Leaves are the main photosynthesis organ that directly determines crop yield and biomass.Dissecting the regulatory mechanism of leaf development is crucial for food security and ecosystem turn-over.Here,we identified ...Leaves are the main photosynthesis organ that directly determines crop yield and biomass.Dissecting the regulatory mechanism of leaf development is crucial for food security and ecosystem turn-over.Here,we identified the novel function of R2R3-MYB transcription factors CsRAXs in regulating cucumber leaf size and fruiting ability.Csrax5 single mutant exhibited enlarged leaf size and stem diameter,and Csrax1/2/5 triple mutant displayed further enlargement phenotype.Overexpression of CsRAX1 or CsRAX5 gave rise to smaller leaf and thinner stem.The fruiting ability of Csrax1/2/5 plants was significantly enhanced,while that of CsRAX5 overexpression lines was greatly weakened.Similarly,cell number and free auxin level were elevated in mutant plants while decreased in overexpression lines.Biochemical data indicated that CsRAX1/5 directly promoted the expression of auxin glucosyltransferase gene CsUGT74E2.Therefore,our data suggested that CsRAXs function as repressors for leaf size development by promoting auxin glycosylation to decrease free auxin level and cell division in cucumber.Our findings provide new gene targets for cucumber breeding with increased leaf size and crop yield.展开更多
Aims Leaf size and shape as objects of natural selection can play adaptive roles,and can change with the age of leaves.They can differ between sexes in dioecious species,and in most cases,females have larger leaves.Pr...Aims Leaf size and shape as objects of natural selection can play adaptive roles,and can change with the age of leaves.They can differ between sexes in dioecious species,and in most cases,females have larger leaves.Previous studies showed that sexes of Adriana tomentosa differed in their leaf lobing.In this study,we investigated whether there were other differences between sexes in leaf size,shape and ecophysiology,and if those differences were connected with adaptations and reproductive roles in the sexes of A.tomentosa.Methods Physical and chemical features of young and old leaves originating from female and male A.tomentosa plants growing in two disjunct populations in eastern Australia were measured.We determined leaf area,perimeter length,serration,circularity,aspect ratio(AR),roundness and the ecophysiological factors:specific leaf area,dry matter content,leaf moisture,relative water content,δ^(13)C,δ^(15)N isotope compositions,carbon and nitrogen contents and C:N ratio.Leaf lobing,the degree of lamina damage and the content of photosynthetic pigments were also determined.Important Findings In both populations studied,the sex of plants significantly influenced almost all parameters connected with leaf morphology such as area,perimeter length,circularity,AR and roundness.Contrary to expectations,males from both populations had a greater leaf area that was independent of leaf age.Male leaves were more lobed with a longer perimeter,but they were less elongated and less serrated.Only small differences between female and male leaves were observed for the ecophysiological factors.The degree of leaf damage differed between sexes but also with population.Differences between sexes in leaf area and shape were not compensated by measured ecophysiological factors.However,leaf area may be compensated by other ecophysiological mechanisms related to leaf morphology,because females had greater leaf serration in comparison to males despite the smaller leaf area.展开更多
Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have...Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have considerable genotypic and leaf morphological variations that have allowed them to inhabit wide environmental gradients. In this study, we analyzed variations in leaf morphological characteristics in 23 paper birch populations collected across Canada and grown in a greenhouse. Furthermore, we examined whether the variations in leaf morphological characteristics observed were related to the climate of the population’s origin. We found significant genotypic differences in all leaf morphological characteristics (p < 0.05) measured among the birch populations. Thus, we expected that the morphological variations in birch might be related to natural diversity in birch populations due to environmental differences at habitat origin. Principal component analysis (PCA) reduced thirteen leaf morphological variables to five principal components (PC) explaining 