To explore whether the fungi from Parametarhizium， namely P. hingganense or P. changbaiense， a newly discovered fungus from forest litters in northeast China， could improve plant growth under salt and alkali stress， the mung bean seeds were treated with the fungi， followed by the examinations on the phenotypic changes， and alterations on the photosynthesis， chlorophyll fluorescence parameters， osmolyte contents， ROS levels， and antioxidant enzyme activities were detected respectively. The results showed that the biomass of mung bean plants treated with P. hingganense or P. changbaiense were higher under no-stress， salt and alkali stress conditions than untreated plants. Under salt and alkali stress， two fungus-treated plants maintained a high photosynthetic activity， elevated proline content， decreased malondialdehyde（MDA） content， and increased the activities of antioxidant enzymes POD， SOD and CAT in different degrees. In conclusion， through maintenance of photosynthesis， raising osmotic potential， and antioxidant capacity， treatment of the fungi from Parametarhizium alleviated the salt and alkali stress on mung bean. P. hingganense might significantly alleviate salt stress damage， while P. changbaiense might significantly improve the growth of mung bean under alkali stress.
To explore the effects of different thinning intensity on the growth and wood properties of Populus pseudo-cathyana×Populus deltoids plantation， and to provide a theoretical basis for cultivating high-quality industrial resources of poplar in northeast China， the 18-year old Populus pseudo-cathyana×Populus deltoids was used as the material， and the initial plant row spacing of 2 m×3 m was used as the control， and the thinning treatments of 3 m×3 m， 6 m×3 m， 4 m×6 m were set up. The growth characteristics（tree height， DBH， 2 m diameter， crown width） and wood properties（basic density， fiber length， fiber width， hemicellulose content， cellulose content， semi-cellulose content， lignin content） of the experimental forest were measured in the 5th year after thinning， and the volume per tree and the storage per unit area were calculated using tree height and DBH. The results of variance analysis showed that all indexes were significantly different except basic density （P<0.01）. The results of mean analysis showed that the mean values of each growth index and lignin content reached the maximum when the row spacing was 6 m×3 m， and the other wood indexes reached the maximum when the row spacing was 4 m×3 m or 6 m×4 m. The variation of phenotypic coefficient of each index ranged from 3.35% to 29.87%. In addition to the basic density， the repetitive force of each index exceeded 0.590. The results of correlation analysis showed that there were significant positive correlations among the growth indicators（0.690<r<0.993）， but the correlation between wood traits and growth traits was weak. It was found that Qi reached the maximum when the row spacing was 6 m×3 m， 4 m×6 m and 4 m×6 m， respectively， by using growth traits， wood traits and combined growth and wood traits as evaluation indexes. Thinning might promote the growth of stand and improve the wood property of the forest， and the wood property and the comprehensive improvement effect of the forest growth and wood would be better when the row spacing of the trees is 4 m×6 m. The best growth results were obtained when the row spacing was 6 m×3 m. Therefore， suitable thinning intensity might be selected according to different cultivation objectives for the cultivation of poplar high quality industrial resources in northeast China in the future.
To investigate the vertical distribution of root biomass（diameter≤2 mm） and root length density of Pinus tabulaeformis and Cupressus chengiana plantations in the arid valleys of the upper Minjiang River， and to analyze the carbon allocation strategy of fine root system in different soil layers， and to provide reference for vegetation restoration in the arid valleys of the upper Minjiang River. P. tabulaeformis and C. chengiana plantations were sampled by soil corer method， and the root biomass and root length density of absorptive roots（first to third order） and transport roots（≥fourth order） in different depth（h）（0 cm<h≤15 cm and 15 cm<h≤30 cm） were measured， as well as the proportions biomass and length density of absorptive roots to the total fine roots. The results showed that： the absorptive root biomass and root length density of P. tabulaeformis and C. chengiana were significantly higher in 0 cm<h≤15 cm than those in 15 cm<h≤30 cm， and the transport root biomass and root length density were not significantly different between soil layers； the proportions biomass and length density of absorptive roots to the total fine roots in 0 cm<h≤15 cm were significantly higher than that in 15 cm<h≤30 cm（P<0.05）； the proportions biomass and length density of absorptive roots to the total fine roots in 0 cm<h≤15 cm and 15 cm<h≤30 cm of C. chengiana were significantly higher than those of P. tabulaeformis（P<0.05）. These findings suggested that more carbon was allocated to the absorptive roots in the surface soil layers with the highest nutrient availability in P. tabulaeformis and C. chengiana root system.
