Aroma(volatile)compounds play important ecological functions in plants,and also contribute to the quality of plant-derived foods.Moreover,chiral aroma compounds affect their functions in plants and lead to different f...Aroma(volatile)compounds play important ecological functions in plants,and also contribute to the quality of plant-derived foods.Moreover,chiral aroma compounds affect their functions in plants and lead to different flavor quality properties.Formations of chiral aroma compounds are due to the presence of enzymes producing these compounds in plants,which are generally involved in the final biosynthetic step of the aroma compounds.Here,we review recent progress in research on the plant-derived enzymes producing chiral aroma compounds,and their changes in response to environmental factors.The chiral aroma enzymes that have been reported produce(R)-linalool,(S)-linalool,(R)-limonene,and(S)-limonene,etc.,and these enzymes are found in various plant species.We also discuss the origins of enantioselectivity in the plant-derived enzymes producing chiral aroma compounds and summarize the potential use of plants containing enzymes producing chiral aroma compounds for producing chiral flavors/fragrances.展开更多
Climate change is forecast to increase the frequency of extreme hot temperatures and dryer days and is anticipated to have profound impacts on the global carbon budget.Droughts are expected to alter soil respiration(R...Climate change is forecast to increase the frequency of extreme hot temperatures and dryer days and is anticipated to have profound impacts on the global carbon budget.Droughts are expected to alter soil respiration(R_(s))rates,but the scarcity of data preclude a reliable estimate of this response and its future trajectory.A field experiment using an automated soil respiration machinery(LI-8100A)was conducted in a natural forest and a plantation during a dry period in the Philippines,with the goal of quantifying Rsrates and their relationship with soil temperature and moisture,and air temperature.The natural forest(5.81μmol m^(-2)s^(-1))exhibited significantly higher Rsrates(p<0.0001)compared with the plantation(1.82μmol m^(-2)s^(-1))and control(3.23μmol m^(-2)s^(-1)).Rsrates showed significant negative relationships with air(-0.71)and soil temperatures(-0.62),indicating that as temperatures increase,the R_(s)rates decrease.In contrast,the R_(s)rates exhibited a significant positive relationship with soil moisture(0.65).Although the low R_(s)rates in the plantation and high Rsrates in the natural forest are indicators of sensitivities of these two types of tropical forests to warm,dry soil,this observation is only conclusive during the dry period,but not necessarily during wet periods.Further studies are needed to determine the trend of Rsrates during wet periods,considering different site conditions and types of vegetation.展开更多
Lake Urmia,Northwest Iran,has confronted a drying procedure in recent years with losing 90%of its water body.The authorities concerned about desertification processes and possible dust events throughout the region.In ...Lake Urmia,Northwest Iran,has confronted a drying procedure in recent years with losing 90%of its water body.The authorities concerned about desertification processes and possible dust events throughout the region.In this regard,the Iranian Natural Resources and Watershed Management Organization has taken ecological measures to plant vegetation using salt cedar(Tamarix ramosissima Ledeb.)shrubs to combat desertification.This study aimed to investigate the vegetation and soil characteristics of natural and plantation stands of salt cedar on the western shores of Lake Urmia.To this end,7 transects were randomly selected with 15 shrubs in natural stands,and 7 transects were randomly selected with 15 shrubs in the plantation parts along the planting rows.Then,vegetative characteristics were examined.Also,soil samples were taken from the vicinity of the shrubs.The results indicated that there was no significant difference between the mean diameter at breast height(DBH)of salt cedar in natural sites.There was a significant difference between the mean number of sprouts per sprout-clumps,mean crown diameter,collar diameter,total height,and also between mean crown diameter and freshness of shrubs among different sites(P<0.05).It was also found that soil variables,such as clay content,organic matter,electrical conductivity(EC),Na^(+),specific absorption rate(SAR),Cl^(-),SO_(4)^(2-),Na^(+),K^(+),and PO_(4)^(2-) are the most significant variable parameters between studied sites.As the results shown,the values of EC,SAR,Na^(+),and Cl^(-)are 6 times higher in the planted stands than in the natural stands of T.ramosissima.Also,the colonization of T.ramosissima in the planted stands is unsuccessful by dramatic drop in the total height and average diameter.Considering the role of soil characteristics in explaining the variance of data and site separation,it seems that these indicators can be applied in executive plans as important indicators to identify suitable planting sites for combating desertification.展开更多
Due to considerable deforestation in North Korea,there is a need to plan forest restoration programs based on scientific forest management.In this study,a methodology was developed for estimating the site index values...Due to considerable deforestation in North Korea,there is a need to plan forest restoration programs based on scientific forest management.In this study,a methodology was developed for estimating the site index values of six major tree species and the forest productivity potential.The site index values of these tree species were derived in South Korea using the Chapman-Richards equation.These values were used with data from the 6th National Forest Inventory,which included 20 types of edaphic,topographic,and climatic factors,and random forest analysis—a widely used machine learning technique for spatial prediction—to develop a new model for estimating the site index values of these species across South Korea.The prediction accuracy of this model was evaluated using the root mean square error.The results show that the prediction accuracy was high,with a root mean square error of~1m.Moreover,the importance of the variables related to climate and geography was generally high.The proposed site index estimation model for six tree species was applied across North Korea,and its effectiveness tested by comparing the estimated values with those reported in literature from North Korea.The differences between the model outputs and recorded data in the northern alpine regions were presumably due to the lack of data for high-altitude regions in South Korea.This model is based on the determination of the suitability of tree species in restoration efforts.Therefore,it can contribute to the evaluation of forest productivity in North Korea and may help plan efficient forest restoration programs.展开更多
To evaluate the relationships among clones and open pollinated families from the same plus trees and to select elite breeding materials,growth,and wood characteristics of 33-year-old Pinus korainsis clones and familie...To evaluate the relationships among clones and open pollinated families from the same plus trees and to select elite breeding materials,growth,and wood characteristics of 33-year-old Pinus korainsis clones and families were measured and analyzed.The results show that growth and wood characters varied significantly.The variation due to clonal effects was higher than that of family effects.The ratio of genetic to phenotypic coefficient of variation of clones in growth and wood traits was above 90%,and the repeatability of these characteristics was more than 0.8,whereas the ratio of genetic to phenotypic coefficient of variation of families was above 90%.The broad-sense heritability of all characteristics exceeded 0.4,and the narrow-sense family heritability of growth traits was less than 0.3.Growth characteristics were positively correlated with each other,but most wood properties were weakly correlated in both clones and families.Fiber length and width were positively correlated between clones and families.Using the membership function method,eleven clones and four families were selected as superior material for improved diameter growth and wood production,and two families from clonal and open-pollinated trees showed consistently better performance.Generally,selection of the best clones is an effective alternative to deployment of families as the repeatability estimates from clonal trees were higher than narrow-sense heritability estimates from open pollinated families.The results provide valuable insight for improving P.koraiensis breeding programs and subsequent genetic improvement.展开更多
Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection....Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection. However, significant knowledge gaps exist regarding when and where to plant trees. This article reports on a revegetation trial undertaken in St Elizabeth, Mahdia, Guyana, to assess the survival and RGR (Relative Growth Rate) of three native woody trees and shrubs planted within three years old Acacia mangium Willd trees pruned and unpruned blocks. ANOVA (Analysis of Variance) for a completely randomized block design with four blocks, two pruned and two unpruned, within A. mangium plots. Biochar treatment was added to the plants during transplanting. Thirty-six (36) wildlings of Humiria balsamifera (Aublet.) (Tauroniro), Goupia glabra Aublet (Kabukalli), and Vismia guianensis (Aublet.) Choisy (Bloodwood) were collected and raised in a tree nursery for two weeks. The native plants were transplanted 3 m apart, survival observations and each seedling’s initial height and diameter were measured and recorded. After the experiment, 13% of seedlings from a population of 720 had died, with the highest mortality being experienced at the 92 days of the experiment (t ≤ 122 days). While the overall survival rates were high, emphasizing the importance of field trials on native and exotic species in different environments is essential to fill the knowledge gaps on suitable species for restoration in degraded areas with other land use histories.展开更多
The spatial interpolation for soil texture does not necessarily satisfy the constant sum and nonnegativity constraints. Meanwhile, although numeric and categorical variables have been used as auxiliary variables to im...The spatial interpolation for soil texture does not necessarily satisfy the constant sum and nonnegativity constraints. Meanwhile, although numeric and categorical variables have been used as auxiliary variables to improve prediction accuracy of soil attributes such as soil organic matter, they (especially the categorical variables) are rarely used in spatial prediction of soil texture. The objective of our study was to comparing the performance of the methods for spatial prediction of soil texture with consideration of the characteristics of compositional data and auxiliary variables. These methods include the ordinary kriging with the symmetry logratio transform, regression kriging with the symmetry logratio transform, and compositional kriging (CK) approaches. The root mean squared error (RMSE), the relative improvement value of RMSE and Aitchison's distance (D_A) were all utilized to assess the accuracy of prediction and the mean squared deviation ratio was used to evaluate the goodness of fit of the theoretical estimate of error. The results showed that the prediction methods utilized in this paper could enable interpolation results of soil texture to satisfy the constant sum and nonnegativity constraints. Prediction accuracy and model fitting effect of the CK approach were better, suggesting that the CK method was more appropriate for predicting soil texture. The CK method is directly interpolated on soil texture, which ensures that it is optimal unbiased estimator. If the environment variables are appropriately selected as auxiliary variables, spatial variability of soil texture can be predicted reasonably and accordingly the predicted results will be satisfied.展开更多
Jackfruit is cross-pollinated and mostly seed propagated, a wide range of variation exists in fruit quality. With the development of efficient vegetative propagation methods, excellent genotypes selected from these se...Jackfruit is cross-pollinated and mostly seed propagated, a wide range of variation exists in fruit quality. With the development of efficient vegetative propagation methods, excellent genotypes selected from these seed propagated seedlings will gradually replace other genotypes in jackfruit producing areas. In this study, genetic diversity of 50 jackfruit accessions from three provinces in China was analyzed based on amplified fragment length polymorphic (AFLP) markers. A total of 320 unambiguous bands were produced by eight primer combinations, and 65 (20.3%) of them were polymorphic. Genetic similarity coefficients ranged from 0 to 0.9841, with an average of 0.5000, indicating a moderate genetic diversity in this collection. The dendrogram derived by unweighted pair group method with arithmetic mean algorithm (UPGMA) analysis revealed five groups, and no correlation between genetic relationship and geographical origin were found. Accessions of soft and firm flesh type were not clustered into distinct groups, neither could yearly bearing once, or twice fruit accessions. This study has provided useful information for collection and preservation of jackfruit germplasm worldwide.展开更多
Water deficit in arid and semiarid regions affects whole-plant sap flow and leaf-level water relations. The objectives of this study were to clarify how sap flow of Calligonum arborescens responds to different drought...Water deficit in arid and semiarid regions affects whole-plant sap flow and leaf-level water relations. The objectives of this study were to clarify how sap flow of Calligonum arborescens responds to different drought stress conditions and to understand its acclimation mechanism to drought environments. A field experiment was conducted for C. arborescens during the growing season to evaluate the effects of deficit irrigation on the daily and seasonal variations of trunk sap flow in the shelterbelt along the Tarim Desert Highway, Xinjiang, China. Three different water regimes (2,380, 1,960 and 1,225 m3 /hm2 ) were applied at different stages of plant growth. From 1 May to 30 October 2007, a heat-balance stem flow gauge was used to monitor the sap flow dynamics of C. arborescens under different water regimes. Atmospheric evaporation demand and soil moisture conditions for differentially irrigated C. arborescens were also monitored. The result showed that sap flow exhibited a clear diurnal pattern regardless of treatments; the diurnal patterns of sap flow and vapour pressure deficit were very similar under different water regimes and growing seasons, while the slope of the linear regression of this correlation confirmed an increasing water regime. The sap flow decreased under reduced water regimes and there was nocturnal sap flow regardless of water regimes, which was mainly contributed to nocturnal transpiration and water recharge. The sap flow peaked before midnight and dropped afterwards with obviously higher values in summer than in other seasons. It is speculated that the water consumption of C. arborescens during the day can be supplemented through the sap flow at night, which increased with increasing irrigation amount. Net radiation was the most significant correlated factor that influenced sap flow velocity and transpiration under different water regimes (R2 >0.719). Compared with the commonly practiced water regime, the growth of C. arborescens was significantly slower in the stress deficit irrigation, but not significantly different from that in the moderate deficit irrigation. The moderate deficit irrigation would not affect the stability of the shelterbelt and was a more efficient use of water resources compared with the current watering amount.展开更多