84.74% of the total variance in the original data. PCs accumulated with specific leaf area, petiole and leaf width were positively related to latitudinal, longitudinal, and elevational gradients at the population’s origin. Unpredictably, these PCs were significantly negatively correlated to precipitation and aridity index at the origin. Thus, we analyzed if correlations within leaf morphological characteristics had supported the birch populations to acclimate and produce unpredictable relations with the environment of origin. Our results showed that the populations originated in limited precipitation (during growing season) had large leaf width and petiole size but low leaf hairs on adaxial surface. Thus, all these leaf morphological features provide a basis for the birch to reduce water loss from leaves and balance water use efficiency in reduced precipitation. Furthermore, the leaf characteristics measured may also include phenotypic plasticity of the birch as an acclimation to the environment as in the greenhouse.展开更多
Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fa...Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses （i.e. poplar-crop integrated system, poplar plantation, and cropland）, from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes （5, 1 and 0. 01 mm, respectively） to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef＇s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags underthe same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna （3.31%）. The percentage of remaining litter mass was inversely related to the density of the soil fauna （P 〈 0.05） in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.展开更多
Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollu...Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chiuensis, Sophora japonica Ailanthus altissima, Syringa oblata and Prunus persica, had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicns and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM30 （particulate matter less than 10 μm in aerodynamic diameter; 98.4%） and PM2.5 （particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%） which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg（CO3）2, NaCI and 2CASO4. H2O, SiO2. CaCO3 and CaMg（CO3）2 mainly came from resuspension of road dust. 2CaSO4. H2O was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.展开更多
Insect herbivory is ubiquitous in various ecosystems,and directly influences the growth and survival of individual plants,especially during their vulnerable early life stages like the seedling phase.This,in turn,exert...Insect herbivory is ubiquitous in various ecosystems,and directly influences the growth and survival of individual plants,especially during their vulnerable early life stages like the seedling phase.This,in turn,exerts a significant influence on forest community diversity and structure,as well as ecosystem function and stability.Notable variation in herbivory has been detected both among and within plant species.For decades,many hypotheses have been proposed to explain such variations,including both biotic and abiotic variables.However,most studies have considered only one or several of these hypotheses by focusing on a few potential variables,and their results were usually inconsistent;thus,the factors driving herbivory remain unclear.In this study,we examined leaf herbivory by insects of woody species seedlings in a subtropical forest in southwestern China over two seasons.In total,24 potential variables that represented abiotic resource availability,characters of individual seedlings,conspecific and heterospecific species,and the whole seedling community were selected to test several commonly discussed alternative herbivory hypotheses.Overall,our findings showed that the plant apparency hypothesis was more supported than the other hypotheses in explaining insect seedling herbivory.Our results further indicated that the mechanisms and causes of insect herbivory are complex,multifactorial,species-specific and vary with seasons,indicating that there may be no uniform rules in explaining herbivory for all seedlings.Consequently,such complexity may play an important role in promoting species coexistence and biodiversity maintenance in seedling communities,which may further translate into the following generation of saplings or even adult communities.Changes in the community of insect herbivores and/or variables influencing insect herbivory,may disrupt stability of the original seedling community,thus affecting the regeneration and development of the entire forest community.Therefore,we suggest that issues related to insect herbivory should be considered when developing forest management and conservation.展开更多