Since the regeneration of Tilia amurensis is difficult under full light conditions， and vegetation control can promote the growth of target species by changing light conditions and soil quality. In order to provide the support for the cultivation of T. amurensis， the effects of vegetation control intensity on root traits and soil factors of seedlings were investigated. T. amurensis monocultures（Five-year-old） with inter-row and intra-row spaces of 1.5 m×1.5 m were used as materials， and vegetation control treatments with different intensities T30， T50 and T75（clearing vegetation in the radius of 30， 50， 75 cm around T. amurensis seedlings） and control treatment（CK） were set. The morphological traits， total nutrient content， and non-structural carbon content in the absorptive roots and transport roots of T. amurensis seedlings， as well as soil variables were measured under different treatments， and the effects of vegetation control on root traits and soil conditions were revealed. Vegetation control significantly changed the light intensity in the environment of T. amurensis seedlings， among which the light intensity under T75 treatment was the maximum， and the light intensity decreased with the weakening of vegetation control intensity（P<0.05）. Vegetation control significantly reduced the contents of total carbon， total nitrogen， available nitrogen， and available phosphorus in the soil. With the decrease of vegetation control intensity， the fine root diameter， carbon to phosphorus ratio， soluble sugar and starch contents decreased， while the specific surface area， specific root length， total carbon， total nitrogen and total phosphorus contents increased. Soil variables factors to the variation of root traits for absorptive roots and transport roots were 43.2% and 37.9%， respectively. The greater the vegetation control intensity， the greater the light intensity obtained by T. amurensis saplings， and the root morphology， stoichiometry and physiological traits of T. amurensis saplings took adaptive changes with the change of vegetation control intensity. The root specific surface area， specific root length， total carbon， total nitrogen and total phosphorus contents were increased to enhance the adaptability to low light conditions. The changes of light conditions and soil factors under vegetation control might be the two main factors to explain the root trait changes of T. amurensis saplings.
In order to explore the difference and influencing factors of the number of regenerated seedlings of Pinus schrenkiana on different decomposed grades of fallen wood， the relationship between the number and height levels of regenerated seedlings on different decomposed grades of fallen wood， and the water content， surface area， slope， slope direction and elevation of fallen wood were investigated respectively. The results showed that the probability of seedlings appearing on fallen wood with different decay grades was different， but the seedlings survival rate increased with the increase the decay grade of fallen wood. The height level structure of fallen wood seedlings with different decomposition grades showed obvious growth characteristics， with seedlings at height of 0-5 cm being the most. The water content of fallen wood had a significant impact on the number of seedlings on grade Ⅰ and grade Ⅱ decayed fallen wood（P<0.05）， while the surface area of fallen wood had a significant impact on the number of seedlings on grade Ⅱ， Ⅲ and Ⅳ decayed fallen wood（P<0.01）， but the slope and altitude had no significant impact on the number of regenerated seedlings on each grade of decayed fallen wood（P<0.05）. Further analysis of the influencing factors on the number of seedlings at different height levels showed that water content had a very significant impact on the number of A1（0-5 cm） and A2（5.1-10.0 cm） height level regenerated seedlings on fallen wood with grade Ⅱ decay（P<0.01）， and the surface area of fallen wood had a significant impact on the number of A1 height level seedlings on fallen wood with grade Ⅱ and Ⅲ decay（P<0.05）； On the fallen wood with grade Ⅳ decay， these factors had no significant impact on the number of regenerated seedlings at different height grades（P<0.05）. The surface area and slope direction of fallen trees had a significant impact on the number of dead seedlings on fallen trees. The water content on low-level decomposed fallen wood was the main factor affecting the number of regenerated seedlings， while for high-grade fallen wood， the surface area was the main factor. In contrast， seedlings with lower heights were more susceptible to the impact.
Understanding the growth dynamics of tree xylem in arid and semi-arid areas of China and its response to climatic factors is crucial for assessing and predicting forest productivity and carbon sequestration potential under climate change. In this study， the intra-annual xylem formation of four Quercus mongolica in Liupan Mountain Nature Reserve of Ningxia were monitored by micro-core sampling technique in two growing seasons（2019 and 2020）， and mixed linear model was used to explore the effects of temperature and precipitation on xylem growth rates. The results showed that there was no significant difference in intra-annual xylem formation dynamics between the two years（P>0.05）. The onset of xylem formation started from early April and ceased from mid-to-late September， resulting in a growing season length of （177±17） days（2019） and （165±24） days（2020）. The results of the mixed linear model showed that the annual xylem growth rate of Q. mongolica was positively correlated with the maximum， mean， minimum temperatures， as well as total precipitation in the preceding 7， 10 and 15 days（P<0.01）. Under global change， the xylem growth of Q. mongolica may benefit from future warm and humid climate conditions in Liupan Mountain Nature Reserve， Ningxia.
