The R. roxburghii leaves were used as materials， and the triterpenoid chemical components were systematically isolated and purified from leaves by using methods of silica gel column chromatography， Sephadex LH-20 column chromatography， and semi HPLC， respectively. The structures of the compounds were identified through physicochemical properties and nuclear magnetic resonance spectroscopy （NMR） spectral data， and a total of 13 compounds were isolated and identified. Among them， there were two tetracyclic triterpenoid compounds， three pentacyclic triterpenoid glycosides， and eight pentacyclic triterpenoid carboxylic acid compounds， including a novel compound monomer. The structures identified were （1）β- sitosterol， （2）daucosterol， （3）2α，3α，19α-trihydroxyolean-12-en-28-O-β-D-glucopyranoside， （4）kaji-ichigoside F1， （5）rosamultin， （6）rosamultic acid， （7）new compound， （8）hyptadienic acid， （9）euscaphic acid， （10）tormentic acid， （11）corosolic acid， （12）betulinic acid， and （13）maslinic acid， respectively， and the compounds No.2， No.6， No.7 and No.8 were isolated and identified from this plant for the first time. This study clarified the triterpenoid components in R. roxburghii leaves， and provided scientific basis for the development and utilization of R. roxburghii leaf resources.
The objective of this study was to investigate the relationships between calcium uptake， organic acid metabolism and IAA during the development and ripening of Cerasus humilis fruit by treatment with exogenous plant growth regulator 2，4-D. The low-calcium C. humilis MY-9 fruit in Inner Mongolia was sprayed for 2，4-D at the young fruit stage and the coloring and swelling stage， and the effects on calcium uptake and organic acid metabolism and IAA during fruit development and maturity under 2，4-D treatment were studied with clean water treatment as control， and correlation analysis was carried out. The results showed that （1）In terms of calcium uptake rate， the uptake rate of pectin calcium， active calcium and total calcium was similar to that of the control， which increased first and then decreased， the uptake rate of the above three types of calcium from hard core stage to maturity stage was significantly higher than that of the control. On the contrary， the uptake rate of water-soluble calcium decreased first and then increased， and the value at late stage of fruit development was significantly higher than that of the control. In terms of calcium uptake activity， the changes of the four calcium forms were similar， showing a continuous decrease， and the calcium uptake activity of the treatment was significantly higher than that of the control. In terms of relative-growth calcium uptake， the changes of the four calcium forms were consistent， all of which increased first and then decreased， and the value of treatment at the hard-core and full-maturity stages was significantly higher than that of the control. （2）The activity of NAD-MDH， the amount of malic acid and organic acid increased with the development and maturity of fruits， and the activity of NADP-ME and citric acid decreased with the development and maturity of fruits， and the content of organic acids and related enzymes could be increased to varying degrees by 2，4-D treatment. （3）On the whole， the IAA content of the treatment and the control increased first and then decreased， and there were significant differences between the treatment and the control during the whole development period， and the 2，4-D treatment could significantly increase the IAA content of C. humilis fruit. （4）Correlation analysis showed that the uptake rate and relative-growth uptake rate of water-soluble calcium were significantly positively correlated with NAD-MDH activity， malic acid and organic acids contents， and negatively correlated with IAA content， NADP-ME activity and citric acid content. The uptake activities of pectin calcium， active calcium and total calcium were significantly positively correlated with IAA content， NADP-ME activity and citric acid content， and negatively correlated with NAD-MDH activity， malic acid and organic acids content. 2，4-D treatment increased the correlation between calcium uptake and citric acid content. In conclusion， 2，4-D treatment can increase the calcium uptake capacity， organic acid metabolism and IAA content in C. humilis fruit. With the enhancement of NAD-MDH activity， the contents of malic acid and organic acid increased， which would promote the uptake of water-soluble calcium， but decreased the uptake capacity of pectin calcium， active calcium and total calcium， while the increase of citric acid and IAA content would reduce the uptake of water-soluble calcium， and promote the uptake of pectin calcium， active calcium and total calcium. The 2，4-D treatment regulated the calcium uptake of fruits by increasing the metabolism of organic acids and the content of IAA.