The growth traits(tree height, diameter at breast height, and stem straightness degree) and wood properties[wood density(WD), fiber length, fiber width, ash content(AC), lignin content, cellulose content, hemicellulos...The growth traits(tree height, diameter at breast height, and stem straightness degree) and wood properties[wood density(WD), fiber length, fiber width, ash content(AC), lignin content, cellulose content, hemicellulose content(HEC), and holocellulose content] of 208 26-yearold Larix olgensis clones were analyzed. Except for WD and AC, there were significant differences(p \ 0.01) for all traits among clones. The phenotypic coefficient of variation and repeatability of all traits were 9.34–35.33%and 0.218–0.930, respectively. Tree height and diameter at breast height showed significant positive correlation;however, the correlation coefficients among growth characteristics and wood properties were mostly not significant.Ten clones(L70, L56, L82, L90, L59, L91, L61, L92, L86,and L64) were selected as excellent clones under a selection rate of 5%, using tree height, diameter at breast height,and stem straightness degree as evaluation indexes, providing genetic gains of 28.69, 17.96, and 0.67%, respectively. Ten clones(L88, L305, L59, L66, L253, L304,L277, L298, L248, and L293) were selected as excellent clones using wood properties as an evaluation index, with a selection rate of 5%, providing genetic gains in WD, fiber length, fiber width, cellulose content, and HEC of 4.14,3.64, 9.28, 6.77, and 9.61%, respectively. This study provides a theoretical basis for selecting excellent L. olgensis clones.展开更多
Siberian Pine(Pinus sibirica) is an ecologically and economically important species in pristine forests throughout northern Russia. Four provenances of P. sibirica were introduced from Mongolia and Russia to the Great...Siberian Pine(Pinus sibirica) is an ecologically and economically important species in pristine forests throughout northern Russia. Four provenances of P. sibirica were introduced from Mongolia and Russia to the Greater Xing'an Range(the Daxing'anling), northeast China in 1993. The aim of this research was to study genetic variation and selection of the introduced four Pinus sibirica provenances. Heights(H), basal diameters(BD), survival rates(SR) and crown lengths(CL) of different families were measured as primary outcomes in different growth years. Results of data analyses demonstrated high coefficients of phenotypic variation(PCV) and heritability(H2) for H, BD and CL at 18 years after introduction. PCV and H2 increased with age. Correlations of growth traits between any two growth years were all significantly positive, but the correlation coefficient was smaller when the growth year interval was larger. Correlations between H and the original environment factors decreased gradually, indicating that with long-term subsistence in the new environment, the influence of the source environment declined. Colligation of multiple traits to estimate provenances showed that Novosibirsk, Tomsk, and Altai Mountains had higher survival rates and biomass, and proved more suitable for introduction and plantation in the Greater Xing'an Range in China.展开更多
Early selection is an important method to shorten the breeding cycle for tree species, which may differ in the time for early selection.To evaluate the early selected time for Larix kaempferi, tree height and diameter...Early selection is an important method to shorten the breeding cycle for tree species, which may differ in the time for early selection.To evaluate the early selected time for Larix kaempferi, tree height and diameter at breast height of 57 L.kaempferi clones were measured over many different growth years.The results indicated that, except for age × clone interaction for diameter at breast height(P = 0.741), there were significant differences among all variation sources(P < 0.01).The coefficient of phenotypic variation ranged from 14.89 to 35.65%for height and from 19.17 to 23.86% for diameter at breast height in different growth years.The repeatability of height and of diameter at breast height among clones was high,ranging from 0.6181 to 0.8531(height) and from 0.8443 to0.8497(diameter at breast height), in different growth years.There were significant positive correlations between all pairs of growth traits except between height in the 2 nd growth year and height in the 30 th growth year; and between height in the 2 nd growth year × diameter at breast height in the 30 th growth year.With a comprehensive evaluation method and a selection ratio of 10%, L65,L1, L62, L9, L15, and L78 were selected as excellent clones in the 30 th growth year.Their average values of height and diameter at breast height were 9.81 and 16.57%higher than the overall average, representing genetic gains of 6.46 and 13.99%, respectively.This study provides a theoretical foundation for the genetic improvement of L.kaempferi.展开更多
We evaluated the spatial and temporal patterns of forest fires in two fire seasons(March to June and September to November) from 1996 to 2010 in Jilin Province,China,using the Canadian Forest Fire Weather Index System...We evaluated the spatial and temporal patterns of forest fires in two fire seasons(March to June and September to November) from 1996 to 2010 in Jilin Province,China,using the Canadian Forest Fire Weather Index System.Fire data were obtained from the Provincial Fire Agency,and historical climate records of daily weather observations were collected from 36 weather stations in Jilin and its neighboring provinces.A linear regression model was used to analyze linear trends between climate and fire weather indices with time treated as an independent variable.Correlation analysis was used to detect correlations between fire frequency,areas burned,and fire weather indices.A thin-plate smooth spline model was used to interpolate the point data of 36 weather stations to generate a surface covering the whole province.Our analyses indicated fire frequency and areas burned were significantly correlated with fire weather indices.Overall,the Canadian Forest Fire Weather Index System appeared to be work well for determining the fire danger rating in Jilin Province.Also,our analyses indicated that in the forthcoming decades,the overall fire danger in March and April should decrease across the province,but the chance of a large fire in these months would increase.The fire danger in the fall fire season would increase in the future,and the chance of large fire would also increase.Historically,because most fires have occurred in the spring in Jilin Province,such a shift in the future fire danger between the two fire seasons would be beneficial for the province's fire management.展开更多
Forest fires caused by natural forces or human activities are one of the major natural risks in Northeast China.The incidence and spatial distribution of these fires vary over time and across the forested areas in Jil...Forest fires caused by natural forces or human activities are one of the major natural risks in Northeast China.The incidence and spatial distribution of these fires vary over time and across the forested areas in Jilin Province,Northeast China.In this study,the incidence and distribution of 6519 forest fires from 1969 to 2013 in the province were investigated.The results indicated that the spatiotemporal distribution of the burnt forest area and the fire frequency varied significantly by month,year,and region.Fire occurrence displayed notable temporal patterns in the years after forest fire prevention measures were strictly implemented by the provincial government.Generally,forest fires in Jilin occurred in months when stubble and straw were burned and human activities were intense during traditional Chinese festivals.Baishan city,Jilin city,and Yanbian were defined as fire-prone regions for their high fire frequency.Yanbian had the highest frequency,and the fires tended to be large with the highest burned area per fire.Yanbian should thus be listed as the key target area by the fire management agency in Jilin Province for better fire prevention.展开更多
