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Seasonal Differences of Stemflow and Its Dependence upon DBH among Three Natural Forest Types in Funiu Mountain
NIU Bao-liang, LIU Yan-chun
, Available online  , doi: 10.12403/j.1001-1498.20230343
Abstract:
Objective The aim of this study is to determine the differences of stemflow between different forest types and its relationships with diameter at breast height (DBH), and analyze the seasonal variations in stemflow between forest types under the same rainfall levels. Method Field measurement including standard tree selection and stemflow collection was conducted in three typical forest types located at Baotianman of Funiu Mountain. Result During the growing season, stemflow volume was positively correlated with DBH under high-level rainfall, but negatively related to DBH under low-level rainfall. Stemflow volume (17770~35590 mL) and stemflow rate (0.106) were greater in winter than spring, summer and autumn under the same rainfall level. There were no differences in stemflow volume among three earlier seasons. Higher stemflow rate was found for conifers-broadleaf mixed forest in autumn and winter, which could be explained by the weakened interception of leaf at canopy in winter. The results showed that mixed coniferous-broadleaf forest had greater stemflow than that of coniferous and broadleaf forest mainly due to its higher stand density and lower DBH. Conclusion The finding that differential stemflow among forest types associated with rainfall levels and DBH values indicates that DBH and leaf property are critical to determine the seasonal variation in stemflow.
Characterization of Nutrient Stoichiometry Variability in Pleioblastus amarus Leaves from Different Subtropical Regions and Its Environmental Drivers
ZHANG Jing-run, ZUO Ke-yi, GUO Zi-wu, FAN Li-li, LIN Hua, HU Rui-cai, CHEN Shuang-lin
, Available online  , doi: 10.12403/j.1001-1498.20230364
Abstract:
Objective The study aimed to explore the impact of geographical differentiation on the stoichiometric characteristics of Pleioblastus amarus leaves and identify their primary environmental drivers. Method The C, N, P content, and stoichiometric ratio of P. amarus leaves from three different regions: Qianshan County, Anhui Province; Longyou County, Zhejiang Province; and Shaxian District, Fujian Province were explored. Pearson correlation analysis, LSD difference analysis, and structural equation modeling were employed to investigate the correlation between these characteristics and environmental factors. Result The results indicated that the contents of C, N, and P in P. amarus leaves decreased with increasing latitude, while the ratios of C∶N, C∶P, and N∶P showed an overall upward trend. Notably, P. amarus leaves from Qianshan County exhibited significantly lower concentrations of C, N, and P than those from Longyou County and Shaxian District. Moreover, the ratios of C∶N, C∶P, and N∶P were significantly smaller in Qianshan County than those in the other two regions. Additionally, the study found that as the age of the culms increased, the concentrations of C, N, and P decreased, while the ratios of C∶N and C∶P increased. There was no significant change observed in the N to P ratio with different ages. Pearson correlation analysis revealed that the annual mean temperature and soil chemical properties (such as total nitrogen, total phosphorus, total potassium, hydrolyzed nitrogen, available phosphorus, available potassium, organic matter, etc. ) significantly influenced the stoichiometric characteristics of P. amarus leaves. On the other hand, mean annual precipitation and soil physical properties had little effect on the stoichiometric characteristics of P. amarus leaves. The results of the structural equation model indicated a significant positive correlation between climatic factors, soil factors, and leaf stoichiometry characteristics, with similar effects. Conclusion This suggests that the variation in leaf stoichiometry due to geographical differentiation may be attributed to the combined effect of climate and soil factors. Among these factors, the annual average temperature, soil hydrolyzable nitrogen, soil total phosphorus, and soil available potassium are the main indicators affecting the stoichiometric variation of leaves.