Based on China Virtual Herbarium （CVH）， Plant Photo Bank of China （PPBC）， reports and contents description， combined with the actual distribution and various works in northern China， 109 invasive alien plants from 25 families， 64 genera（including 108 invasive alien plants from foreign sources and 1 invasive alien plant from domestic sources）were comprehensively and systematically sorted out in northern China for the first time. The composition， origin and distribution of 109 invasive alien plants in northern China were summarized， and their invasive route， time and damage mode were analyzed. The problems existed in the research and the management， the situation of invasive alien plants， and the related experiences and knowledge of invasive alien plants were discussed respectively.
Patterns of biomass allocation and stoichiometric characteristics offer significant insights into the expansion capacity and environmental adaptability of invasive plants. This study focused on the typical invasive plant Bidens alba L. in the riverbank area of Nanliu River， Guangxi. Based on the invasion coverage， five levels of invasion were categorized： minimal（≤15%）， mild（15% to 30%）， moderate（30% to 45%）， severe（45% to 60%）， and extremely severe（>60%）. The biomass allocation patterns， C∶N∶P stoichiometric characteristics， and the soil physicochemical properties of B. alba were comprehensively analyzed under different invasion levels， so as to explore and clarify the adaptation strategies and expansion mechanisms of B. alba. The results indicated that： （1）There was no significant difference in the biomass allocation of B. alba roots under different invasion levels（P>0.05）. Under severe and extremely severe invasions， the biomass allocation of stems significantly decreased（P<0.05）， while the biomass allocation of leaves significantly increased（P<0.05）. The average root-to-shoot ratio was not significantly different（P>0.05）. （2）As the level of invasion increased， the N and P contents in roots， stems， and leaves significantly increased（P<0.05）. The average N and P contents in leaves were 20.88 and 3.92 g?kg-1， respectively. （3）The C∶N and C∶P in roots， stems， and leaves significantly decreased with the increase of invasion levels（P<0.05）， while the change trend of N∶P was not significant. The average values of C∶N， C∶P and N∶P in the leaves were 21.06， 118.30 and 5.49， respectively. （4）The invasion levels of B. alba were significantly positively correlated with the N and P contents in roots， stems， and leaves， as well as the C， N and P contents in soil（P<0.05）. In summary， as the level of invasion increased， the resource allocation strategy of B. alba was optimized by increasing leaf biomass and leaf N and P contents， and soil C， N and P contents by interaction with soil to form a soil environment conducive to its rapid invasion.
Understanding the stability of the community and the ecological relationship between the main populations of the rare and endangered plant Picea neoveitchii community in the Bailong River Basin can provide a theoretical basis for the protection and restoration of the endangered species P. neoveitchii. Based on the community investigation， the niche characteristics and community stability of 19 main populations of P. neoveitchii community in Bailong River Basin were analyzed by using Levins niche width， Pianka niche overlap index and M. Codron stability. The results showed that ： （1）P. neoveitchii and Cotinus coggygria var. pubescens were the absolute dominant species of the community， occupying the maximum niche width in different layers. They made full use of environmental resources and adapted to the changes of different environments in the field environment with limited resources. （2）There was a high degree of niche overlap within the community， and the degree of niche differentiation was not high， the demand of various populations for environmental resources showed a high degree of consistency， and the potential interspecies competition was strong. （3）The stability of the whole community and each vertical layer was far away from 20/80， which was in an unstable state. The research suggested that P. neoveitchii had a dominant position and strong competitive advantage in the whole community. However， the degree of niche differentiation within the community was not obvious， the potential competition among populations was fierce， and the structure of the community was extremely unstable. Insufficient resources and strong interspecies competition might be one of the reasons for its endangerment.