Wetlands on the Qinghai-Tibetan Plateau(QTP) perform a dazzling array of vital ecological functions and are one of the most fragile ecosystems in the world. Timely and accurate information describing wetland resources...Wetlands on the Qinghai-Tibetan Plateau(QTP) perform a dazzling array of vital ecological functions and are one of the most fragile ecosystems in the world. Timely and accurate information describing wetland resources and their changes over time is becoming more important in their protection and conservation. By using remote sensing data, this study intended to investigate spatial distribution and temporal variations of wetlands on the QTP at different watershed scales from 1970 s to 2010 s. Results show that wetlands on the QTP have undergone widespread degradation from 1970 s to 2010 s, with nearly 6.4% of their area being lost. Areas of freshwater marsh, salt marsh and wet meadow declined by 46.6%, 53.9% and 15.6%, respectively, while lake area increased by 14.6%. The most extensive losses of natural wetlands have occurred in endorheic basins, such as in the Kunlun-Altun-Qilian Drainage Basin and Qiangtang Basin, which shrank by 44.5% and 33.1%, respectively. A pronounced increase in temperature tends to facilitate the evaporation process and reduce water availability for wetlands. One-third of the wetlands on the QTP are under threat of being submerged due to lakes rising in recent years. More research is needed to gain insight into the interaction mechanisms behind observed variations and potential impacts from further warming in the future.展开更多
The response of diversity and biomass of herbaceous functional groups along an altitudinal gradient in mountainous forests of southern Zagros,Khuzestan Province,Iran was studied by sampling vegetation in 30 circular 1...The response of diversity and biomass of herbaceous functional groups along an altitudinal gradient in mountainous forests of southern Zagros,Khuzestan Province,Iran was studied by sampling vegetation in 30 circular 1000-m^2 plots in herb layer of the forest floor within 646–2447 m asl(lowland:<1000 m asl,midland:1000–2000 m asl,highland:>2000 m asl).The most important herbaceous functional groups were classified based on two aspects of growth form:annuals–perennials,grasses–forbs.Then the relationship between the diversity,richness,evenness,biomass and elevation was analyzed.The results showed that the annual functional group in the low-and midland classes,and perennial functional group in the lowland class had the highest species diversity and evenness in annual and perennial functional groups,respectively(p<0.01).The perennials in the highland class had the maximum total,above-and belowground dry biomass(p<0.01).On the other hand,the forb functional group in the lowland class had the greatest species diversity,richness,and evenness(p<0.01)and in the highland class had the maximum total dry,above-and belowground dry biomass in the grass and forb functional groups(p<0.01).Increasing the diversity,richness,and species evenness resulted in a decrease in the plant dry biomass.展开更多
Background:Forests contribute to human wellbeing through the provision of important ecosystem services.Methods:In this study,we investigated how the perceived importance of ecosystem services may impact the overall be...Background:Forests contribute to human wellbeing through the provision of important ecosystem services.Methods:In this study,we investigated how the perceived importance of ecosystem services may impact the overall benefit provided by managed watersheds at the Hubbard Brook Experimental Forest over a 45-year period,using standardized measures of service capacity weighted by service importance weights derived from a survey of beneficiaries.Results:The capacity of watersheds to regulate water flow and quality was high in all watersheds throughout the study period,whereas cultural services such as scenic beauty declined after harvest.Impacts on greenhouse gas regulation depended on the efficiency with which harvested biomass was used.Surveys revealed that stakeholders placed high value on all ecosystem services,with regulating and cultural services seen as more important than provisioning services.When service metrics were weighted by survey responses and aggregated into a single measure,total service provision followed the same overall trend as greenhouse gas regulation.Where biomass use was less efficient in terms of greenhouse gas emissions,harvesting resulted in an overall "ecosystem service debt";where use was more efficient,this "ecosystem service debt" was reduced.Beneficiaries' educational backgrounds significantly affected overall assessment of service provision.Beneficiaries with college or university degrees incurred smaller "ecosystem service debts" and were less negatively affected by harvesting overall.Conclusions:This study highlights the importance of including empirical measures of beneficiary preference when attempting to quantify overall provision of ecosystem services to human beneficiaries over time.展开更多
This paper highlights the quantitative estimates of plant species diversity and ecosystems of the Rohtang Pass,which is one of the most preferred visiting spots by tourists in Himachal Pradesh (H.P.),India. In spite o...This paper highlights the quantitative estimates of plant species diversity and ecosystems of the Rohtang Pass,which is one of the most preferred visiting spots by tourists in Himachal Pradesh (H.P.),India. In spite of high pressure of anthropogenic activities,the Rohtang Pass still harbours a variety of flowering plants with economic value,including various medicinal herbs. In order to observe species diversity in different landscape elements (LSEs),ground surveys were conducted in nine unique LSEs within the elevation range between 3624 m and 4332 m. Plant community structure in each LSE was studied using stratified random sampling where a total 56 quadrats of 1 m2 in size for herbs and 7 quadrats of 25 m2 for shrubs were made. Of the total 50 plant species belonging to 15 families recorded in different random quadrats,24 species were found of medicinal value. Maximum species richness (18) and value of Shannon diversity (H'=2.2648) were observed on northeast-facing slope in Picrorhiza kurrooa dominated LSE in moist area,followed by Rheum emodi LSE (species richness = 17 and H' = 2.4141) distributed on south-facing slope. Maximum values of species richness and Shannon diversity in Rheum emodi LSE were observed between 8 ～ 12 and 1.4797 ～ 2.1911,respectively. Rhododendron anthopogon dominated LSE on northwest-facing slope was found least diverse in terms of species richness where the Simpson index of dominance (D) was 0.4205. The species were equal in abundance in P. kurrooa LSE on east-facing slope and Pleurospermum candollii LSE on north-facing slope,showing the maximum similarity in terms of species distribution between the two LSEs. Low turnover of species across common LSEs gives an idea regarding their limited distribution. Five species of threatened category according to the IUCN criteria were observed in seven LSEs. The largest population of threatened medicinal plants was recorded on northeast and northwest-facing slopes where population density of Bergenia stracheyi (29.25 individuals/m2),Picrorhiza kurrooa (19.83 individuals/m2) and Rhododendron anthopogon (26.23 individuals/25m2) was highest. Aconitum heterophyllum was recorded for the lowest density (1 individual/m2). It was observed that the distribution of medicinal plants was very habitat-specific. Lower soil pH in most of the LSEs reflected its acidic nature. A significant positive correlation of Shannon diversity was found with soil organic matter,carbon content available and total nitrogen. Considering the continuous pressure of anthropogenic activities,this paper suggests effective ecotourism planning and plant conservation mechanisms to protect valuable plant bioresource at the Rohtang Pass.展开更多
The germination capacity of Ailanthus altissima seeds improved after the seeds were soaked with different concentrations of natural brassinolide (NBR). The germination rate and germination energy of the seeds increase...The germination capacity of Ailanthus altissima seeds improved after the seeds were soaked with different concentrations of natural brassinolide (NBR). The germination rate and germination energy of the seeds increased by 17.6% and 18.8%, and treatment, compared with the control. After hypocotyls ofA. altissima were treated with NBR, the elongation of the hypocotyls inA. altissima hypocotyls.展开更多
基金supported by the financial supports from the Guangdong Basic and Applied Basic Research Foundation(2020A1515010539)the Medical Science and Technology Research Foundation of Guangdong Province,China(A2019046)+1 种基金Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar(50117G25002)the Key Project of Universities in Guangdong Province(2021ZDZX4066).
