In order to promote the rapid greening of the steep bare rock slopes in the Jiuzhaigou National Nature Reserve after the earthquake， and accelerate the ecological restoration process of the landscape， based on references and field investigations， 30 common native mosses in the region were selected， and an evaluation index system of 18 items was constructed based on six aspects including resistance ability， availability， ecological function， reproductive ability， biomass accumulation， and aesthetic appeal， using the Analytic Hierarchy Process（AHP）. The results indicated that： according to the comprehensive evaluation score， the mosses were divided into four grades. Finally， five species， Racomitrium japonicum， Hypnum plumaeforme， Eurohypnum leptothollum， Plagiomnium ellipticum and Brachythecium rutabulum were selected. The results should provide an objective guidance for future ecological restoration without soil in Jiuzhaigou and its surrounding cold fragile ecosystem area.
To provide an effective supplement for ecological restoration technology in the Arsenic sandstone area， the microecological soil environment in Pinus tabulaeformis and Caragana korshinskii plantation， naturally restored grassland， and abandoned land were studied respectively. The changes in microbial community structure and microbial biomass carbon， nitrogen and phosphorus contents， soil enzyme activities related to nutrient conversion， and soil chemical properties were analyzed in different vegetation types. The correlation between soil microbial community structure and soil microecological environment was discussed， then the main influencing factors of soil microhabitat types were explored in different ecological restoration vegetation. The results showed that： （1）The soil dissolved organic carbon（C） content of P. tabulaeformis plantation was the highest of the four vegetation types， which was 4.26 mg·kg-1. The soil available nitrogen（N） content of the C. korshinskii plantation was the highest， which was 11.69 mg·kg-1. However， there was no significant difference in soil available phosphorus（P） content among P. tabulaeformis plantation， C. korshinskii plantation and natural restored grassland. （2）The enzyme activities related to nutrient conversion and soil microbial biomass C， N and P of P. tabulaeformis plantation were significantly higher than those of other vegetation types. （3）The relative abundance of soil fungi was the highest in P. tabulaeformis plantation， which was 31.36%. The relative abundance of Gram-positive bacteria in the soil of the C. korshinskii plantation and abandoned land was the highest， which were 35.73% and 37.27%. The relative abundance of soil Gram-negative bacteria increased with the decrease of available organic C. It was the lowest in P. tabulaeformis plantation（36.82%） and the highest in the natural restored grassland（42.13%）. （4）The relative abundance of soil fungi was positively correlated with enzyme activities related to nutrient conversion. Gram-negative bacteria of preferred unstable C sources were less correlated with soil microecological environmental factors. Still， Gram-positive bacteria were significantly negatively correlated with the indexes of soil C conversion. （5）The Redundancy analysis showed that alkaline phosphatase was the most explainable environmental factor， and it was positively correlated with fungi and negatively correlated with Gram-positive bacteria（P<0.01）. In conclusion， the stability of the microecological environment of P. tabulaeformis plantation was relatively high in the ecological restoration vegetation types of the Arsenic sandstone area， which might be used as the optimal ecological restoration tree species in the Arsenic sandstone area. The synergistic effect of alkaline phosphatase and fungi in rhizosphere soil microecological environment might effectively regulate environmental restoration in Arsenic sandstone areas.
To explore the leaf color mechanism of Acer negundo ‘Aurea’， and to provide theoretical basis for the leaf color mechanism and cultivation of golden leaf plants， the golden re-green and green leaves of A. negundo ‘Aurea’ were used as materials， the leaf color parameters， pigment content and anatomy structure of three leaf types were measured and compared. The results showed that the leaf color parameters L*， a*， b* of the golden leaves were significantly higher than re-green leaves and CK（P<0.01）. The leaf color parameters of A. negundo ‘Aurea’ showed a downward trend during the process of re-greening. The chlorophyll a， chlorophyll b， total chlorophyll and， carotenoid content of the golden leaves were significantly lower than re-green leaves and CK， ω（carotenoid）/ω（total chlorophyll） was 0.64， which was significantly higher than re-green leaves and CK（P<0.01）， and pigment content of the golden leaves increased during the process of re-green. The cross-section structure of the three types leaves were different in the thickness， the ratio and arrangement of tissue. The thickness of golden leaves was 124.51 μm， which was significantly lower than that of CK（P<0.05）. The palisade tissue thickness of 31.26 μm and the palisade/spongy ratio of 0.45 in the golden leaves were significantly lower than other two types of leaves（P<0.01）， the palisade tissue and spongy tissue were arranged irregularly and disorderly， while the other two leaf types were arranged regularly and orderly； The chloroplast length and width were 3.42 μm and 1.27 μm respectively， which were significantly smaller than the re-green leaves and CK（P<0.01）， the chloroplast volume was small and incomplete， lacking thylakoid stacks. The high ω（carotenoid）/ω（total chlorophyll）， thinner palisade tissue， lower palisade/spongy ratio and lack of stacking of thylakoid in chloroplasts were the reasons for the golden color leaves of A. negundo ‘Aurea’.