In order to analyze the competitive relationships among the three hardwood tree species in northeast China， a sample plot of secondary broad-leaved mixed forest with an area of 1 hm2 was set in Heilongjiang Grand Canyon National Nature Reserve. The DBH greater than 5 cm， species， and coordinates of all trees in the sample plot were measured， and the competition intensity was calculated by Hegyi competition index algorithm to examine the relationship between the competition intensity and DBH of three tree species. It provides strong support for the protection of three hardwood tree species in northeast China. The results showed that in the competition between the subject trees and competing trees， the intraspecific， interspecific and average competition intensity of the tree species decreased with the increase of DBH， and the competition intensity was positively correlated with the number of subject trees. The intraspecific competition index， interspecific competition index and total competition index increased with the increase of the number of subject trees. In the competition of the three hardwood tree species， except for the Fraxinus mandshurica， Juglans mandshurica and Phellodendron amurense were the most intense intraspecific competition， and the relationships between the DBH of the subject trees and the competition indexes （intraspecific， interspecific and total） were the power function relationship.
To investigate the spatial structure， distribution pattern， and seedling regeneration of Taxus cuspidata populations， the T. cuspidata community in the Muling National Nature Reserve was used as materials， and a standard plot of 300 m×400 m was established， and individual trees were investigated for their species name， growth and spatial position. Spatial structure parameters such as uniform angle index， neighborhood comparison， and mingling degree were calculated. The spatial structure， distribution pattern， and interspecies relationship curves of T. cuspidata populations were analyzed. Four regeneration count models including Poisson， negative binomial， zero-inflated Poisson， and Hurdle-Poisson were further established and compared for the regeneration of T. cuspidata seedlings. The results indicated that： （1）the spatial structure unit of T. cuspidata populations primarily exhibited random distribution， high mingling degree， and high uniformity index， with a relative frequency of 0.619 6； （2）the population demonstrated an aggregated distribution at a scale of 0-100 m； （3）a positive correlation was observed for T. cuspidata populations at a scale of 0-150 m， and seedlings showed varying correlations with their maternal trees across different scales， while correlations with other dominant species were relatively low； （4）T. cuspidata seedlings exhibited an aggregated distribution at a scale of 0-25 m， with an optimal regeneration count model being the Negative Binomial model.
The fixed monitoring plot was conducted in the Xilinhe National Nature Reserve to analyze tree species diversity， dominant species niche， interspecific associations and community stability in the Piceakoraiensis-Abies nephrolepis-Pinus koraiensis forest community by using a series of analysis methods including the α diversity index， the niche determination， the variance ratio（VR）， the Chi-square test（χ2 test）， the Spearman’s rank correlation coefficient test and the M. Godron stability. The results showed that： （1）the plot encompassed 20 tree species， 14 families and 14 genera， with a balanced distribution of trees， and the α diversity index was high； （2）the community niche overlap index was relatively high， but the cases with large （>0.7） or small（<0.4） niche overlap index were rare with a moderate degree of niche differentiation； （3）the overall correlation of the community was nonsignificant positive， and the interspecific correlations among the main tree species were mainly positive and nonsignificant correlation with strong interspecific independence； （4）the stability of M. Godron analysis fell to the point（32.79， 67.21） and was far from the stable point （20， 80）， indicating poor community stability； （5）P. koraiensis had the highest importance value and niche width in the sample plot， the average niche overlap index with other tree species was higher than the average value of the sample plot； the species was dominated by large-diameter individuals， and the relative frequency among tree species was low. Therefore， during the restoration process of Piceakoraiensis-Abies nephrolepis-Pinus koraiensis forest， the appropriate artificial intervention should be carried out to promote the recovery of Pinus koraiensis population， to regulate interspecies relationships， to enhance interspecies association strength， and to strengthen monitoring and protection of rare plant populations when community stability declined.