文摘Aroma(volatile)compounds play important ecological functions in plants,and also contribute to the quality of plant-derived foods.Moreover,chiral aroma compounds affect their functions in plants and lead to different flavor quality properties.Formations of chiral aroma compounds are due to the presence of enzymes producing these compounds in plants,which are generally involved in the final biosynthetic step of the aroma compounds.Here,we review recent progress in research on the plant-derived enzymes producing chiral aroma compounds,and their changes in response to environmental factors.The chiral aroma enzymes that have been reported produce(R)-linalool,(S)-linalool,(R)-limonene,and(S)-limonene,etc.,and these enzymes are found in various plant species.We also discuss the origins of enantioselectivity in the plant-derived enzymes producing chiral aroma compounds and summarize the potential use of plants containing enzymes producing chiral aroma compounds for producing chiral flavors/fragrances.
文摘Climate change is forecast to increase the frequency of extreme hot temperatures and dryer days and is anticipated to have profound impacts on the global carbon budget.Droughts are expected to alter soil respiration(R_(s))rates,but the scarcity of data preclude a reliable estimate of this response and its future trajectory.A field experiment using an automated soil respiration machinery(LI-8100A)was conducted in a natural forest and a plantation during a dry period in the Philippines,with the goal of quantifying Rsrates and their relationship with soil temperature and moisture,and air temperature.The natural forest(5.81μmol m^(-2)s^(-1))exhibited significantly higher Rsrates(p<0.0001)compared with the plantation(1.82μmol m^(-2)s^(-1))and control(3.23μmol m^(-2)s^(-1)).Rsrates showed significant negative relationships with air(-0.71)and soil temperatures(-0.62),indicating that as temperatures increase,the R_(s)rates decrease.In contrast,the R_(s)rates exhibited a significant positive relationship with soil moisture(0.65).Although the low R_(s)rates in the plantation and high Rsrates in the natural forest are indicators of sensitivities of these two types of tropical forests to warm,dry soil,this observation is only conclusive during the dry period,but not necessarily during wet periods.Further studies are needed to determine the trend of Rsrates during wet periods,considering different site conditions and types of vegetation.
基金financially supported by the Urmia University,Iran.
文摘Lake Urmia,Northwest Iran,has confronted a drying procedure in recent years with losing 90%of its water body.The authorities concerned about desertification processes and possible dust events throughout the region.In this regard,the Iranian Natural Resources and Watershed Management Organization has taken ecological measures to plant vegetation using salt cedar(Tamarix ramosissima Ledeb.)shrubs to combat desertification.This study aimed to investigate the vegetation and soil characteristics of natural and plantation stands of salt cedar on the western shores of Lake Urmia.To this end,7 transects were randomly selected with 15 shrubs in natural stands,and 7 transects were randomly selected with 15 shrubs in the plantation parts along the planting rows.Then,vegetative characteristics were examined.Also,soil samples were taken from the vicinity of the shrubs.The results indicated that there was no significant difference between the mean diameter at breast height(DBH)of salt cedar in natural sites.There was a significant difference between the mean number of sprouts per sprout-clumps,mean crown diameter,collar diameter,total height,and also between mean crown diameter and freshness of shrubs among different sites(P<0.05).It was also found that soil variables,such as clay content,organic matter,electrical conductivity(EC),Na^(+),specific absorption rate(SAR),Cl^(-),SO_(4)^(2-),Na^(+),K^(+),and PO_(4)^(2-) are the most significant variable parameters between studied sites.As the results shown,the values of EC,SAR,Na^(+),and Cl^(-)are 6 times higher in the planted stands than in the natural stands of T.ramosissima.Also,the colonization of T.ramosissima in the planted stands is unsuccessful by dramatic drop in the total height and average diameter.Considering the role of soil characteristics in explaining the variance of data and site separation,it seems that these indicators can be applied in executive plans as important indicators to identify suitable planting sites for combating desertification.
基金supported by the National Institute of Forest Science(Project No.FM0800-2019-05)。
文摘Due to considerable deforestation in North Korea,there is a need to plan forest restoration programs based on scientific forest management.In this study,a methodology was developed for estimating the site index values of six major tree species and the forest productivity potential.The site index values of these tree species were derived in South Korea using the Chapman-Richards equation.These values were used with data from the 6th National Forest Inventory,which included 20 types of edaphic,topographic,and climatic factors,and random forest analysis—a widely used machine learning technique for spatial prediction—to develop a new model for estimating the site index values of these species across South Korea.The prediction accuracy of this model was evaluated using the root mean square error.The results show that the prediction accuracy was high,with a root mean square error of~1m.Moreover,the importance of the variables related to climate and geography was generally high.The proposed site index estimation model for six tree species was applied across North Korea,and its effectiveness tested by comparing the estimated values with those reported in literature from North Korea.The differences between the model outputs and recorded data in the northern alpine regions were presumably due to the lack of data for high-altitude regions in South Korea.This model is based on the determination of the suitability of tree species in restoration efforts.Therefore,it can contribute to the evaluation of forest productivity in North Korea and may help plan efficient forest restoration programs.
基金supported by the Jilin Province Science and Technology Department Key Research and Development Project(20200402094N C)。
文摘To evaluate the relationships among clones and open pollinated families from the same plus trees and to select elite breeding materials,growth,and wood characteristics of 33-year-old Pinus korainsis clones and families were measured and analyzed.The results show that growth and wood characters varied significantly.The variation due to clonal effects was higher than that of family effects.The ratio of genetic to phenotypic coefficient of variation of clones in growth and wood traits was above 90%,and the repeatability of these characteristics was more than 0.8,whereas the ratio of genetic to phenotypic coefficient of variation of families was above 90%.The broad-sense heritability of all characteristics exceeded 0.4,and the narrow-sense family heritability of growth traits was less than 0.3.Growth characteristics were positively correlated with each other,but most wood properties were weakly correlated in both clones and families.Fiber length and width were positively correlated between clones and families.Using the membership function method,eleven clones and four families were selected as superior material for improved diameter growth and wood production,and two families from clonal and open-pollinated trees showed consistently better performance.Generally,selection of the best clones is an effective alternative to deployment of families as the repeatability estimates from clonal trees were higher than narrow-sense heritability estimates from open pollinated families.The results provide valuable insight for improving P.koraiensis breeding programs and subsequent genetic improvement.