Abies beshanzuensis is a critically endangered plant endemic species in Baishanzu Mountain， Zhejiang Province， and only three mother trees are remained， one is scattered， and the other two grow adjacent to the north and south. In order to understand the spatial-temporal pattern of the seed rain of A. beshanzuensis， 33 seed collection frames were set up to collect the seeds produced in 2017 and 2019 once every half month. The results showed that： （1）From December 16th， 2017 to February 28th， 2018， 1 093 seeds from the scattered tree and 1 020 seeds from two adjacent trees were collected using six times， while from November 31th， 2019 to January 16th， 2020， 341 seeds from scattered tree and 165 seeds from the adjacent north tree were collected using four times. （2）The fresh weight of 1 000 seeds of A. beshanzuensis varied greatly， with the minimum of two adjacent trees seeds in 2017（25.87 g） and the maximum of the adjacent north tree seeds in 2019（39.21 g）. The maximum length， width and thickness of the seeds were 14.5， 6.8 and 4.1 mm respectively， and the maximum length and width of the seed wings were 16.4 and 13.7 mm respectively. Both seed plumpness rate and 1 000-seed mass showed a trend of “decreasing first and then increasing”. The seed wing， seed plumpness， and seed fresh weight were larger in the north direction， whereas those in the south direction were smaller. There was no obvious pattern between seed characters and the distance from the collection frames. （3）In 2017， there were two peaks of seed rain， and the seeds collected in the first two times were about 80% of the total. However， in 2019， there was only one peak of seed rain， and the seeds collected for the first time were about 80% of the total. After the peak， the number of seeds collected decreased significantly. There was a phenomenon of “secondary seed drop”， which prolonged the drop time of seeds. （4） The number of seeds collected decreased with the increases of the distance from the collection frame to the mother tree， 98% of seeds fell within 10 m from the mother tree. Only four seeds were collected in the 30 m frames. （5） The number of seeds collected from the west was the largest， which might be related to the lower terrain in the west direction.
In order to investigate the effects of saline-alkali stress on the plant growth， seedling of Heucheramicrantha ‘Silver Fan’ was used as materials， and 30， 60， 90， 120 and 150 mmol·L-1 NaCl and NaHCO3， and 20， 30， 40， 50 and 60 mmol·L-1 Na2CO3， were used to simulate salt stress， salt alkali stress， and alkali stress， respectively. The experiment used 1/4 Hoagland nutrient solution as the control， and used water culture method to treat seedlings for 0， 7 and 14 d. The response of plants was observed from aspects such as salt damage rate and physiological indicators， and the effects of salt stress on the growth of ‘Silver Fan’ seedlings were analyzed and evaluated by principal component analysis of 7 indicators. The results showed that under different salt alkali stress treatments， the relative conductivity and malondialdehyde content（MDA） of the seedlings showed an increasing trend with time and concentration. The seedlings treated with 30 mmol·L-1 NaCl or NaHCO3 showed no obvious symptoms of salt damage， and all physiological indicators showed an upward trend with the prolongation of treatment time； With the increase of concentration and stress time， the salt damage index of seedlings increased， but the ornamental value decreased. The overall trend of superoxide dismutase（SOD） increased first and then decreased， reaching the maximum value at 90 mmol·L-1 NaCl and 60 mmol·L-1 NaHCO3， respectively. Under the same stress time， the contents of chlorophyll（Chl）， chlorophyll a（Chla）， and chlorophyll b（Chlb） decreased continuously， while ρ（Chla）/ρ（Chlb） increased with the increase of stress concentration. Under different concentrations of Na2CO3 stress， the SOD activity generally showed an upward trend， reaching the maximum value at 50 mmol·L-1， and the contents of Chl， Chla， and Chlb generally showed a downward trend. However， under the same time conditions of stress， ρ（Chla）/ρ（Chlb） decreased first and then increased with the concentration increasing， and the ratio of ρ（Chla）/ρ（Chlb） was the smallest under 40 mmol·L-1 treatment. In general， ‘Silver Fan’ seedlings had a certain salt alkali resistance ability， and could grow at NaCl concentration<90 mmol·L-1， NaHCO3 concentration<60 mmol·L-1， and Na2CO3 concentration< 40 mmol·L-1， and had certain ornamental value， respectively. The results of principal component analysis showed that the relative conductivity， Chla， and Chlb contents could be used as indicators for evaluating the salt alkali resistance of the ‘Silver Fan’.