To complement and improve the community composition and structural characteristics of the summit mossy dwarf forests in Southwest China， based on the community survey data of the 1 hm2 forest dynamic plot（FDP）， the Center for Tropic Forest Sciences（CTFS） standard was used to investigate all woody trees with DBH ≥ 1 cm in the plot. Then， ten standard plots（a total of 0.6 hm2， 20 m×30 m each） were selected from the 1 hm2 FDP， and all vascular plants within the 0.6 hm2 plot were investigated and counted by plant community inventory. The species composition and community structure were analyzed by the aspects of species richness and quantitative characters， and the diameter class structure of the dominant tree species. The main results were as follows： （1）there were 3 614 woody individuals from 42 species， 32 genera， 20 families， with DBH≥1 cm within the 1 hm2 FDP； in the 0.6 hm2 plot， there were 103 species of vascular plants in 42 families， 67 genera and 1 536 individuals of 24 woody species with height≥3 m； （2）Rhododendron sinofalconeri was， absolutely dominant in the community， with important values 3-4 times higher than those of the secondary dominant species； （3）The age structure of the whole community showed a “L” shape； however， Rhododendron sinofalconeri was dominant in adult individuals， being different from other dominant species； （4）The community was composed of tree， shrub and herb layers as well as epiphytes and parasitic plants， and named as Rhododendron sinofalconeri， Clethra delavayi var. yuiana， Illicium tsaii summit mossy dwarf forests. In the Bozhu Mountain， Wenshan county， Yunnan， China， the mossy dwarf forest community was rich in species， stable in composition， prominent in dominant species and good in their regeneration. The canopy appearance of the community was flat， and the community succession was in a mature forest state.
Exploring the coupling relationship among stand structure， site conditions， protection intensity， and plant diversity is helpful to improve the effect of plant diversity protection in protected areas. Based on this， the forest community of the Chuona River National Nature Reserve in Daxing’anling Mts was selected as the research object， the plant diversity and stand structure characteristics of the arbor， shrub， and herb layers were investigated， and the soil samples were collected and the soil physicochemical properties were determined. The frequency distribution， redundancy ranking and variance analysis were used to reveal the characteristics of plant diversity and its coupling relationship with influencing factors. The results showed that：（1）Larix gmelinii was the dominant tree species in the tree layer of Chuona River Reserve， with a relative abundance of 64.35%， followed by Betula platyphylla. The proportion of lingonberry（Vaccinium vitis-idaea） in shrubs was the highest， reaching 72.70%. A total of 77 herbs were recorded， of which Carex callitrichos accounted for the largest proportion（23.72%）. （2）The order of richness index and diversity index was herb layer>arbor layer>shrub layer， and the shrub layer had the highest evenness index. （3）Redundancy analysis and variance decomposition analysis showed that the independent effects of stand structure explained the most changes in plant diversity. Herbaceous coverage， shrub density， tree height and soil bulk density were most closely related to plant diversity changes. Adjusting stand structure would be a simple and reliable way to improve plant diversity， and the above results provided data support for stand management in Daxing’anling Mts.
To address the problem of the rooting ability of Fraxinus mandshurica cuttings significantly decreasing after three years due to age effect， four-year-old F. mandshurica seedlings were used to investigate the role of cycle rejuvenation through cuttings in overcoming age effect in this study. The impact of the number of cycles and topping treatment on the sprouting， growth， and rooting of F. mandshurica cuttings， as well as the physiological changes during its rejuvenation process were examined. The results showed that the measurement of increasing the number of rejuvenation cycles and topping treatment both enhanced the degree of rejuvenation in F. mandshurica， which were characterized by an increased number of sprouted branches， finer branches， and shorter internodes， while significantly improved the regeneration ability of the cuttings. When the number of rejuvenation cycles reached three and was combined with topping treatment， the number of sprouted branches increased by 6.56 times， and the rooting rate increased by 7.44 times compared to non-rejuvenated treatment. During one to three rejuvenation cycles， the indole acetic acid（IAA） and cytokinin（CTK） levels in the plants increased， the gibberellin（GA3） levels significantly increased only at the third cycle， and the abscisic acid （ABA） levels decreased gradually. After rejuvenation， the activities of catalase（CAT）， peroxidase（POD）， and superoxide dismutase（SOD） and the contents of malondialdehyde（MDA） and soluble sugars decreased in the regenerated plants. These physiological changes were consistent with the juvenile state of the plants. Cycle rejuvenation can effectively restore the juvenile state， induce the formation of sprouts with higher IAA and GA3 levels and lower ABA levels， and simultaneously reduce the oxidative state and soluble sugar content in F. mandshurica. These changes are beneficial for achieving rejuvenation of F. mandshurica， thereby increasing the rooting rate of F. mandshurica cuttings and enabling rapid and efficient clonal propagation of superior F. mandshurica varieties.