Stress in plants refers to adverse changes in their functioning.The occurrence and intensity of a stress can be assessed by alterations in plant traits,termed stress indicators.The ultimate goal of this study was to t...Stress in plants refers to adverse changes in their functioning.The occurrence and intensity of a stress can be assessed by alterations in plant traits,termed stress indicators.The ultimate goal of this study was to test whether six morpho-physiological plant traits,frequently used as stress indicators,respond consistently across species to various environmental stressors,with the aim of detecting universal stress indicators in forest tree species.We examined changes in vertical increment,leaf/needle size,shoot length,needle longevity,photosynthetic efficiency and fluctuating asymmetry in three common European tree species,mountain birch(Betula pubescens var.pumila),Norway spruce(Picea abies)and Scots pine(Pinus sylvestris)along three environmental gradients(elevation,pollution and seashore)from forests to stressful open environments.Data were collected in 2003,2004 and 2005 from 297 trees growing naturally across 36 sites in north-western Russia.Fluctuating asymmetry was the only trait that did not vary among sites with differing levels of environmental stress.Leaf/needle size and shoot length occasionally changed along stress gradients,but the magnitude and direction of these changes differed by gradient type and species,resulting in no significant overall stress effect for either trait.In contrast,photosynthetic efficiency,vertical increment and needle longevity consistently decreased from low-stress to high-stress sites.The overall effect was significant for each of these three traits despite the magnitudes of these decreases differed depending on the gradient type and location,species,study year and individual tree.Replication at spatial,temporal and taxonomic levels ensured the robustness and reliability of our results that photosynthetic efficiency,vertical growth and needle longevity reliably captured a general stress syndrome and may serve as stress indicators in forest species.展开更多
叶大小与小枝大小关系反映了植物对木质部同其所支持的光合作用面积的配置比例关系,不同生境中其生长关系的变异体现植物对异质环境的适应方式。在祁连山北坡高寒草地,利用ArcGIS建立研究区域的数字高程模型(DEM),并提取样地坡向数据,...叶大小与小枝大小关系反映了植物对木质部同其所支持的光合作用面积的配置比例关系,不同生境中其生长关系的变异体现植物对异质环境的适应方式。在祁连山北坡高寒草地,利用ArcGIS建立研究区域的数字高程模型(DEM),并提取样地坡向数据,采用标准化主轴估计(standardized major axis estimation,SMA)方法,研究了不同坡向狼毒(Stellera chamaejasme)种群叶与枝的生长。结果表明:随着坡向由南坡向东坡、西坡和北坡转变,狼毒叶面积、叶片数和枝长度均呈逐渐增加趋势;狼毒叶片数、叶面积与枝长度均呈异速生长关系,枝长度增加的速度大于叶片数和叶面积增加的速度;随着坡向由北坡向东坡、西坡和南坡转变,狼毒叶片数与枝长度的异速斜率逐渐增大,叶面积与枝长度的异速斜率逐渐减小。生境对狼毒枝条与叶片的生长具有显著影响,北坡具有更适宜狼毒生长的生境条件,南坡土壤水分匮乏等不利影响使狼毒枝条与叶片变小,并且单位长度枝条支持更多的叶片。展开更多
Leaf-size classes of 337 vascular plants in Quercus mongolica community in northeast, China were analyzed according to Raunkiaer system. The dominant type was microphyll which percentage is 45.4%,followed by compound ...Leaf-size classes of 337 vascular plants in Quercus mongolica community in northeast, China were analyzed according to Raunkiaer system. The dominant type was microphyll which percentage is 45.4%,followed by compound leaf (23.1%),mesophyll ( 22.6%),nanophyll (6.8%),macrophyll (0.9%),aphyllous (0.9%),leptophyll ( 0.3%).The leaves edges of 337 plants were investigated and the percentage of entire leaves plants is 22.3%.Leaf-size classes spectra of trees,shrubs and herbs were figured out.The mesophyll ratio in trees was higher than that in shrubs and herbs.The mesophyll ratio in shrubs was the lowest.Different sites had different leaf-size classes spectra.Microphyll also was the dominant type in every site.No significant relationships were found between leaf-size classes spectra and latitude and altitued.展开更多
植物不同等级的叶脉承担着不同的功能,叶脉密度与叶大小的异速生长模式有助于揭示植物表型可塑性形成机制。利用Arc GIS建立研究区域的数字高程模型(DEM),采用标准化主轴估计(standardized major axis estimation,SMA)方法,研究了兰州...植物不同等级的叶脉承担着不同的功能,叶脉密度与叶大小的异速生长模式有助于揭示植物表型可塑性形成机制。利用Arc GIS建立研究区域的数字高程模型(DEM),采用标准化主轴估计(standardized major axis estimation,SMA)方法,研究了兰州市北山不同坡向人工林刺槐(Robinia pseudoacacia)一级和二级叶脉密度与叶大小的关系。结果表明:随坡向由北坡向东坡、南坡和西坡转变,植被群落的郁闭度、高度和土壤含水量呈现先减小后增大趋势,刺槐的单叶面积、比叶面积和叶片偏心率(eccentricity)呈先减小后增大趋势,刺槐叶片的一级和二级叶脉密度呈先增大后减小趋势;4个坡向刺槐一级叶脉密度与叶面积呈显著的负相关关系(P<0.05),二级叶脉密度与叶面积呈极显著负相关关系(P<0.01),斜率均显著大于-1。刺槐叶大小与不同等级叶脉密度权衡关系的坡向差异,是植物对异质性生境适应的结果。展开更多
基金supported by grants from the National Natural Science Foundation of China[32025033,31930097 and 32372699]Pinduoduo-China Agricultural University Research Fund[PC2023B01002].