Functional Diversity in Woody Plants of Different Growth Form in theTropical Rainforest of Xishuangbanna
CHEN Yan-xuan, HUANG Xiao-bo, LANG Xue-dong, TANG Rong, ZHANG Rui, LI Cong, LI Jun-song, LI You-shou, WANG Xiao-hai, SU Jian-rong, LI Shuai-feng
, Available online  , doi: 10.12403/j.1001-1498.20230385
Abstract:
Aims We analyzed the differences in functional traits of different growth forms of woody plants in a tropical rainforest of Xishuangbanna, and revealed the changing rules and influencing factors of functional diversity of woody plants with different growth forms. Methods Based on the survey data and the functional traits of woody plants from three 1 hm2 dynamic monitoring plots in Menglun, Bupung, and Shangyong in Xishuangbanna Nature Reserve, China, one-way variance analysis, principal component analysis, Pearson correlation analysis, redundancy analysis, and multiple linear regression analysis were used to analyze the changes and influencing factors of functional diversity among different growth forms of woody plants, and to discuss the functional characteristics and main influencing factors of woody plant communities in the tropical rainforest of Xishuangbanna. Results (1) The community weighted mean value of leaf area, leaf carbon content and leaf dry matter content of trees were significantly higher than those of shrubs and lianas, while the community weighted mean value of leaf nitrogen content and specific leaf area of lianas were significantly higher than those of trees and shrubs. (2) The functional richness and functional dispersion of trees were higher than those of shrubs and lianas, while the functional evenness and functional divergence of shrubs were higher than those of trees and lianas. (3) The functional richness of trees and lianas and the functional dispersion of lianas increased significantly with increasing plant species richness, abundance and phylogenetic diversity. The functional evenness and functional divergence of trees increased significantly with increasing of soil fertility, while the functional dispersion of shrubs increased with increasing plant species richness. (4) Abundance was the main factor affecting the community weighted mean value of functional traits of trees and shrubs, while phylogenetic diversity, plant species richness and soil fertility were the main factors affecting the community weighted mean value of functional traits of lianas. Conclusion This study reveals that functional traits and functional diversity have significant differences among different growth forms of woody plant communities in the tropical rainforest of Xishuangbanna. Moreover, woody plant abundance and soil fertility play a crucial role in maintaining the functional diversity of plant communities in a tropical rainforest in maintaining plant community functional diversity.
Seasonal Permafrost Degradation Characteristics in Southern Part of Greater Khingan Mountains under Climate Change
SUN Yi-chen, WEI Jiang-sheng, SHU Yang, ZHAO Peng-wu, QI Gui-ping, ZHANG Jing
, Available online  , doi: 10.12403/j.1001-1498.20230337
Abstract:
Objective Seasonal permafrost degradation directly changes water recharge at the beginning of the growing season, which in turn affects regional forest health. At present, the degradation of permafrost in Southern Part of Greater Khingan Mountains is still unclear, especially the degradation characteristics under climate change. Method : In the long-term experimental forest of Saihanwula National Nature Reserve in Inner Mongolia, environmental factors such as air temperature, soil temperature, and volumetric soil water content were observed from 2014—2022 to analyze the characteristics of permafrost degradation in forest seasons. Result : The temperature in Southern Part of Greater Khingan Mountains rose in shortly. The rise rate of annual average temperature was 0.42 ℃·(10 a)−1 in 1997—2022, which was larger 23.5% of the rate of 0.34 ℃·(10 a)−1 in 1973—1996, in Southern Part of Greater Khingan Mountains. It is particularly significant that the average temperature during the freeze-thaw period (i.e., November to June) rose faster with the rate of 0.46 ℃·(10 a)−1. The freeze-thaw pattern of soil was characterized by top-down unidirectional freezing and unidirectional melting; The freezing rate and thawing rate became faster with increasing soil depth, reaching a maximum in the 40~80 cm soil layer (freezing rate 2.23 cm·d−1, thawing rate 4.50 cm·d−1). Seasonally frozen soil continued to degrade, with the observed maximum freezing depth reduced from 80 cm to 40 cm. The freeze-thaw period was significantly shortened, the start of freezing was delayed, and the complete thaw time was advanced, resulting in a shortening of the annual freeze-thaw period by 15.21%. Applying the freeze-thaw multiple linear regression model established in this paper, the contribution of elevated air temperature accumulation to seasonal permafrost degradation in the study area was more than 90%. Conclusion : In the Southern Part of Greater Khingan Mountains, permafrost degradation is mainly characterized by shortening of the freeze-thaw period, and warmer temperatures are the main driver of seasonal permafrost degradation, making it necessary to monitor changes in seasonal permafrost in the future for better forest management.