Seeds of 18 F. mandshurica clones were used as materials， the germination performances of clones at suitable temperatures after different stratification treatments were compared， and the relationships between germination performances and seed embryo growth changes were analyzed. The results showed that the germination performances of seeds were different among F. mandshurica clones after different stratification treatments. Seed dormancy of clones 1， 2 and 6 was shallow and could be broken after variable temperature stratification treatments for a short time（a total 18 weeks）， which the germination rate of clones 2 and 6 reached more than 75%. Seed dormancy of clones 13， 14， 15 and 16 were broken by 20-week stratification treatment （cold temperature extended for two weeks）， and clones 4， 8， 11 and 12 by 20-week stratification treatment （warm temperature extended for two weeks）. Seeds dormancy of clones 5 and 18 was deep-degree， it could be broken by extending the stratification（warm and cold temperature） time to 22 weeks. Seed dormancy of clones 3， 7， 9， 10 and 17 could be broken by stratification treatment for 20 weeks， without significant difference in the dormancy between seeds treated by extending warm and cold stratification time. The changes of embryo length， embryo rate and embryo mass ratio in the process of stratification were different in different clones， and relative extension time（two weeks） of cold temperature stratification in clones 6， 7 and 11 was conducive to embryo growth， and extension time（two weeks） of warm temperature stratification in clones 2， 5 and 17 was conducive to embryo growth. Differences in seed dormancy of different clones could not be accurately judged by changes in seed embryo growth during the stratification process， which should be judged mainly by the germination performances. The results could provide a reference for the selection of mother clones with shallow seed dormancy in production practice.
In order to reveal the mechanism of selenium alleviating the cadmium stress in Astragalus membranaceus， the traditional medicinal plant A. membranaceus was used as materials， and the roles of ion antagonism， antioxidant enzyme system， heavy metal chelates and isoflavones in alleviating the Cd stress by Se were clarified comprehensively using hydroponic cultivation method. The results showed that 10 μmol·L-1 Se significantly improved the growth of A. membranaceus seedlings under 50 μmol·L-1 Cd stress， and reduced the accumulation of reactive oxygen species and membrane lipid peroxidation levels. The addition of Se significantly reduced the Cd content in all parts of A. membranaceus under Cd treatment. Meanwhile， the addition of Cd also reduced the Se content， indicating that it has a significant antagonistic effect on the absorption of Se and Cd. Se reduced the activities of POD， SOD， APX， CAT and GR in all parts of A. membranaceus under Cd stress. Correlation analysis showed that various antioxidant enzymes activities were significantly positively correlated with O 2 ? - content， suggesting that the changes of antioxidant enzyme activity were more adapted to the level of reactive oxygen species in the plants. In addition， the addition of Se also reduced the content of non-protein sulfhydryl groups and metallothionein in all parts of A. membranaceus exposed to Cd treatment， and the contents showed a good positive correlation with the Cd content in corresponding part， indicating that the content of heavy metal chelates was regulated by the Cd content in various parts. Unlike antioxidant enzymes and metallothionein， the contents of three isoflavone components were significantly increased by Se addition in the roots of A. membranaceus seedlings under Cd stress. Furthermore， the expression levels of key enzyme genes in the isoflavone synthesis pathway， including CHS， IFS， I3'H， IOMT and UCGT， were significantly upregulated by Se under Cd stress. In summary， Se decreased the content of Cd in A. membranaceus seedlings under Cd treatment by antagonizing Cd during the absorption process， and reduced the degree of plant stress. At the same time， Se improved the tolerance of plant to Cd stress by upregulating the synthesis of secondary metabolites such as isoflavones.