To explore the effect of tree age of ancient Platycladus orientalis on rooting of cuttings propagated from them and the physiological mechanism during the cutting process， the cuttings of 5， 100， 300 and 700 years P. orientalis female trees were used as scions respectively， and the phloem at the base of the cutting at rooting stages［0 d （S1， stage of before cutting）， 35 d（S2， stage of callus formation）， 65 d（S3， stage of adventitious root formation）， 95 d（S4， stage of adventitious root elongation）］ were harvested as the materials and the dynamic changes in the physiological indicators were measured， and the rooting rates and the numbers of rooted cuttings were counted respectively. The results showed that both of the rooting rates and the numbers of rooted cuttings propagated from ancient P. orientalis were significantly less than those of five years ones（P<0.05）. The nutrients（total sugar and total protein）， activities of antioxidative enzymes（polyphenol oxidase（PPO），peroxidase（POD）， superoxide dismutase（SOD）） and hormones（Indole-3-acetic acid（IAA）， zeatin riboside（ZR）） contents of the cuttings of five years donors were significantly more than those of ancient P. orientalis donors at all rooting stages， indicating that the high levels of these substances facilitated the rooting of the cuttings（P<0.05）. The contents of malondialdehyde（MDA）， abscisic acid（ABA）， and gibberellin（GA） showed a significant increase with increasing tree ages， indicating that the cuttings of ancient P. orientalis contained more harmful substances and hormones that inhibited rooting（P<0.05）. The nutrients（total sugar and total protein） and hormone（IAA and GA） contents showed a trend increased first and then decreased throughout the four stages， and it was worth noting that the contents reached maximum value at S3. On the contrary， ABA contents at S3 were significantly lower than that of another three stages（P<0.05）. The results indicated that the stage of adventitious root formation（S3） was a critical stage during the cutting process（P<0.05）. The larger the ratio of ω（IAA）/ω（ABA） and ω（ZR）/ω（ABA） were， the better for adventitious root formation. Tree ages significantly affected the rooting rate of P. orientalis cuttings， but there was no significant difference in the rooting rate of cuttings of ancient P. orientalis of different ages. Therefore， the reasons for difficulties in rooting of cuttings from ancient P. orientalis were mainly attributable to the lack of nutrients（total sugar and total protein）， activities of antioxidative enzymes（PPO， POD， and SOD） and endogenous hormones（IAA and ZR） beneficial to rooting.