To explore the effects of pectinase on distribution of arabinogalactan proteins（AGPs） in fruits at different developmental stages，and to provide anatomical evidence for revealing the effects of pectinase on fruit ripening and softening， the fruits of Ziziphus jujuba ‘Lingwu Changzao’ at four different development stages were treated with three different concentrations pectinase， and AGPs epitopes analysis in situ at cellular level of fruits was performed using immunocytochemistry technique. The results showed that the fluorescence intensity of the antigens recognized by JIM13 and JIM8 and MAC204 antibodies was varied in different tissues during the development of fruit at each stage. When fruit tissues were treated with 0.028 U·mL-1（E1） pectinase， there were no obvious changes in pericarp tissue structure， AGPs antigen epitopes in cell wall surface and intercellular space of pericarp and interior parenchyma cells decreased. When fruit tissues were treated with 0.056 U·mL-1（E2） and 0.084 U·mL-1（E3）pectinase， disintegration degree of cell wall in fruit tissue increased， the amount of AGPs epitopes detected in cell wall of pericarp and inner parenchyma cells decreased gradually， an increase in pectinase concentration resulted in a greater effect of AGPs on the arrangement of all epitopes in fruit and a lower fluorescence signal. After treatment with pectinase concentration up to 0.084 U·mL-1（E3）， Calcofluor White staining revealed fluorescence attenuation or reduction to varying degrees in the cell wall region， disturbance of AGPs distribution and absence of antigen epitopes were associated with changes of cellulose assembly in cells. The results indicated that the distribution of AGPs carbohydrates differed in fruits at different stages， which was related to changes in tissue structure. The absence of AGPs glycan chains in the presence of pectinase led to the block of the establishment of correlations between cell wall components and cell wall structure remodeling， and the changes in the whole cell wall structures were induced and fruit ripening was affected.
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.
In order to explore the effects of nitrogen addition on the growth and non-structural carbohydrate（NSC） content of Cinnamomum bodinieri seedlings in rare earth mine tailings， one-year-old C.bodinieri cuttings were used as materials， and calcium ammonium nitrate was used as nitrogen fertilizer（containing N 15%）， and three nitrogen levels（CK（0）， N1（1.8 g per plant）， N2（3.6 g per plant）） were set up to analyze the differences in root growth， biomass distribution and NSC of C.bodinieri seedlings under three nitrogen addition levels， and to explore the response of C.bodinieri in rare earth tailings to nitrogen addition. The results showed that： Nitrogen addition increased the biomass accumulation of different tissues of C.bodinieri seedlings in rare earth tailings， and the leaf biomass and canopy biomass at N1 level were significantly increased by 44.75% and 57.43%（P<0.05）， respectively， compared with N2. Compared with CK and N1 treatment， the leaf mass ratio of N2 level was significantly increased by 123.53% and 15.85%（P<0.05）， respectively. Nitrogen addition significantly promoted the root length and root surface area of both coarse roots（diameter>2mm） and fine roots（diameter≤2mm）（P<0.05）， and the promotion effect of N1 treatment was the most significant（P<0.05）. The specific root length and specific surface area under N2 treatment were higher than those of CK and N1， and significantly different from CK（P<0.05）. For NSC， N1 treatment increased the soluble sugar mass fraction in leaves and stems， while the NSC mass fraction of fine roots under N2 treatment was significantly lower than that of CK and N1 by 46.49% and 28.61%， respectively. In summary， during vegetation restoration in rare earth mine tailings， 1.8 g per plant calcium ammonium nitrate fertilizer might be suitable for fertilization management of C.bodinieri 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.
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.