Dynamics of Soil Microbial Groups in Pinus tabulaeformis Plantation in Response to Stand Structure Adjustment
FA Lei, PEI Shun-xiang, DU Man-yi, MA Shu-min, WU Sha, WU Di, WANG Hai-xia, LI Jia-lin, XU Ji-huang
, Available online  , doi: 10.12403/j.1001-1498.20230389
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Objective We explore the response mechanism of soil microbial community structure dynamics to the interference of stand structure adjustment in order to evaluate the impact of management treatment on the ecosystem of Pinus tabulaeformis Plantation. Methods Based on Pinus tabulaeformis plantations in Zhongtiao Mountain, Shanxi Province, we explored the group composition and diversity of soil microorganisms under the stand structure adjustment through the high-throughput sequencing technology to analyze the diversity、composition and structure of soil microbial community and its correlation with environmental factors. Results The results showed that stand structure adjustment could reduce the pH value of soil and the content of soil nutrients. The dominant flora of soil microorganisms did not change significantly. Proteus, actinomycetes and Acidobacteria were the dominant bacterial groups in the soil of Pinus tabulaeformis plantation, while the dominant fungal groups were Ascomycetes, Basidiomycetes and Mortierella. The richness of soil microorganisms in Pinus tabulaeformis plantation increased significantly after adjustment, but the difference was not significant in diversity. RDA analysis showed that pH, total nitrogen, soil organic matter and available nitrogen were the main factors driving changes in soil microbial community structure. Conclusion The treated Pinus tabulaeformis plantation is still in the disturbance recovery period. The microbial community structure is similar to that of the control treatment, but is more abundant in Pinus tabulaeformis plantation after stand structure adjustment, which improves the proportion of nitrogen fixing bacteria in the soil. The increase in Proteobacteria and Basidiomycota leads to soil microorganisms shift towards organic matter decomposition.
Characteristics of Woody Debris Biomass and Carbon Storage of Four Types of Tsuga longibracteata Communities
NI Shu-jing, XIAO Shi-hong, CAO Yan, LIANG Jing-wen, YOU Wei-bin, HE Dong-jin
, Available online  , doi: 10.12403/j.1001-1498.20230378
Abstract:
Objective This study aims to reveal the fundamental role of woody debris in the carbon cycle within the Tsuga longibracteata communities in Tianbaoyan National Nature Reserve (TNNR). The findings will provide a basis for the conservation and sustainable management of the Tsuga Longibracteata community. Methods Four forest types of Tsuga longibracteata communities in TNNR were investigated, including T. longibracteata pure forest, T. longibracteata + broadleaf mixed forest, T. longibracteata + Rhododendron simiarum mixed forest and T. longibracteata + Phyllostachys edulis mixed forest. The study conducted a dynamic investigation of different tree species and forms of woody debris (fine woody debris, log, snag, and stump) in the forest from 2012 to 2016. The biomass and carbon storage of woody debris were estimated, and their dynamic changes were analyzed. Results The results showed that: (1) Woody debris biomass accounted for the largest proportion (31.57%-77.77%) among the four population colonies and different tree species.; (2) The differences in the same form of woody debris types within the same forest type in different years were not significant in the four T. longibracteata communities (P>0.05). Log had the highest biomass in different years (T. longibracteata pure forest: 5.82-9.48 t·hm−2; T. longibracteata + broadleaf mixed forest: 10.90-17.83 t·hm−2; T. longibracteata + R. simiarum mixed forest: 7.20-10.37 t·hm−2; T. longibracteata + P. edulis mixed forest: 6.11-9.77 t·hm−2). There were significant differences in stump biomass between the T. longibracteata pure forest and the other three populations across the three surveys (P<0.05). (3) T. longibracteata communities had the largest carbon storage, which showed an overall growth trend with increasing year (T. longibracteata pure forest: 3.64-4.62 t·hm−2; T. longibracteata + broadleaf mixed forest: 4.67-4.71 t·hm−2; T. longibracteata + R. simiarum mixed forest: 2.29-2.53 t·hm−2; T. longibracteata + P. edulis mixed forest: 3.10-4.79 t·hm−2).; (4) Log had the highest carbon storage among the four types of T. longibracteata communities woody debris, except for T. longibracteata + P. edulis mixed forest. The carbon storage of log increased in the other three T. longibracteata communities. Among the four populations, the carbon storage of the T. longibracteata + broadleaf mixed forest was the highest, ranging from 4.91-7.68 t·hm−2. The carbon storage of snag significantly differed between the pure forest of T. longibracteata and the other three mixed forests (P<0.05). Conclusion Among the four T. longibracteata communities, log has the highest biomass and carbon storage among different forms of woody debris. Woody debris from different tree types has the highest biomass and carbon storage in T. longibracteata. The biomass and carbon storage of snag in the T. longibracteata pure forest are significantly different from those in other communities (P<0.05).