In order to explore the law of flower color change of Hibiscussyriacus during the flowering process and the influence of physical and chemical factors such as pH， metal ions and water content on its flower color， the composition and physicochemical factors of anthocyanins in the petals of H. syriacus ‘Qiansiban’ and ‘White Chiffon’ at different blossoming periods were studied respectively by the color chromato-meter， ion emission spectrometer and high performance liquid chromatography-mass spectrometry. The results showed that： （1）In terms of the composition of anthocyanins， 10 kinds of flavonoids such as Quercetin-3-glucoside， Luteolin-7-O-glucoside， and Santolol-7-O-glucoside were detected and identified in the petals of the two varieties， and 5 kinds of anthocyanins such as Mallorin-3-O-glucoside were detected and identified in the H. syriacus ‘Qiansiban’， and no anthocyanins were detected in the H. syriacus ‘White Chiffon’. （2）In the process of blossoming， the brightness of the flower color increased， the color degree decreased， and the color changed from purplish red to lavender， and light yellow to white respectively. During the blossoming， the composition of anthocyanins remained unchanged， and the content of anthocyanins and total anthocyanins gradually decreased in H. syriacus ‘Qiansiban’. （3）The pH of petals in H. syriacus ‘Qiansiban’ and ‘White Chiffon’ were both acidic， and the activities of Peroxidase（POD） and Polyphenol oxidase（PPO） showed significant difference in different periods. Among them， POD activity in H. syriacus ‘Qiansiban’ was higher than that in H. syriacus ‘White Chiffon’， while PPO activity was the opposite； calcium and magnesium ions were the highest content of metal ions in H. syriacus petals， while copper， iron， manganese， zinc and other metal ions had low content in H. syriacus petals. （4）In terms of correlation analysis， during the blossoming of H. syriacus ‘Qiansiban’， the color degree C* was significantly positively correlated with hue a*， and significantly positively correlated with calcium ion， iron ion and manganese ion respectively； during the blossoming of H. syriacus ‘White Chiffon’， the color degree C* was significantly positively correlated with hue b* and PPO activity， and negatively correlated with hue a* respectively. The research showed that the anthocyanins were the material basis of flower color change of H. syriacus flower petals. Besides anthocyanin content， the flower color change process was also closely related to the content of calcium， iron， manganese and other metal ions. PPO activity was a potential biochemical factor to promote the degradation of flavonoids in white flower varieties.
In order to investigate the effects of drought on the interspecific relationship and growth of the invasive plant Bidens pilosa and the native species Buddleja lindleyana， two methods were designed： interspecific group（one plant of each of two species were planted in a pot） and baffled group（a baffle separated the two plants in the interspecific group）， and two water treatments were applied， including the drought group （30%-35% saturated moisture content） and control group（90%-100% saturated moisture content）， and plant morphological characteristics， biomass， relative growth rate， and relative neighbor effect index of each plant feature were measured respectively. The results showed that： （1）under both drought conditions， interspecific interactions promoted the root， stem， leaf， and total biomass of Bidens pilosa， whereas water availability altered the interspecific interactions of Buddleja lindleyana， with competition under the drought treatment and facilitation under the control treatment； （2）under drought conditions， interspecific interactions increased the relative growth rate and root-to-shoot ratio of Bidens pilosa root， stem， and leaf biomass， and decreased the specific leaf area and root-to-shoot ratio of Buddleja lindleyana（P<0.05）. （3）Interspecific interactions significantly promoted the growth of root length， root surface area， and root tip number in both species（P<0.05）. The results indicate that interspecific interactions promote the growth performance of Bidens pilosa under drought conditions， provid it with a competitive advantage in arid habitats， potentially as part of its invasion strategy.
The pollen of 22 species of Saussurea and 1 species of Himalaiella were observed and compared by scanning electron microscopy to understand the degree of differentiation at the level of pollen morphology， and the pollen cluster analysis was carried out to provide a sporological basis for the classification of this genus， and further provided germplasm resources utilization of Saussurea in the region. The results showed that： （1）There were 20 species of 23 plants with subspherical pollen shape and three were oblate spherical； most of the pollen volume belonged to medium-sized pollen， and the overall type was relatively evolved. （2）Except for Saussurea Nephrolepis， which was a four-pore pollen， the pollen of the other 22 species had three pore grooves. （3）The outer wall ornamentation of pollen of 23 species could be divided into seven types： seven types of reticulate， six types of reticular and granular， six types of cavernous， and there were one smooth， one spine-based cavernous and one interspinous with wrinkled waves， one granular and one ruffled. （4）Cluster analysis based on pollen micromorphology of 23 plant species showed some consistency with the plant classification system and was even relatively clear among some subgenera. The results of this paper suggested that pollen micromorphological features might provide a basis for species identification in this genus.