To investigate the dormancy type and physiological and metabolic characteristics of Acanthopanax senticosus seeds during germination， the seeds from northeast China were treated with sand accumulation for 140 days under different temperature conditions（20 ℃， 4 ℃， 20 ℃/4 ℃） respectively. Five distinct stages were identified based on embryo phenotypic changes，and the dynamic changes in endogenous hormones， main nutrient substances and their hydrolases， antioxidant system， and metabolomics during these five stages were examined respectively. The results revealed that： （1）A. senticosus seeds exhibited good water absorption； while the constant temperature of 20 ℃ only promoted embryo elongation， but not germination. There was no increase in embryo rate at 4 ℃， and the embryo rate increased and the seeds germinated only when the temperature was maintained at 20 ℃ for 0-110 d and 4 ℃ for 110-140 d. （2）As the embryo growth rate increased， gibberellic acid content increased while abscisic acid content decreased. The levels of indoleacetic acid， indolebutyric acid， and naphthenic acetic acid all decreased. Fat content decreased while soluble sugar content increased. Fat content showed a significant negative correlation with lipohydrolase activity as well as a highly significant negative correlation with soluble sugar content. （3）A total of 92 differential metabolites were screened， and the carbon metabolism， energy metabolism， and antioxidant metabolism were the major differential metabolic pathways. Additionally， there were difference in sesquiterpene and triterpene biosynthesis， fatty acid biosynthesis and glyceride metabolism. In conclusion， seeds of A. senticosus were morphological and physiological dormancy， and variable temperature stratification was a necessary condition to break seed dormancy， and endogenous hormones might regulate seed dormancy and germination. Macromolecular nutrients such as fat were decomposed by hydrolases to provide material and energy for seed germination， which was also one of the necessary conditions for seed germination. This study provided theoretical guidance for identifying seed dormancy types and artificial propagation of A. senticosus.
Based on the fact that soil microorganisms can enhance the adaptability of plants to global change， the effects of soil microorganisms on the ecological stoichiometric characteristics of rhizosphere soil microorganisms were studied under the background of nitrogen deposition， and then the regulation of changes in ecological stoichiometric characteristics on the soil microbial nutrient limitation was explored. Under the premise of soil sterilization treatment（sterilized soil（+S） and non-sterilized soil（-S））， one-year-old potted seedlings of Caragana korshinskii were inoculated in two ways（inoculation（+M） and without inoculation（-M））， and nitrogen addition treatments（no nitrogen application（CK）， low nitrogen（LN， 3 g·m-2·a-1）， high nitrogen（HN， 6 g·m-2·a-1）） were set up. Compared with the original microbial community composition in non-sterilized soil without fungus inoculation， the correlation between ecological stoichiometric characteristics of microhabitat and microbial nutrient limitation under different treatments was explored.Results were as follows： （1）In sterilized soil treatment， the relative abundance of fungi in the rhizosphere soil of C. korshinskii mycorrhizal seedlings was significantly increased by 82.20%， 25.00% and 59.84% under CK， LN and HN treatments than that of non-mycorrhizal seedlings， respectively. （2）In the treatment of non-sterilized soil， the microbial biomass carbon-to-phosphorus ratio in the rhizosphere soil of non-mycorrhizal C. korshinskii seedlings under LN treatment was lower by 46.28% compared to CK treatment（P<0.05）， while that of mycorrhizal seedlings was 56.76% higher compared to CK treatment（P<0.05）. （3）Under the nitrogen addition treatments， stoichiometry of carbon and nitrogen-related soil enzyme activity， stoichiometry of carbon and phosphorus-related soil enzyme activity， and vector length in the rhizosphere soil of C. korshinskii non-mycorrhizal seedlings under sterilized soil treatment were significantly lower than those of mycorrhizal seedlings（P<0.05）. （4）PLS-PM path analysis showed that the total effect coefficient of microbial regulation on microbial nutrient limitation was greater than that of nitrogen addition treatment. In summary， soil indigenous microorganisms and mycorrhizal fungi synergistically regulated the enzymatic stoichiometric ratio of rhizosphere soil， and enhanced the adaptation of soil microbial nutrient limitation to nitrogen addition.