Effect of Continuous Planting on Archaeal Community Changes in Rhizosphere of Casuarina equisetifolia Plantations
ZHANG Qing-xu, LI Jian-juan, WANG Yu-hua, PENG Yan-hui, WANG Yan-yan, GUO Yue, HU Ming-yue, LIN Wen-xiong, WU Ze-yan
, Available online  , doi: 10.12403/j.1001-1498.20230339
Abstract:
Objective To investigate the impact of continuous planting on the changes in the archaeal community in the rhizosphere soil of Casuarina equisetifolia Forst. plantations for understanding of the obstacle mechanism of continuous planting of C. equisetifolia and providing a solid theoretical basis for further exploration. Methods We collected the rhizosphere soil from three C. equisetifolia plantations with varying generations of continuous planting (FCP, SCP, TCP). The rhizosphere soil from a natural arbor forest without C. equisetifolia was used as the control (CK). High-throughput sequencing of the archaeal community was performed using the Illumina NovaSeq sequencing platform. Results A total of 1 146 390 effective sequences were obtained from the rhizosphere soil samples and bare land control soil, resulting in the identification of 998 515 ASVs with 100% sequence similarity. The analysis of Alpha diversity indicated that the observed number of species and Chao1 index decreased with successive generations. However, the Shannon index, Simpson index, and Pielou_e were highest in FCP, followed by TCP, and lowest in SCP. The results of the Beta diversity analysis, Principal Coordinate Analysis (PCoA), UPGMA cluster analysis, and Anosim analysis indicated variations in the species diversity of the archaeal community in the rhizosphere soil of C. equisetifolia across different continuous planting generations. However, the differences between different groups were not significant. A total of 5 phyla were detected, and the dominant bacterial phylum was Thaumarchaeota and the proportion of Thaumarchaeota showed a decreasing trend with the increase of planting generations. Compared with the control, FCP, SCP and TCP decreased by 17.42%, 50.97% and 51.51% respectively. The results of the correlation analysis between archaea community and soil physical and chemical properties revealed significant positive correlations between Thaumarchaeota and pH, TK, TN and TP. Additionally, Crenarchaeota showed significant correlations with AP and AN. There were significant differences in the correlations between different archaeal communities and soil physical and chemical factors. Conclusion This study confirms that the archaeal community structure of the rhizosphere soil change significantly after multiple generations of continuous planting in C. equisetifolia plantations. It is speculated that the imbalance of the archaeal community structure is one of the key factors contributing to the imbalance of soil microecology. The study provides a theoretical foundation for understanding the causes of continuous planting obstacles in C. equisetifolia plantations.