To explore the effects of exogenous salicylic acid（SA）added on plants， the physiological indices including membrane lipid peroxidation， reactive oxygen species accumulation， antioxidant enzyme activities， and antioxidant contents as well as gene expression in the leaves of Davidia involucrata seedlings under salt stress were investigated respectively. The results revealed that， under salt stress， the application of SA significantly reduced the relative electrolyte leakage， and inhibited the accumulation of malondialdehyde（MDA）and ROS， and increased the relative water content， activities of antioxidant enzymes（i.e.， SOD， POD， and APX）， and glutathione（GSH）contents. Moreover， treatment with SA resulted in differential expression of 2 581 genes（1 516 up-regulated and 1 065 down-regulated） under salt stress. KEGG analysis indicated that differentially expressed genes（DEGs）were enriched in nine pathways including phenylpropanoid biosynthesis. In addition， transcriptome sequencing and quantitative real-time PCR（qRT-PCR）results showed that exogenous SA significantly induced the expression of transcription factor genes including DiWRKY40， DiNAC25， DiMYB4， and DiMYB86 under salt stress. These results suggested that exogenous SA might stimulate stress responses in salt-treated D. involucrata seedlings and trigger variation in gene expression， resulting in alleviation of salt injury in D. involucrata seedlings.
To explore the function roles of K+-efflux-antiporters KEA1 and KEA2 in Arabidopsis thaliana， wild type and kea1kea2 knock-down mutants of Arabidopsis thaliana were used as materials to investigate the effects of KEA1 and KEA2 on plant growth and development. Phenotypic analysis， propidium iodide staining to observe the structure of roots， high performance liquid chromatography to determine endogenous sugar content， transcriptome sequencing and qRT-PCR to analyze the relative expression levels of related genes， histochemical staining to detect the distribution of superoxide anion in leaves were performed respectively. The results showed that the root length of the kea1kea2 mutant was significantly shorter than that of the wild-type Col-0 plant in the absence of sucrose. Further observation showed that compared with the wild-type， the root meristem zone of kea1kea2 mutant was shorter， the endogenous sucrose content was decreased， and more O2·- was distributed in the leaves of the kea1kea2 mutant. However，when 30 g·L-1 sucrose was exogenously added， there was no significant difference in root length between the wild-type and kea1kea2 mutant. Transcriptome analysis revealed that the expression of many key genes involved in sucrose signals and root growth were repressed in the kea1kea2 mutant. In summary， the results suggested that sucrose might affect AtKEA1and AtKEA2 to regulate root growth in Arabidopsis seedlings.
To provide reference for early selection of fast-growing and adaptable varieties， the difference in growth， photosynthetic physiology， and root tip ion flux were analyzed among in five poplar varieties. The annual seedlings of Populus × euramericana ‘Bofeng 3’， P. × euramericana ‘Bofeng 1’， P. × euramericana ‘Xixiong 1’， P. × euramericana ‘Zhongxiong 7 ’， and P. deltoides × P. suaveolens cl. ‘Zhongxiong 4’ were selected as materials. Growth indexes including plant height and ground diameter were measured at 0 and 30 days under normal culture conditions， respectively. Leaf number， single leaf area， leaf length， leaf width， photosynthetic parameters including Pn， Ci， Gs， Tr， SPAD and K+， Ca2+， H+ ion flux of roots were measured at 10， 20 and 30 days， respectively. Under 30 days normal management， There were significant differences in plant height growth among the five varieties， from high to low， it was ‘Zhongxiong 4’， ‘Xixiong 1’， ‘Bofeng 3’， ‘Zhongxiong 7’ and ‘Bofeng 1’. Among them， the photosynthetic characteristics and transpiration rate of ‘Bofeng 1’ were the largest， and those of ‘Zhongxiong 4’ were the smallest. However， the single leaf area（（57.49±2.37） cm2）， total leaf area（（1 721.10±28.59） cm2）， net photosynthetic rate （（17 863.10± 910.21） μmol·m-2·s-1） and water utilization rate（（3.15±0.06）μmol·mmol-1） of ‘Zhongxiong 4’ were significantly decreased. were the largest. The efflux velocity of K+ was the slowest（（62.68±0.45） pmol·cm-2·g-1）， and the influx velocity of Ca2+ was the fastest（（-74.24±1.29） pmol·cm-2·g-1）. The net photosynthetic rate （（8 539.70±164.64） μmol·m-2·s-1） and water utilization rate（（2.64±0.07） μmol·mmol-1） of ‘Bofeng 1’ were the lowest， and the outflow velocity of K+ was（130.81±1.71） pmol·cm-2·g-1. The Ca2+ influx velocity（（-34.43±0.84） pmol·cm-2·g-1） was the slowest. In summary， among the five varieties， ‘Zhongxiong 4’ might have potential strong environmental adaptability， with the highest total leaf area， Pn and WUE， the lowest Tr， the smallest K+ efflux， largest Ca2+ influx of and most active H+ of root tip， and best plant height growth performance， which might be suitable for planting a wider range.