文摘Leaves are the main photosynthesis organ that directly determines crop yield and biomass.Dissecting the regulatory mechanism of leaf development is crucial for food security and ecosystem turn-over.Here,we identified the novel function of R2R3-MYB transcription factors CsRAXs in regulating cucumber leaf size and fruiting ability.Csrax5 single mutant exhibited enlarged leaf size and stem diameter,and Csrax1/2/5 triple mutant displayed further enlargement phenotype.Overexpression of CsRAX1 or CsRAX5 gave rise to smaller leaf and thinner stem.The fruiting ability of Csrax1/2/5 plants was significantly enhanced,while that of CsRAX5 overexpression lines was greatly weakened.Similarly,cell number and free auxin level were elevated in mutant plants while decreased in overexpression lines.Biochemical data indicated that CsRAX1/5 directly promoted the expression of auxin glucosyltransferase gene CsUGT74E2.Therefore,our data suggested that CsRAXs function as repressors for leaf size development by promoting auxin glycosylation to decrease free auxin level and cell division in cucumber.Our findings provide new gene targets for cucumber breeding with increased leaf size and crop yield.
基金supported by the Department of Education and Training,Australian Government(Endeavour Research Fellowship,2017 to M.R.),the University of New England in Armidale,Australia and the Institute of Dendrology,Polish Academy of Sciences,Poland.
文摘Aims Leaf size and shape as objects of natural selection can play adaptive roles,and can change with the age of leaves.They can differ between sexes in dioecious species,and in most cases,females have larger leaves.Previous studies showed that sexes of Adriana tomentosa differed in their leaf lobing.In this study,we investigated whether there were other differences between sexes in leaf size,shape and ecophysiology,and if those differences were connected with adaptations and reproductive roles in the sexes of A.tomentosa.Methods Physical and chemical features of young and old leaves originating from female and male A.tomentosa plants growing in two disjunct populations in eastern Australia were measured.We determined leaf area,perimeter length,serration,circularity,aspect ratio(AR),roundness and the ecophysiological factors:specific leaf area,dry matter content,leaf moisture,relative water content,δ^(13)C,δ^(15)N isotope compositions,carbon and nitrogen contents and C:N ratio.Leaf lobing,the degree of lamina damage and the content of photosynthetic pigments were also determined.Important Findings In both populations studied,the sex of plants significantly influenced almost all parameters connected with leaf morphology such as area,perimeter length,circularity,AR and roundness.Contrary to expectations,males from both populations had a greater leaf area that was independent of leaf age.Male leaves were more lobed with a longer perimeter,but they were less elongated and less serrated.Only small differences between female and male leaves were observed for the ecophysiological factors.The degree of leaf damage differed between sexes but also with population.Differences between sexes in leaf area and shape were not compensated by measured ecophysiological factors.However,leaf area may be compensated by other ecophysiological mechanisms related to leaf morphology,because females had greater leaf serration in comparison to males despite the smaller leaf area.