In order to investigate whether brassinosteroids（BRs）-induced chilling tolerance is regulated through nitric oxide（NO） signaling molecule， the suspension cultured cells of Chorispora bungeana were treated with 24-epibrassinolide（EBR）， NO donor SNP， NO scavenger PTIO， nitric oxide synthase（NOS） inhibitor L-NAME， EBR+PTIO and EBR+L-NAME respectively， and the effects of the above treatments on chilling tolerance， reactive oxygen species（ROS） levels and antioxidant defense system were analyzed in the cells under low temperature stress. The results showed that： （1）exogenous EBR treatment enhanced chilling tolerance in the suspension cultures and alleviated the inhibition of cell viability and aggravations of ion leakage and membrane lipid peroxidation induced by low temperature. The effects of SNP treatment on the above physiological measures were similar to those of EBR. （2）Application of PTIO or L-NAME in combination with EBR significantly decreased cell viability and increased ion leakage and membrane lipid peroxidation in C. bungeana suspension cultures under chilling stress compared with those of EBR treatment alone， suggesting that the block in NO signaling decreased the EBR-enhanced chilling tolerance. （3）EBR treatment further increased NO production and NOS activity in the suspension cells compared with those under chilling stress alone， whereas the EBR-induced NO signal was quenched by the addition of PTIO or L-NAME. （4）Both EBR and SNP obviously inhibited the increases in hydrogen peroxide（H2O2） content， superoxide radical（ O 2 · – ） production rate and hydroxyl radical （OH-）content caused by chilling， and remarkably enhanced the activities of ascorbate peroxidase（APX）， catalase（CAT）， glutathione reductase（GR）， peroxidase（POD） and superoxide dismutase（SOD） and contents of ascorbate （AsA） and glutathione（GSH） in the suspension cultured cells， thus alleviating oxidative injury caused by low temperature. However， PTIO and L-NAME blocked the protective effects of EBR. In conclusion， these results suggested that EBR-induced chilling tolerance in C. bungeana suspension cultured cells was through the promotion of NO accumulation by activating NOS activity. EBR might confer an increased tolerance to chilling stress by suppressing the accumulation of ROS caused by chilling and enhancing antioxidant defense system in the suspension cells， both of which were partially regulated by NO signal， resulting in the alleviation of chilling-induced oxidative damage and membrane lipid peroxidation. Thus， NOS-derived NO might be a downstream signaling molecule of EBR signal in C. bungeana suspension cultured cells under low temperature stress.
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 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.
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.
Handeliodendron bodinieri is an endangered species endemic in karst areas of southwest China. In order to explore the influence of soil gravel content on the growth and physiological characteristics of H. bodinieri seedlings in three consecutives growing seasons， annual H. bodinieri seedlings were used as experimental materials， different soil gravel content（0（control）， 20%， 40%， 60%， 80%） were set， and the growth， photosynthesis and physiological indicators of each group of seedlings were determined and evaluated in three consecutive growth seasons. The results showed that in the first growing season， when the soil gravel content was 60%， the net photosynthetic rate of the seedlings was significantly higher than that of the control group； When the soil gravel content was 40%， the growth rate of seedling diameter， leaf biomass， transpiration rate， stomatal conductance， soluble protein mass fraction， and superoxide dismutase（SOD） activity were significantly higher than those of the control group； The intercellular CO2 molar fraction and soluble sugar mass fraction of seedlings were significantly higher than those of the control group when the gravel content was greater than 20%； There was no significant difference in plant height growth rate， leaf area， root， stem， and total biomass between the control group and the control group. In the second growing season， when the soil gravel content was 60%， the transpiration rate and soluble protein mass fraction of H. bodinieri seedlings were significantly higher than those of the control group； When the soil gravel content was 40%， the SOD activity of the seedlings was significantly higher than the control group， and the stem biomass was significantly higher than the control group when the soil gravel content was 20%. The other indicators showed similar trends to the first growth season. With the extension of the growing season， in the third growing season， the growth rate of plant height and ground diameter， stem biomass， leaf area， stomatal conductance， SOD and POD activities of H. bodinieri seedlings reached the maximum when the soil gravel content was 60%， which was significantly higher than that of the control group； The net photosynthetic rate and intercellular CO2 concentration of seedlings reached the maximum when the soil gravel content was 40%， which was significantly higher than that of the control group. The comprehensive analysis showed that in the three consecutive growth seasons， the soil gravel content with the highest score of H. bodinieri seedlings was 40%， 40% and 60% respectively. For three consecutive growth seasons， seedlings grew best at 60% soil gravel content.