Transcriptome Analysis of Populus in Response to Fusarium solani (Mart.) Sacc Inoculation
HAO Xin-yi, WANG Zhe-shu, FAN Zhi-bin, WANG Li-juan
, Available online  , doi: 10.12403/j.1001-1498.20230458
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Objective Based on RNA-sequencing, the differentially expressed genes, related signaling pathways and metabolic pathways in poplar responded to Fusarium solani (Mart.) Sacc inoculation were investigated, and the key genes involved in the interaction were screened. The present results will lay a foundation for further revealing the molecular mechanism underlying poplar resistance to F. solani (Mart.) Sacc. Methods The roots of 2-month-old seedlings of 84K were inoculated with 1 × 107 spores·mL−1 of F. solani (Mart.) Sacc spore solution. Zero-hour (control group), 48 h and 72 h (inoculated groups) after inoculation, root tissues were taken for transcriptome sequencing to explore genes related to poplar response to F. solani (Mart.) Sacc infection. Result (1) Compared with the control group, 8939 and 8246 DEGs (Differentially Expressed Genes) were detected in 48 h and 72 h inoculated samples, respectively. (2) GO analysis found that the differentially expressed genes were mainly enriched in single-organism process, response to stimulus, carbohydrate metabolism process, biological regulation and response to hormone. (3) KEGG pathway enrichment analysis showed that the DEGs were significantly enriched in glycolysis/gluconeogenesis, carbon metabolism, plant hormone signal transduction and phenylpropanoid biosynthesis. (4) The expressions of 21 genes in the SWEETs family of poplar were induced by F. solani (Mart.) Sacc. Ethylene receptor ETR, and the main components of the ethylene signaling pathway EIN3, ERF1, ERF2 were up-regulated. The expression levels of key enzyme genes involved in lignin synthesis including CCR, 4CL, C3’H and COMT were significantly increased. Conclusion Poplar may respond to the invasion of F. solani (Mart.) Sacc by regulating sugar metabolism and transport, activating the ethylene signaling pathway, promoting lignin accumulation, and thickening cell wall.
Decomposition Characteristics of Fresh Residues of Pleioblastus amarus in Different in-forest Environments
LIN Da-xue, ZHAO Hou-ben, HUANG Chun-hua, XU Wei-hua, LI Zhao-jia, Zhou Zhi-ping
, Available online  , doi: 10.12403/j.1001-1498.20230342
Abstract:
Objective To study the decomposition process of fresh residues of Pleioblastus amarus (Keng) keng and its influential factors, predict the changes in processes of ecosystem material cycling in bamboo forests after being mechanically damaged by extreme climatic events, and assess the impacts of the disaster on the function of forest carbon sinks for providing a basis for the scientific management of forests after the disaster. Methods Based on the secondary forests, where P. amarus expanded greatly after clearcutting, in the Nanling area of Guangdong Province, two treatments including removal of understory bamboos (RB) and control (CK) were set uo to generate distinct in-forest environments, and the decomposition characteristics of fresh residues from various organs of P. amarus were studied using the decomposition bag method. Results The decomposition process of fresh residues of each organ of P. amarus could be divided into two stages, rapid mass loss in the early stage (first 2 months) and slow decomposition in the later stage (last 24 months). The average mass loss rate of each organ in the early stage was in the order of leaves (51.2%) > twigs (31.7%) > roots (24.4%) > culms (16.6%), and there were significant differences (P<0.05) among all organs, with a significantly lower mass loss rate of leaves in RB environment than that of CK. The average mass loss rate of each organ at the later stage was in the order of twigs (40.3%) >leaves (29.1%) > culms (28.1%) > roots (19.6%), and there were significant differences among the organs except for leaf and culm. The mass loss rate of branches in RB environment was significantly higher than that of CK, while the mass loss rate of roots was significantly lower than that of CK. The Olson decomposition model could well fit the decomposition processes of various organs. The average decomposition coefficient (k) of leaves (0.891) was the largest, followed by the twigs (0.554), culms (0.249), and roots (0.242). There were significant differences of the k among all organs except for culms and roots, and the k of leaves in RB environment was significantly lower than that of CK. The period of 50% decomposition (T0.5) of each organ was in the order of culms (2.48 a) > root (2.44 a) > twigs (0.97 a) > leaves (0.51 a), with roots and culms significantly higher than twigs and leaves, and the T0.5 of root in RB environment was significantly higher than that of CK. The decomposition period (T0.95) of each organ was in the order of roots (12.81 a) > culms (12.12 a) > twigs (5.22 a) > leaves (3.22 a), with roots and culms significantly higher than twigs and bamboo leaves. Under RB environment, the T0.95 of culms and roots was significantly lower and higher than that of CK, respectively. The correlation coefficient between the substrate quality of various organ and decomposition indexes was generally higher in the early stage than in the later stage, and higher in the CK than in the RB environment. Among them, the correlation coefficients between carbon (C), potassium (K), C/nitrogen (N), C/phosphorus (P) and the decomposition indexes were relatively small; N, P, and N/P were positively correlated with decomposition rate, and lignin/N was negatively correlated with decomposition rate. Conclusion Decomposition of fresh residues of P. amarus is characterized by a rapid weight loss in the early stage and a slow decomposition in the later stage. Leaves have the fastest decomposition rate, followed by twigs and culms, and roots are the slowest. Among the substrate qualities of various organ, N, P, N/P, and lignin/N have significant impacts on the decomposition rate, in particular in the early stage of decomposition. Removal of understory bamboo can slow down the decomposition of leaves and roots, accelerate decomposition of culms and twigs, and attenuate the effects of substrate quality on decomposition rates.