文摘Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection. However, significant knowledge gaps exist regarding when and where to plant trees. This article reports on a revegetation trial undertaken in St Elizabeth, Mahdia, Guyana, to assess the survival and RGR (Relative Growth Rate) of three native woody trees and shrubs planted within three years old Acacia mangium Willd trees pruned and unpruned blocks. ANOVA (Analysis of Variance) for a completely randomized block design with four blocks, two pruned and two unpruned, within A. mangium plots. Biochar treatment was added to the plants during transplanting. Thirty-six (36) wildlings of Humiria balsamifera (Aublet.) (Tauroniro), Goupia glabra Aublet (Kabukalli), and Vismia guianensis (Aublet.) Choisy (Bloodwood) were collected and raised in a tree nursery for two weeks. The native plants were transplanted 3 m apart, survival observations and each seedling’s initial height and diameter were measured and recorded. After the experiment, 13% of seedlings from a population of 720 had died, with the highest mortality being experienced at the 92 days of the experiment (t ≤ 122 days). While the overall survival rates were high, emphasizing the importance of field trials on native and exotic species in different environments is essential to fill the knowledge gaps on suitable species for restoration in degraded areas with other land use histories.
基金supported by the National Natural Science Foundation of China (41071152)the Special Fund for Land and Resources Scientific Research in the Public Interest,China (201011006-3)the Special Fund for Agro-Scientific Research in the Public Interest,China (201103005-01-01)
文摘The spatial interpolation for soil texture does not necessarily satisfy the constant sum and nonnegativity constraints. Meanwhile, although numeric and categorical variables have been used as auxiliary variables to improve prediction accuracy of soil attributes such as soil organic matter, they (especially the categorical variables) are rarely used in spatial prediction of soil texture. The objective of our study was to comparing the performance of the methods for spatial prediction of soil texture with consideration of the characteristics of compositional data and auxiliary variables. These methods include the ordinary kriging with the symmetry logratio transform, regression kriging with the symmetry logratio transform, and compositional kriging (CK) approaches. The root mean squared error (RMSE), the relative improvement value of RMSE and Aitchison's distance (D_A) were all utilized to assess the accuracy of prediction and the mean squared deviation ratio was used to evaluate the goodness of fit of the theoretical estimate of error. The results showed that the prediction methods utilized in this paper could enable interpolation results of soil texture to satisfy the constant sum and nonnegativity constraints. Prediction accuracy and model fitting effect of the CK approach were better, suggesting that the CK method was more appropriate for predicting soil texture. The CK method is directly interpolated on soil texture, which ensures that it is optimal unbiased estimator. If the environment variables are appropriately selected as auxiliary variables, spatial variability of soil texture can be predicted reasonably and accordingly the predicted results will be satisfied.
基金supported by the NationalNatural Science Foundation of China (30771484)Guangdong Agricultural Science and Technology De-velopment Foundation, China (2007A020200006)the Natural Science Foundation of Guangdong Province,China (2007-73)
文摘Jackfruit is cross-pollinated and mostly seed propagated, a wide range of variation exists in fruit quality. With the development of efficient vegetative propagation methods, excellent genotypes selected from these seed propagated seedlings will gradually replace other genotypes in jackfruit producing areas. In this study, genetic diversity of 50 jackfruit accessions from three provinces in China was analyzed based on amplified fragment length polymorphic (AFLP) markers. A total of 320 unambiguous bands were produced by eight primer combinations, and 65 (20.3%) of them were polymorphic. Genetic similarity coefficients ranged from 0 to 0.9841, with an average of 0.5000, indicating a moderate genetic diversity in this collection. The dendrogram derived by unweighted pair group method with arithmetic mean algorithm (UPGMA) analysis revealed five groups, and no correlation between genetic relationship and geographical origin were found. Accessions of soft and firm flesh type were not clustered into distinct groups, neither could yearly bearing once, or twice fruit accessions. This study has provided useful information for collection and preservation of jackfruit germplasm worldwide.
基金financially supported by the International Science and Technology Cooperation Program of China (2012DFR30830)the National Natural Science Foundation of China (41261047)+1 种基金the Gansu Science and Technology Support Program(1204NKCA084)the Project of Knowledge Innovation of the Chinese Academy of Sciences(KZCX3-SW-342)
文摘Water deficit in arid and semiarid regions affects whole-plant sap flow and leaf-level water relations. The objectives of this study were to clarify how sap flow of Calligonum arborescens responds to different drought stress conditions and to understand its acclimation mechanism to drought environments. A field experiment was conducted for C. arborescens during the growing season to evaluate the effects of deficit irrigation on the daily and seasonal variations of trunk sap flow in the shelterbelt along the Tarim Desert Highway, Xinjiang, China. Three different water regimes (2,380, 1,960 and 1,225 m3 /hm2 ) were applied at different stages of plant growth. From 1 May to 30 October 2007, a heat-balance stem flow gauge was used to monitor the sap flow dynamics of C. arborescens under different water regimes. Atmospheric evaporation demand and soil moisture conditions for differentially irrigated C. arborescens were also monitored. The result showed that sap flow exhibited a clear diurnal pattern regardless of treatments; the diurnal patterns of sap flow and vapour pressure deficit were very similar under different water regimes and growing seasons, while the slope of the linear regression of this correlation confirmed an increasing water regime. The sap flow decreased under reduced water regimes and there was nocturnal sap flow regardless of water regimes, which was mainly contributed to nocturnal transpiration and water recharge. The sap flow peaked before midnight and dropped afterwards with obviously higher values in summer than in other seasons. It is speculated that the water consumption of C. arborescens during the day can be supplemented through the sap flow at night, which increased with increasing irrigation amount. Net radiation was the most significant correlated factor that influenced sap flow velocity and transpiration under different water regimes (R2 >0.719). Compared with the commonly practiced water regime, the growth of C. arborescens was significantly slower in the stress deficit irrigation, but not significantly different from that in the moderate deficit irrigation. The moderate deficit irrigation would not affect the stability of the shelterbelt and was a more efficient use of water resources compared with the current watering amount.