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 investigate whether there were differences in the results of leaf force-to-punch under different calibration methods and different puncture needle diameters， and the relationship between the results and leaf functional traits， 30 dicotyledonous species were selected to determine the punching force and the tearing force of the leaves and the functional traits of leaves under three puncture needle diameters of 2.0， 1.0 and 0.5 mm， respectively. The results showed that： （1）the leaf force-to-punch differed significantly（P<0.05） among the three different puncture needle diameters， for the same species when the method calibrated by perimeter， the difference between 0.5 mm and 1.0 mm was 76%， between 0.5 mm and 2.0 mm was 76%， and between 1.0 mm and 2.0 mm was 33%（P<0.05）； however， when calibrated by cross-sectional area， the difference was 66%， 56% and 30%（P<0.05） respectively. （2）There was no significant difference in leaf force to punch between the three puncture needle diameters under different calibration methods in the same life form， but there was significant differences（P<0.05） between herbs and different life form such as shrubs and trees， respectively， while the leaf force-to-punch of 0.5 mm diameter needles was greater than that of 1 and 2 mm needles. （3）Leaf force to punch was significantly positively correlated with leaf cuticle thickness， leaf thickness， and leaf tearing force（P<0.05）， and negatively correlated with specific leaf area（P<0.05）， and the correlation between punching force calibrated by needle circumference and leaf functional traits was stronger than that calibrated by cross-sectional area， whereas there was no significant difference in the correlation between leaf force to punch and leaf traits under the action of different diameters of puncture needles. Therefore， differences in both needle diameter and calibration methods produced differences in the results of leaf force to punch measurements. Differences in needle diameters did not affect the correlation between mechanical punching force and leaf functional traits， whereas differences in calibration methods affected the strength of the correlation between mechanical punching force and leaf functional traits. In conclusion， in the leaf force to punch research， selecting the appropriate calibration method and puncture needle diameter was conducive to improving the standardization and accuracy of the data， it was recommended that the two calibration methods based on the needle perimeter should be selected first， and among the three types of puncture needle diameter， 0.5 mm was selected to measure with small leaf area and dense and thin veins， and 2.0 mm was selected to measure with large leaf area and， dense and stiff veins.
To reveal the ecological adaptation mechanism of Quercus semicarpifolia in the subalpine zone of the Hengduan Mountains， the leaves and growing soil of eight plots were selected， and the C， N and P contents and their stoichiometric characteristics of leaves and growing substrate soil were measured， and the growth-limiting elements were determined. The ecological stoichiometry homeostasis model was used to determine the state of the alpine Quercus leaves. The soil C， N and P contents of the selected eight plots ranged from 38.86-70.19， 3.54-9.46 and 0.61-2.05 g?kg-1， with soil ω（C）∶ω（N） 5.65-16.07， ω（C）∶ω（P） 36.98-74.42 and ω（N）∶ω（P） 4.41-12.90， mean values were 9.48， 51.79 and 6.54， respectively. Leaf C， N and P contents ranged from 428.31-473.86， 21.22-31.68 and 2.21-3.68 g?kg-1， leaf ω（C）∶ω（N）， ω（C）∶ω（P）， and ω（N）∶ω（P） were 14.16-22.46， 121.41-215.86 and 6.99-12.84， with mean values of 17.36， 164.39 and 9.68， respectively. The alpine Quercus leaf N and P contents were higher than the global average. Leaf N and soil P， leaf N and soil ω（C）∶ω（N）， leaf ω（C）∶ω（P） and soil ω（N）∶ω（P）， leaf ω（C）∶ω（N） and soil ω（N）∶ω（P）， and leaf ω（C）∶ω（P） and leaf ω（N）∶ω（P） were highly significantly and positively correlated in each plot （P<0.01）. In addition，the leaf stoichiometric homeostasis index of alpine Quercus were probed in terms of 1/H absolute values， while 1/Hω（N） was -0.181-0.141， 1/Hω（P） was -1.255-1.206， and 1/H［ω（N）∶ω（P）］ was 0.391-0.960. The results indicated that each alpine Quercus 1/Hω（N） was in the homeostasis state， 1/H ω（P） and 1/H［ω（N）∶ω（P）］ were mostly in the weakly homeostasis state， weakly sensitive and sensitive state. Leaf ω（N）∶ω（P） ratio was less than or close to 16， illustrating that alpine Quercus in this region tended to be not deficient in both N and P elements. Alpine Quercus might overstore N and P elements to adapt to the changing external habitat， but still had a more conservative strategy for the use of external P elements. The alpine Quercus forests in this region had formed a good nutrient supply and return relationship with the soil in the long-term succession process， which had formed a relatively complete and stable subalpine forest ecosystem.