文摘Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have considerable genotypic and leaf morphological variations that have allowed them to inhabit wide environmental gradients. In this study, we analyzed variations in leaf morphological characteristics in 23 paper birch populations collected across Canada and grown in a greenhouse. Furthermore, we examined whether the variations in leaf morphological characteristics observed were related to the climate of the population’s origin. We found significant genotypic differences in all leaf morphological characteristics (p < 0.05) measured among the birch populations. Thus, we expected that the morphological variations in birch might be related to natural diversity in birch populations due to environmental differences at habitat origin. Principal component analysis (PCA) reduced thirteen leaf morphological variables to five principal components (PC) explaining 84.74% of the total variance in the original data. PCs accumulated with specific leaf area, petiole and leaf width were positively related to latitudinal, longitudinal, and elevational gradients at the population’s origin. Unpredictably, these PCs were significantly negatively correlated to precipitation and aridity index at the origin. Thus, we analyzed if correlations within leaf morphological characteristics had supported the birch populations to acclimate and produce unpredictable relations with the environment of origin. Our results showed that the populations originated in limited precipitation (during growing season) had large leaf width and petiole size but low leaf hairs on adaxial surface. Thus, all these leaf morphological features provide a basis for the birch to reduce water loss from leaves and balance water use efficiency in reduced precipitation. Furthermore, the leaf characteristics measured may also include phenotypic plasticity of the birch as an acclimation to the environment as in the greenhouse.
基金supported by the National Basic Research Program of China(973 Program,2012CB416904)partially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses （i.e. poplar-crop integrated system, poplar plantation, and cropland）, from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes （5, 1 and 0. 01 mm, respectively） to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef＇s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags underthe same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna （3.31%）. The percentage of remaining litter mass was inversely related to the density of the soil fauna （P 〈 0.05） in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.
基金The National Natural Science Foundation of China (No. 30570338) the Natural Science Foundation of Beijing (No. 6053026) andthe Ministry of Education, China(No. 20040027020).
文摘Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chiuensis, Sophora japonica Ailanthus altissima, Syringa oblata and Prunus persica, had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicns and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM30 （particulate matter less than 10 μm in aerodynamic diameter; 98.4%） and PM2.5 （particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%） which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg（CO3）2, NaCI and 2CASO4. H2O, SiO2. CaCO3 and CaMg（CO3）2 mainly came from resuspension of road dust. 2CaSO4. H2O was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.
基金supported by the National Natural Science Foundation of China(Nos.32171533 and 31971444)Anhui Provincial Natural Science Foundation(No.2208085J28)。
文摘Insect herbivory is ubiquitous in various ecosystems,and directly influences the growth and survival of individual plants,especially during their vulnerable early life stages like the seedling phase.This,in turn,exerts a significant influence on forest community diversity and structure,as well as ecosystem function and stability.Notable variation in herbivory has been detected both among and within plant species.For decades,many hypotheses have been proposed to explain such variations,including both biotic and abiotic variables.However,most studies have considered only one or several of these hypotheses by focusing on a few potential variables,and their results were usually inconsistent;thus,the factors driving herbivory remain unclear.In this study,we examined leaf herbivory by insects of woody species seedlings in a subtropical forest in southwestern China over two seasons.In total,24 potential variables that represented abiotic resource availability,characters of individual seedlings,conspecific and heterospecific species,and the whole seedling community were selected to test several commonly discussed alternative herbivory hypotheses.Overall,our findings showed that the plant apparency hypothesis was more supported than the other hypotheses in explaining insect seedling herbivory.Our results further indicated that the mechanisms and causes of insect herbivory are complex,multifactorial,species-specific and vary with seasons,indicating that there may be no uniform rules in explaining herbivory for all seedlings.Consequently,such complexity may play an important role in promoting species coexistence and biodiversity maintenance in seedling communities,which may further translate into the following generation of saplings or even adult communities.Changes in the community of insect herbivores and/or variables influencing insect herbivory,may disrupt stability of the original seedling community,thus affecting the regeneration and development of the entire forest community.Therefore,we suggest that issues related to insect herbivory should be considered when developing forest management and conservation.