In order to explore the response strategies of plateau wetland plants to increasing temperature and CO2 concentration， Typha orientalis， a common emergent plant in plateau areas， was selected as the research object to detect its leaf functional traits， and the simulated climatic change of increasing 2 ℃ temperature and CO2 concentration doubling were designed by constructing a capping artificial growth chamber. The results showed that： （1）The net photosynthetic rate， stomatal conductance， intercellular CO2 molar fraction and transpiration rate of T. orientalis under the CO2 concentration doubling treatment were significantly reduced （P<0.05）； while the net photosynthetic rate and stomatal conductance of T. orientalis were also significantly reduced under the warming treatment（P<0.05） compared with the control group. The results indicated that the photosynthetic carbon assimilation capacity of T. orientalis was significantly reduced under the temperature increasing and CO2 concentration doubling conditions（P<0.05）. （2）The vein density of T. orientalis leaves increased significantly under the CO2 concentration doubling treatment； while the vein density and stomatal density increased significantly， but the vascular bundle area and catheter area decreased significantly（P<0.05） under the warming treatment compared with the control group. The results reflected the enhancement of water transport and transpiration loss capacity but the reducing of water use efficiency of T. orientalis under the conditions of warming and CO2 concentration increasing. （3）The correlations among leaf photosynthetic parameters were looser， while the correlations between net photosynthetic rate and leaf structure traits were stronger under warming and CO2 concentration doubling treatments than control group. The results showed that the functional synergistic or trade-off effects of leaf functional traits of T. orientalis were enhanced significantly by increasing temperature and CO2 concentration.
Bryophyte is an important component of the surface ecosystem. The physiological response of bryophyte（Syntrichia caninervis， Bryum argenteum and Plagiomnium acutum） to nitrogen deposition could provide insights into how to use bryophyte scientifically and rationally to indicate the atmospheric nitrogen deposition. Three bryophytes in the northwest of China were selected as materials， and four different nitrogen treatment concentrations（0（N0）， 2（N2）， 4（N4）， 6（N6） g·m-2） were set up， the physiological responses of three bryophytes to the above nitrogen concentration gradients were indicated by measuring the contents of chlorophyll， osmotic regulators and antioxidant enzyme activities. The results showed that：（1）P. acutum of chlorophyll a and chlorophyll b was promoted by 4 nitrogen treatments， especially by N4 treatment. However， N2 had significant inhibitory effects on chlorophyll a and chlorophyll b of B. argenteum and S. caninervis. （2）Proline（Pro）， soluble sugar（SS） and soluble protein（SP） were produced in bryophytes to regulate cell osmotic balance. The contents of Pro， SS and SP in B. argenteum and P. acutum all increased under different nitrogen concentrations， but the contents of Pro， SS and SP in mosses decreased under low nitrogen treatment， indicating S. caninervis were more sensitive to N. （3）under the given nitrogen addition treatment， the antioxidant enzyme activities of three bryophytes were promoted by low concentration of nitrogen， but inhibited by high concentration of nitrogen. （4）SOD and CAT played major role in the regulation of the antioxidant system in S. caninervis， B. argenteum and P. acutum， respectively. In conclusion， S. caninervis was the most sensitive to nitrogen increase of the three bryophytes， followed by P. acutum. And B. argenteum， suggesting that S. caninervis could be used as an indicator plant for atmospheric nitrogen deposition.
To investigate the physiological adaptability of mangrove plants under different salinity， the influences of different salinity（0， 5%， 10%， 15%， 20%， 25%， 30%， 35%） on the growth of six mangrove species（Bruguiera gymnorhiza， Ceriops tagal， Rhizophora stylosa， Bruguiera sexangula， Aegiceras corniculatum， Kandelia obovata） were assayed， and the morphological and physiological characteristics of six species were determined respectively， including the biomass， plant height increment， base diameter increment， net photosynthetic rate， chlorophyll a content， chlorophyll b content， total chlorophyll content， superoxide dismutase（SOD） activity， proline（Pro） content and malondialdehyde（MDA） content. The results showed that the 5%-20% was suitable salinity for the growth of six mangrove seedlings， and the Parmentiera cerifera had high salt tolerance. The SOD activity， Pro content and MDA content and chlorophyll content of six mangrove seedlings increased， but net photosynthetic rate and growth rate decreased under salt stress. The results showed that the photosynthesis of the six species seedlings decreased under salt stress， the photosynthetic rate increased by increasing the chlorophyll content， and the plant stress resistance might be improved by increasing the SOD activity， Pro content and MDA content in the leaves.