Development of Stand Density Management Diagram for Carbon Storage Management for Masson Pine Plantations
LI Yu-hao, NIU Qing-yun, MENG Jing-hui
, Available online  , doi: 10.12403/j.1001-1498.20230489
Abstract:
Objective Masson pine (Pinus massoniana Lamb.) is an important plantation species in China. It not only provides essential economic benefits but also plays a crucial role in ecological services such as carbon sequestration, and adaption to climate change. Thinning is a vital technique in the management of plantations. However, the current practice of thinning in Masson pine plantations suffers from a qualitative rather than quantitative issue, which restricts the plantation management. This study aims to establish a density management diagram for Masson pine plantations to guide the precise thinning process. Method Based on the permanent plot of pure Masson pine plantations in Hunan Province, the basic density management diagram was constructed obeying to the Reineke rule. Subsequently, carbon storage contours was further imposed on the basic stand density management diagram to produce the carbon storage management diagram. Finally, using the management diagram, the stand density of Masson pine plantations in Cili County in Hunan Province was evaluated. Result In Cili County, Hunan Province, most of the stand density of Masson pine plantations were larger than the reasonable density range. This resulted in intense competition among trees for limited resources such as light, temperature, and moisture, and, in some stands, even severe natural mortality occurred. Thinning is urgently required to reduce stand density. A small number of stands were within the reasonable density range. These stands fully utilized natural resources with trees mutually promoting one another. Some stands had densities below the lower limit of the optimal range, resulting in inefficient utilization of forest land space and resource wastage. Understory planting is urgently needed. Conclusion The stand density management diagram for Masson pine trees developed in this study can accurately guide forest management practices. Furthermore, it can provide an assessment of the rationality of stand density for forest management enterprise.
Optimization and Application of Transient Transformation System of Larix kaempferi
XING Jun-xia, ZANG Qiao-lu, YE Zha-long, ZHANG Chen-yi, CHENG Dong-xia, QI Li-wang, YANG Ling, LI Wan-feng
, Available online  , doi: 10.12403/j.1001-1498.20230390
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Objective To optimize an Agrobacterium-mediated transient transformation system with Larix kaempferi embryogenic callus. Methods The embryogenic callus of Larix kaempferi cultured in liquid medium for 7 days was used as the receptor material, and pCAMBIA1305.1 vector carrying β-glucuronidase (GUS) was used for transient transformation. Based on the expression level and enzyme activity of GUS, the optimal infection solution concentration, infection time and co-culture time were screened. The activity of Larix kaempferi scarecrow-like 6 (LaSCL6) promoter was analyzed with the screened transformation system. Results After transient transformation, the expression of GUS was obvious. When the concentration of infection solution was 0.2, the infection lasted for 5 minutes, and the co-culture time was 72 hours, GUS expression was the highest, with -2.274 2. When the concentration of infection solution was 0.05, the infection lasted for 5 minutes, and the co-culture time was 72 hours, GUS enzyme activity was the highest with 25.728 6 U/L. The activity of LaSCL6 promoter was 1.55 times higher than that of CaMV35S promoter Conclusion In view of the expression level and enzyme activity of GUS, transformation efficiency is high when the concentration of infection solution is 0.05, the infection time is 5 minutes, and the co-culture time is 24 hours, which can be used for efficient transformation of embryogenic callus of Larix kaempferi.
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
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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
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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
Abstract:
: 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
Abstract:
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
Abstract:
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
Abstract:
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.