基金supported by the Research Council(formerly Academy)of Finland(projects 122133,214824,362731,and researcher posts of M.V.Kozlov)EC through the BALANCE project carried out under contract EVK2-2002-00169,and the University of Turku。
文摘Stress in plants refers to adverse changes in their functioning.The occurrence and intensity of a stress can be assessed by alterations in plant traits,termed stress indicators.The ultimate goal of this study was to test whether six morpho-physiological plant traits,frequently used as stress indicators,respond consistently across species to various environmental stressors,with the aim of detecting universal stress indicators in forest tree species.We examined changes in vertical increment,leaf/needle size,shoot length,needle longevity,photosynthetic efficiency and fluctuating asymmetry in three common European tree species,mountain birch(Betula pubescens var.pumila),Norway spruce(Picea abies)and Scots pine(Pinus sylvestris)along three environmental gradients(elevation,pollution and seashore)from forests to stressful open environments.Data were collected in 2003,2004 and 2005 from 297 trees growing naturally across 36 sites in north-western Russia.Fluctuating asymmetry was the only trait that did not vary among sites with differing levels of environmental stress.Leaf/needle size and shoot length occasionally changed along stress gradients,but the magnitude and direction of these changes differed by gradient type and species,resulting in no significant overall stress effect for either trait.In contrast,photosynthetic efficiency,vertical increment and needle longevity consistently decreased from low-stress to high-stress sites.The overall effect was significant for each of these three traits despite the magnitudes of these decreases differed depending on the gradient type and location,species,study year and individual tree.Replication at spatial,temporal and taxonomic levels ensured the robustness and reliability of our results that photosynthetic efficiency,vertical growth and needle longevity reliably captured a general stress syndrome and may serve as stress indicators in forest species.
文摘叶大小与小枝大小关系反映了植物对木质部同其所支持的光合作用面积的配置比例关系,不同生境中其生长关系的变异体现植物对异质环境的适应方式。在祁连山北坡高寒草地,利用ArcGIS建立研究区域的数字高程模型(DEM),并提取样地坡向数据,采用标准化主轴估计(standardized major axis estimation,SMA)方法,研究了不同坡向狼毒(Stellera chamaejasme)种群叶与枝的生长。结果表明:随着坡向由南坡向东坡、西坡和北坡转变,狼毒叶面积、叶片数和枝长度均呈逐渐增加趋势;狼毒叶片数、叶面积与枝长度均呈异速生长关系,枝长度增加的速度大于叶片数和叶面积增加的速度;随着坡向由北坡向东坡、西坡和南坡转变,狼毒叶片数与枝长度的异速斜率逐渐增大,叶面积与枝长度的异速斜率逐渐减小。生境对狼毒枝条与叶片的生长具有显著影响,北坡具有更适宜狼毒生长的生境条件,南坡土壤水分匮乏等不利影响使狼毒枝条与叶片变小,并且单位长度枝条支持更多的叶片。
文摘Leaf-size classes of 337 vascular plants in Quercus mongolica community in northeast, China were analyzed according to Raunkiaer system. The dominant type was microphyll which percentage is 45.4%,followed by compound leaf (23.1%),mesophyll ( 22.6%),nanophyll (6.8%),macrophyll (0.9%),aphyllous (0.9%),leptophyll ( 0.3%).The leaves edges of 337 plants were investigated and the percentage of entire leaves plants is 22.3%.Leaf-size classes spectra of trees,shrubs and herbs were figured out.The mesophyll ratio in trees was higher than that in shrubs and herbs.The mesophyll ratio in shrubs was the lowest.Different sites had different leaf-size classes spectra.Microphyll also was the dominant type in every site.No significant relationships were found between leaf-size classes spectra and latitude and altitued.