In order to explore the the “fertilizer island” effect in different spatial positions of two shrubs in the Gurbantunggut Desert， the dominant shrubs in the desert-Eremosparton songoricum and Calligonum mongolicum were used as research objects. Sampling points were set up by extending outward at 20（A）， 60（B）， 100（C）， and 140 cm（D） with the shrub root as the center， each sampling point was sampled at three soil depths （0<h≤5 cm， 5 cm<h≤10 cm， 10 cm<h≤20 cm， and the soil nutrient content and enrichment at different spatial locations were analyzed respectively. The results indicated that： （1）Both E. songoricum and C. mongolicum had a “fertilizer island” effect， and there were significant differences in soil nutrient content among different species and spatial locations（P<0.05）. The variation trend of the two plant soil nutrients in different spatial distributions was the same， that was， in the horizontal direction， they gradually decreased as the distance from the center of the shrub increased. Among them， the soil SOM， AK， and TN contents of E. songoricum at location D were decreased by an average of 58.16%， 52.94%， and 68.18% compared to A， respectively. The content of SOM， AK， TN， and EC in the soil at location D were decreased by an average of 61.38%， 13.33%， 69.23%， and 21.81%， respectively， compared to location A. In the vertical direction， the content of SOM， AK， and TN in the soil of the two types of plants showed the highest nutrient content in the surface soil， and showed a decreasing trend with the increase of soil depth. The content of AK， pH， and N- N O 3 - in the rhizosphere soil of C. mongolicum was significantly higher than that of E. songoricum（P<0.05）. （2）The enrichment rates of SOM， AK， TN， and total phosphorus（TP） in the soil of the two shrubs showed consistent trends， that was， the enrichment rate of soil nutrients gradually decreased with the increase of soil depth， and the enrichment rate of soil nutrients gradually decreased with the increase of shrub center. （3）There was a significant correlation（P<0.05） between soil enrichment rates at different spatial locations and plant height and crown width. The plant height and crown width of E. songoricum and C. mongolicum showed a significant positive correlation with soil SOM， TN， N- N O 3 - enrichment rates. In general， both plants showed a “fertilizer island effect”， with obvious spatial heterogeneity in different spatial distributions， different plants had different enrichment capacities for soil nutrients， and their “fertilizer island” effects were also different， with obvious species effects.
In order to explore the response of photosynthetic physiological characteristics to different pruning intensities in Populus of middle and high forest age， 10-year-old triploid Populustomentosa asexual lines B301 and S86 were used as materials， light pruning（pruning the lower 1/3 of the canopy） and heavy pruning（pruning the lower 1/2 of the canopy） and unpruned trees as the control were adopted respectively. The results showed that pruning had no significant effect on the growth rate of height， diameter at breast height and wood volume of 10-year-old Populus， but heavy pruning increased the net photosynthetic rate（Pn）， transpiration rate（Tr）， and stomatal conductance（Gs） of their remaining leaves and enhanced material synthesis at the single-leaf level， while pruning had no significant effect on instantaneous water use efficiency（WUE）. From a comprehensive analysis of growth and physiology， pruning the lower 1/2 of the canopy could improve the physiological condition of 10-year-old Populus tomentosa， but had no significant effect on the growth of the stand.