基金financially supported by the National Science and Technology Program of China during the Twelfth FiveYear Plan Period(Grant No.2013AA102704)the Fundamental Research Funds for the Central Universities(Grant No.2572015EA03)
文摘The growth traits(tree height, diameter at breast height, and stem straightness degree) and wood properties[wood density(WD), fiber length, fiber width, ash content(AC), lignin content, cellulose content, hemicellulose content(HEC), and holocellulose content] of 208 26-yearold Larix olgensis clones were analyzed. Except for WD and AC, there were significant differences(p \ 0.01) for all traits among clones. The phenotypic coefficient of variation and repeatability of all traits were 9.34–35.33%and 0.218–0.930, respectively. Tree height and diameter at breast height showed significant positive correlation;however, the correlation coefficients among growth characteristics and wood properties were mostly not significant.Ten clones(L70, L56, L82, L90, L59, L91, L61, L92, L86,and L64) were selected as excellent clones under a selection rate of 5%, using tree height, diameter at breast height,and stem straightness degree as evaluation indexes, providing genetic gains of 28.69, 17.96, and 0.67%, respectively. Ten clones(L88, L305, L59, L66, L253, L304,L277, L298, L248, and L293) were selected as excellent clones using wood properties as an evaluation index, with a selection rate of 5%, providing genetic gains in WD, fiber length, fiber width, cellulose content, and HEC of 4.14,3.64, 9.28, 6.77, and 9.61%, respectively. This study provides a theoretical basis for selecting excellent L. olgensis clones.
基金supported by grants Seedling Technology Rules of Siberia pine(No.2012-LY-183)
文摘Siberian Pine(Pinus sibirica) is an ecologically and economically important species in pristine forests throughout northern Russia. Four provenances of P. sibirica were introduced from Mongolia and Russia to the Greater Xing'an Range(the Daxing'anling), northeast China in 1993. The aim of this research was to study genetic variation and selection of the introduced four Pinus sibirica provenances. Heights(H), basal diameters(BD), survival rates(SR) and crown lengths(CL) of different families were measured as primary outcomes in different growth years. Results of data analyses demonstrated high coefficients of phenotypic variation(PCV) and heritability(H2) for H, BD and CL at 18 years after introduction. PCV and H2 increased with age. Correlations of growth traits between any two growth years were all significantly positive, but the correlation coefficient was smaller when the growth year interval was larger. Correlations between H and the original environment factors decreased gradually, indicating that with long-term subsistence in the new environment, the influence of the source environment declined. Colligation of multiple traits to estimate provenances showed that Novosibirsk, Tomsk, and Altai Mountains had higher survival rates and biomass, and proved more suitable for introduction and plantation in the Greater Xing'an Range in China.
基金supported by the Innovation Project of State Key Laboratory of Tree Genetics and Breeding(Northeast Forestry University)(No.2016C02)China Postdoctoral Science Foundation(2014M561315)
文摘Early selection is an important method to shorten the breeding cycle for tree species, which may differ in the time for early selection.To evaluate the early selected time for Larix kaempferi, tree height and diameter at breast height of 57 L.kaempferi clones were measured over many different growth years.The results indicated that, except for age × clone interaction for diameter at breast height(P = 0.741), there were significant differences among all variation sources(P < 0.01).The coefficient of phenotypic variation ranged from 14.89 to 35.65%for height and from 19.17 to 23.86% for diameter at breast height in different growth years.The repeatability of height and of diameter at breast height among clones was high,ranging from 0.6181 to 0.8531(height) and from 0.8443 to0.8497(diameter at breast height), in different growth years.There were significant positive correlations between all pairs of growth traits except between height in the 2 nd growth year and height in the 30 th growth year; and between height in the 2 nd growth year × diameter at breast height in the 30 th growth year.With a comprehensive evaluation method and a selection ratio of 10%, L65,L1, L62, L9, L15, and L78 were selected as excellent clones in the 30 th growth year.Their average values of height and diameter at breast height were 9.81 and 16.57%higher than the overall average, representing genetic gains of 6.46 and 13.99%, respectively.This study provides a theoretical foundation for the genetic improvement of L.kaempferi.
基金This research was supported by Ph.D. Startup Funding and Overseas Scholar Funding from Institute of Applied Ecology, Chinese Academy of Sciences and funding from Opened Research Station of Changbai Mountain Forest Ecosystems.
基金financially supported by the National Natural Science Foundation of China(31470497)Project 2013-158,Jilin Provincial Education Department+1 种基金Project 2013-007,Jilin Provincial Forestry Departmentsupported by the Program for New Century Excellent Talents in the University(NCET-12-0726)
文摘We evaluated the spatial and temporal patterns of forest fires in two fire seasons(March to June and September to November) from 1996 to 2010 in Jilin Province,China,using the Canadian Forest Fire Weather Index System.Fire data were obtained from the Provincial Fire Agency,and historical climate records of daily weather observations were collected from 36 weather stations in Jilin and its neighboring provinces.A linear regression model was used to analyze linear trends between climate and fire weather indices with time treated as an independent variable.Correlation analysis was used to detect correlations between fire frequency,areas burned,and fire weather indices.A thin-plate smooth spline model was used to interpolate the point data of 36 weather stations to generate a surface covering the whole province.Our analyses indicated fire frequency and areas burned were significantly correlated with fire weather indices.Overall,the Canadian Forest Fire Weather Index System appeared to be work well for determining the fire danger rating in Jilin Province.Also,our analyses indicated that in the forthcoming decades,the overall fire danger in March and April should decrease across the province,but the chance of a large fire in these months would increase.The fire danger in the fall fire season would increase in the future,and the chance of large fire would also increase.Historically,because most fires have occurred in the spring in Jilin Province,such a shift in the future fire danger between the two fire seasons would be beneficial for the province's fire management.
基金financially supported by the National Key Research and Development Plan(2017YFD0600106)the National Natural Science Foundation of China under Grant31470497+1 种基金Project 2013-007,Jilin Provincial Forestry Departmentsupported by the Program for New Century Excellent Talents in University(NCET-12-0726)
文摘Forest fires caused by natural forces or human activities are one of the major natural risks in Northeast China.The incidence and spatial distribution of these fires vary over time and across the forested areas in Jilin Province,Northeast China.In this study,the incidence and distribution of 6519 forest fires from 1969 to 2013 in the province were investigated.The results indicated that the spatiotemporal distribution of the burnt forest area and the fire frequency varied significantly by month,year,and region.Fire occurrence displayed notable temporal patterns in the years after forest fire prevention measures were strictly implemented by the provincial government.Generally,forest fires in Jilin occurred in months when stubble and straw were burned and human activities were intense during traditional Chinese festivals.Baishan city,Jilin city,and Yanbian were defined as fire-prone regions for their high fire frequency.Yanbian had the highest frequency,and the fires tended to be large with the highest burned area per fire.Yanbian should thus be listed as the key target area by the fire management agency in Jilin Province for better fire prevention.
