons". Combing with aboveground biomass data of 138 plots, the random forest method was used to estimate the aboveground biomass of Picea asperata and Abies fabri forests in Shangri-La, Yunnan Province. Result (1) The SGCS method was used to perform spatial interpolation on GEDI footprints, and the simulated spatial distribution maps of 12 biophysical indicators showed random and fragmented characteristics, which were very similar to the spatial distribution and clustering of forests, and the OEC of 9 indexes involved in modeling were greater than 0.90. (2) The accuracy of the random forest model constructed using a single optical remote sensing Landsat8 data was: R2=0.82, RMSE=35.51 t·hm−2, P=0.77; The accuracy of the random forest model constructed by combining two types of remote sensing data was: R2=0.86, RMSE=32.11 t·hm−2, P=0.80. It could be obviously found that the accuracy of the model was improved. (3) The total aboveground biomass of Picea asperata and Abies fabri forests in Shangri-La in 2019 estimated by multi-source remote sensing technology was 37 042 605.68 t, and the average biomass was 123.28 t·hm−2. Conclusion The SGCS method based on geostatistics has some advantages, including considering the spatial heterogeneity of the research object and being able to overcome smoothingeffects I is feasible to achieve spatial expansion of GEDI footprints from "point" to " polygon ". The multi-source remote sensing data based on the combination of spaceborne LiDAR GEDI and optical remote sensing Landsat8 can effectively fill the defects of a single remote sensing data source, improve the estimation accuracy of forest biomass, and provide a reference for the combination of LiDAR and optical remote sensing to estimate large-scale and fully covered forest biomass.