To provide a theoretical basis for the timely harvesting of Aralia elata， the cultivated A.elata was used as experimental materials， and the biomass， photosynthetic pigment content， total phenolic content， total flavonoid content， and antioxidant capacity of A. elata leaves in different harvesting periods（S1 period， April 10th， 2023； S2 period， April 30th， 2023； S3 period， May 20th， 2023； S4 period， June 9th， 2023） were analyzed respectively. Meanwhile， the high-performance liquid chromatographic（HPLC） method was established to determine the contents of araloside X， araloside V， and araloside A. Based on high-performance liquid chromatography-mass spectrometry metabolomics technology， the differences in secondary metabolites of A. elata at different harvesting periods were compared and analyzed. The results showed that： （1）The fresh weight， dry weight， and photosynthetic pigment content of A. elata leaves increased with growth， and reached the maximum value in the S4 period. （2）The contents of total phenol and total flavone reached the maximum value in the S1 period（1.36 mg·g-1， 29.38 mg·g-1）. （3）The scavenging ability of DPPH radical was the strongest in the S1 period（IC50 of 0.262 g·L-1） and the scavenging ability of ABTS radical was the strongest in the S2 period （IC50 of 0.511 g·L-1）. （4）The content of araloside A reached a maximum of 12.90 mg·g-1 in the S4 period. The contents of araloside V and X in the S2 period were significantly higher than those in other periods， which were 1.53 and 3.30 mg·g-1 respectively. （5）A total of 24 phenolic metabolites were identified， and the total amount of phenolic compounds in the four periods were 64.84， 119.31， 101.95 and 89.32 mg·g-1， respectively. Among the total phenolic compounds， the C6C1 backbone compounds （protocatechuic acid and gentisic acid）， the C6C3C6 backbone compounds （rutin）， and the C6C3 backbone compounds （caffeic acid） were significantly accumulated in the S2 period. In conclusion， considering the content of functional components， antioxidant activity， and edibility， the S2 period is the most suitable time for harvesting.
The establishment of shelter forests in the northeastern region of Ulan Buh Desert is a crucial ecological barrier to protect agricultural productivity within the eastern Hetao Plain. However， the lack of attention towards scientific research on artificial afforestation has resulted in a decline tendency in many shelter forest systems. The investigation of ecological adaptability of indigenous tree species after artificial cultivation was a crucial approach to guide the establishment and sustainable management of plantations. In order to further investigate the ecological adaptability of native tree species in Ulan Buh Desert after artificial cultivation， three native tree species： Ammopiptathus mongolicus， Zygophyllum xanthoxylon and Prunus mongolica were used as materials. By measuring the epidermal morphology， anatomical structure， and physiological indices of functional leaves， in conjunction with local meteorological data， the adaptive mechanisms of these plants to arid desert environments were clarified. The results showed that each of three plants exhibited distinct adaptations to arid desert environment in different ways. A. mongolicus enhanced light exposure and photosynthetic efficiency by augmenting leaf area， strengthened leaf mechanical defenses through dense epidermal hairs and well-developed cuticle， reduced light-induced damage and water transpiration， and maintained cellular water balance to minimize lipid peroxidation. The leaves of P. mongolica were clustered， by increasing number of leaves， the light receiving area was increased and the photosynthetic efficiency was improved， and by curling the leaves to avoid strong light burns， the water transpiration was reduced and the cell water balance was maintained by specializing the stomatal position（all the stomata were distributed on the lower surface of the leaves）， developed vascular bundles and rich mucous cells and crystal structures， and reduced cell membrane lipid peroxidation. The leaves of Z. xanthoxylon showed a cylindrical strip structure. By reducing the wind resistance， the probability of wind-sand flow damage to the leaves was reduced. The antioxidant enzyme activity and osmotic adjustment substance content in leaves was enhanced by physiological metabolic regulation， and the balance of cell water and reactive oxygen species metabolism was maintained. These findings suggested the different adaptation strategies adopted by the three plants in response to the desert environment， and provided the new ideas for introduction and domestication of native tree species in the northeastern Ulan Buh Desert.