基金Under the auspices of the National Key Research and Development Program of China(No.2016YFC050040106,2016YFA060230302)the National Science Foundation of China(No.41671087,41671081,41471081)the Technological Basic Research Program of China(No.2013FY111800)
文摘Wetlands on the Qinghai-Tibetan Plateau(QTP) perform a dazzling array of vital ecological functions and are one of the most fragile ecosystems in the world. Timely and accurate information describing wetland resources and their changes over time is becoming more important in their protection and conservation. By using remote sensing data, this study intended to investigate spatial distribution and temporal variations of wetlands on the QTP at different watershed scales from 1970 s to 2010 s. Results show that wetlands on the QTP have undergone widespread degradation from 1970 s to 2010 s, with nearly 6.4% of their area being lost. Areas of freshwater marsh, salt marsh and wet meadow declined by 46.6%, 53.9% and 15.6%, respectively, while lake area increased by 14.6%. The most extensive losses of natural wetlands have occurred in endorheic basins, such as in the Kunlun-Altun-Qilian Drainage Basin and Qiangtang Basin, which shrank by 44.5% and 33.1%, respectively. A pronounced increase in temperature tends to facilitate the evaporation process and reduce water availability for wetlands. One-third of the wetlands on the QTP are under threat of being submerged due to lakes rising in recent years. More research is needed to gain insight into the interaction mechanisms behind observed variations and potential impacts from further warming in the future.
基金funding of project is supported by Lorestan University,Iran。
文摘The response of diversity and biomass of herbaceous functional groups along an altitudinal gradient in mountainous forests of southern Zagros,Khuzestan Province,Iran was studied by sampling vegetation in 30 circular 1000-m^2 plots in herb layer of the forest floor within 646–2447 m asl(lowland:<1000 m asl,midland:1000–2000 m asl,highland:>2000 m asl).The most important herbaceous functional groups were classified based on two aspects of growth form:annuals–perennials,grasses–forbs.Then the relationship between the diversity,richness,evenness,biomass and elevation was analyzed.The results showed that the annual functional group in the low-and midland classes,and perennial functional group in the lowland class had the highest species diversity and evenness in annual and perennial functional groups,respectively(p<0.01).The perennials in the highland class had the maximum total,above-and belowground dry biomass(p<0.01).On the other hand,the forb functional group in the lowland class had the greatest species diversity,richness,and evenness(p<0.01)and in the highland class had the maximum total dry,above-and belowground dry biomass in the grass and forb functional groups(p<0.01).Increasing the diversity,richness,and species evenness resulted in a decrease in the plant dry biomass.
基金support from the USDA Forest Service's Northeastern States Research Cooperative(NSRC)in collaboration with the Hubbard Brook Research Foundationthe Cary Institute of Ecosystem Studies
文摘Background:Forests contribute to human wellbeing through the provision of important ecosystem services.Methods:In this study,we investigated how the perceived importance of ecosystem services may impact the overall benefit provided by managed watersheds at the Hubbard Brook Experimental Forest over a 45-year period,using standardized measures of service capacity weighted by service importance weights derived from a survey of beneficiaries.Results:The capacity of watersheds to regulate water flow and quality was high in all watersheds throughout the study period,whereas cultural services such as scenic beauty declined after harvest.Impacts on greenhouse gas regulation depended on the efficiency with which harvested biomass was used.Surveys revealed that stakeholders placed high value on all ecosystem services,with regulating and cultural services seen as more important than provisioning services.When service metrics were weighted by survey responses and aggregated into a single measure,total service provision followed the same overall trend as greenhouse gas regulation.Where biomass use was less efficient in terms of greenhouse gas emissions,harvesting resulted in an overall "ecosystem service debt";where use was more efficient,this "ecosystem service debt" was reduced.Beneficiaries' educational backgrounds significantly affected overall assessment of service provision.Beneficiaries with college or university degrees incurred smaller "ecosystem service debts" and were less negatively affected by harvesting overall.Conclusions:This study highlights the importance of including empirical measures of beneficiary preference when attempting to quantify overall provision of ecosystem services to human beneficiaries over time.
文摘This paper highlights the quantitative estimates of plant species diversity and ecosystems of the Rohtang Pass,which is one of the most preferred visiting spots by tourists in Himachal Pradesh (H.P.),India. In spite of high pressure of anthropogenic activities,the Rohtang Pass still harbours a variety of flowering plants with economic value,including various medicinal herbs. In order to observe species diversity in different landscape elements (LSEs),ground surveys were conducted in nine unique LSEs within the elevation range between 3624 m and 4332 m. Plant community structure in each LSE was studied using stratified random sampling where a total 56 quadrats of 1 m2 in size for herbs and 7 quadrats of 25 m2 for shrubs were made. Of the total 50 plant species belonging to 15 families recorded in different random quadrats,24 species were found of medicinal value. Maximum species richness (18) and value of Shannon diversity (H'=2.2648) were observed on northeast-facing slope in Picrorhiza kurrooa dominated LSE in moist area,followed by Rheum emodi LSE (species richness = 17 and H' = 2.4141) distributed on south-facing slope. Maximum values of species richness and Shannon diversity in Rheum emodi LSE were observed between 8 ～ 12 and 1.4797 ～ 2.1911,respectively. Rhododendron anthopogon dominated LSE on northwest-facing slope was found least diverse in terms of species richness where the Simpson index of dominance (D) was 0.4205. The species were equal in abundance in P. kurrooa LSE on east-facing slope and Pleurospermum candollii LSE on north-facing slope,showing the maximum similarity in terms of species distribution between the two LSEs. Low turnover of species across common LSEs gives an idea regarding their limited distribution. Five species of threatened category according to the IUCN criteria were observed in seven LSEs. The largest population of threatened medicinal plants was recorded on northeast and northwest-facing slopes where population density of Bergenia stracheyi (29.25 individuals/m2),Picrorhiza kurrooa (19.83 individuals/m2) and Rhododendron anthopogon (26.23 individuals/25m2) was highest. Aconitum heterophyllum was recorded for the lowest density (1 individual/m2). It was observed that the distribution of medicinal plants was very habitat-specific. Lower soil pH in most of the LSEs reflected its acidic nature. A significant positive correlation of Shannon diversity was found with soil organic matter,carbon content available and total nitrogen. Considering the continuous pressure of anthropogenic activities,this paper suggests effective ecotourism planning and plant conservation mechanisms to protect valuable plant bioresource at the Rohtang Pass.
文摘The germination capacity of Ailanthus altissima seeds improved after the seeds were soaked with different concentrations of natural brassinolide (NBR). The germination rate and germination energy of the seeds increased by 17.6% and 18.8%, and treatment, compared with the control. After hypocotyls ofA. altissima were treated with NBR, the elongation of the hypocotyls inA. altissima hypocotyls.