In order to reveal the adaptation strategy of Populus tomentosa to the environment， and to provide scientific basis for better forest management， the 10-， 20- and 35-year-old Populus tomentosa in the Yellow River floodplain of western Shandong Province were taken as the research objects， and 10 indicators of branch and leaf functional traits were measured， and the changes of community functional traits with the different stand ages were analyzed， and the main indicators affecting the changes of functional traits were clarified， and the relationships between functional traits and environmental factors were analyzed respectively. The results showed that （1）the coefficient of variation of branch density was the smallest， 10.431， and the coefficient of variation of leaf nitrogen-phosphorus ratio was 94.243， which indicated that leaf nitrogen-phosphorus ratio was greatly affected by the different stand ages， while branch density was more stable. leaf nitrogen-phosphorus ratios were significantly lower than 14 in three stand ages， indicated that the growth was manly limited by nitrogen. （2）As the age of the forest increased， the soil environment was improved， soil total nitrogen and soil available potassium showed an increasing trend， and the soil bulk density showed a decreasing trend， these changes were conducive to the better growth of P.tomentosa. （3）Among the environmental factors， stand density， soil available potassium content， soil bulk density and soil water content were the environmental factors that significantly affecting the growth of P.tomentosa. The results proved that the functional traits of the P.tomentosa showed strong adaptability in balancing growth and environmental changes at different stand ages， and that the growth of P.tomentosa in this region was mainly limited by nitrogen， so nitrogen fertilizer could be applied appropriately to facilitate its growth.
In order to clarify the differences in the adaptability of branches and leaves of different oriental cherry cultivars in resource utilization， biomass allocation， and leaf display strategies， and the effect of current twig stem structure on leaf spreading efficiency were discussed. 15 oriental cherry cultivars in Fuzhou National Forest Park were used as materials， and the stem length and stem slender ratio were used as the proxy of stem structure traits， and the leaf density， leaf/stem mass ratio and leaf area ratio were used to characterize the leaf spreading efficiency， and oriental cherry cultivars with greater leaf display efficiency were screened， the standardized major axis estimation （SMA） was employed to identify whether there was a significant difference on the link between stem structure and leaf display efficiency among different cultivars. The results showed that： （1）In 15 oriental cherry cultivars， there was a substantial negative relationship between stem structure and leaf display efficiency， with stem length and stem slender ratio increased， leaf density， leaf/stem mass ratio and leaf area ratio all steadily decreased respectively. （2）The leaf/stem mass ratio， leaf area ratio and leaf density of 15 cherry cultivars differed with stem structure increased. ‘Hejin’（HJ）， ‘Taiwan mudan’（TWMD） and ‘Yunnan’（YNDY） performed better in terms of leaf density. In terms of leaf area ratio， ‘Danhong’（DH）， YNDY and HJ performed better； that was， YNDY and HJ had higher leaf density and leaf area ratio under a specific stem structure. （3）Under specific stem structures， ‘Xishi’（XS）， ‘Chumeiren’（CMR）， ‘Jingweng’（JW） and HJ showed greater leaf/stem mass ratios. Combined with florescence， ‘Hejin’（HJ） had relatively higher leaf spreading efficiency and longer flowering period， which could be widely planted.
In order to explore the population structure and dynamic characteristics of Chunia bucklandioides in Diaoluo Mountain of Hainan， the local wild population of C. bucklandioides was taken as materials， and the concentrated distribution area of the population was set as a typical sample plot to survey， and construction of population age structure instead of space for time was designed. The current population structure and dynamic characteristics were analyzed by the dynamic quantitative analysis， survival curve drawing and survival function calculating， and the future development trend of C. bucklandioides was speculated by time sequence prediction model. The results showed that： （1）The age structure of C. bucklandioides population in Diaoluo Mountain was close to an irregular pyramid type. Dynamic quantitative analysis showed that the population was a growing population， but there was a decline trend from the age class Ⅰ to Ⅲ. The population had weak growth， poor stability， high sensitivity to external interference， and a trend towards a stable population. （2）With the increase of age class， the number of standardized survival individuals decreased， the life expectancy decreased， and the mortality and vanish rate showed an upward trend. The survival curve tended to be Deevey-Ⅱ type. （3）Survival analysis showed that the population of C. bucklandioides in Diaoluo Mountain increased in the early stage， stabilized in the middle stage， and declined in the late stage. （4） After two， four and six age classes in the future， there would be a gradually decreasing trend from I to Ⅲ age class， and slightly increasing trend from Ⅳ to Ⅶ age class. The self-renewal ability of young seedlings was insufficient， and there was a risk of population shrinkage and decline. Consequently， habitat fragmentation， small distribution range， low seed yield and insufficient young individuals might be the main factors leading to the endangerment of C. bucklandioides in Diaoluo Mountain. The results suggested to promote the rejuvenation and renewal of C. bucklandioides population by setting up small nature reserve， assisting seed germination， accelerating artificial cultivation technology research， artificially expanding population size and quantity， and strengthening basic research.