In order to reveal the characteristics of fine root（diameter ≤2 mm） morphology and vertical distribution of biomass from different provenances and families of 24-year-old Picea koraiensis， the soil core method was used to determine fine root morphology and biomass at different soil layers（surface layer： 0<h≤ 10 cm， subsurface layer： 10 cm<h≤20 cm， bottom layer： 20 cm<h≤30 cm） in 30 families from four provenances（Muling， Linkou， Jinshantun， and Wuyiling from low to high latitude） in Qingshan Forest Farm， Linkou County， Heilongjiang Province， China. The results showed that there were significant differences in all fine root morphological traits among different provenances， and specific root length and root tissue density exhibited significant differences among families within provenance. At the provenance level， the average root diameter of Wuyiling provenance was the thickest at all soil layers， whereas specific root length and root tissue density of Linkou provenance were the largest. At the family level， in 0<h≤10 cm soil layer， root diameter of W035 was the thickest， that of CK-2 was the thinnest， specific root length of CK-2 was the longest， that of W043 was the shortest， root tissue density of J082 was the highest， that of M515 was the lowest. Root tissue density and specific root length of different provenances and families of P. koraiensis decreased with the increase of soil layer， while root diameter increased. The total fine root biomass（all three soil layers） across the four provenances was 33.56 g·m-2 on average， with the maximum occurring in Linkou provenance （39.04 g·m-2） and the minimum in Jinshantun provenance（32.52 g·m-2）， showing inconsecutive geographical distribution. Fine root biomass decreased with soil layer increasing， and root biomass at the surface soil layer accounted for 77% of the total biomass on average. In comparison， the low-latitude provenance of Muling tended to distribute greater fine root biomass at the subsurface and bottom soil layers， while the high-latitude provenances of Wuyiling and Jinshantun had higher fine root biomass at the surface soil layer， indicating that P. koraiensis originated from cold site tended to allocate more fine roots at the fertile surface soil.
Alpine meadows exhibited environmental characteristics such as intense radiation， low air pressure， strong winds and sudden changes in diurnal temperature， which were unfavorable for plant growth. In order to explore the ecological adaptability of Cynanchum forrestii， an endemic species of China to the alpine meadow environment（altitudes of 3 100-3 500 m） in Jiulong County， southwest Sichuan Province， the anatomical features of various organs of C. forrestii were examined by optical microscopy and scanning electron microscopy， and the pollen and seed viability were analyzed by the TCC method. The results showed that the leaves， stems and flowers of C. forrestii were covered with epidermis composed of rich single-row cells； the cuticle of leaf and stems epidermis was thick； the stomata were large and located on the lower surface of the leaves， palisade tissue and sponge tissue were developed； the stem epidermal cells were small and the cell wall was thick， and the cortex was composed of seven layers of cells， which were closely arranged， there were rich substances stored in the stem cells， and the vascular columns accounted for a large proportion of stem， the pith was developed and rich in stored substances； the root vascular tissue was well-developed， rich storage substances in cortical cells； the characteristics of high seed and pollen vitality， combined corolla， combined pistil column， the seed had seed hair， and thick and hard seed coat provide guaranteed for improving reproductive efficiency. The above results indicated that C. forrestii possessed a comprehensive array of external and internal structural characteristics， which enabled adaption to high-altitude cold environments while maintaining elevated levels of radiation resistance， drought resistance， and cold tolerance， and laid a structural foundation for the successful survival and reproduction of C. forrestii in the alpine environment.
In order to explore the obstacle factors of regeneration of Amygdalus ledebouriana in Xinjiang， and to better protect the germplasm resources and population， the seeds of A. ledebouriana in Barluk Mountain of Xinjiang were used as experimental materials， and the effects of seed water absorption characteristics， different stacking time， different concentrations of GA3 and different substrate treatments on the dormancy and germination characteristics of A. ledebouriana seeds and the germination inhibitors in A. ledebouriana were explored respectively. The results showed that： （1）The natural dormancy of whole seeds was relieved after 80 days stratification， while the decorticated seeds could germinate without stratification， and the addition of 300 mg·L-1 GA3 could break the dormancy of decorticated seeds in advance and improve the germination rate. （2）The germination inhibitors in A. ledebouriana seeds mainly existed in exocarp and mesocarp. （3）The germination rate of A. ledebouriana seeds in the original habitat soil was higher than that in the nutrient soil.
