The effects of different basic seedlings, N application rates and paclobutrazol measures on the development and yield of Tongyoujing 1 population were studied through the D-saturated optimum regression design tests. T...The effects of different basic seedlings, N application rates and paclobutrazol measures on the development and yield of Tongyoujing 1 population were studied through the D-saturated optimum regression design tests. The results showed thatthe effects of various factors on yield under the experimental conditions were in order of N application rate basic seedlings paclobutrazol dosage. The increases of basic seedlings and N application rate are beneficial to the increases of population quantity and tiller density, and could improve number of panicles per unit area and increase the population leaf area and accumulated amount of dry matter.However, too-high basic seedlings and N application rate would reduce reproductive tiller percentage and economic coefficient, and prolong growth duration. Proper basic seedlings could coordinate the correlation between tiller density and productive tiller percentage, ensure higher leaf area and dry matter accumulation at filling stage,and improve yield of Tongyoujing 1. According to the multivariate nonlinear regression analysis of yield with various factors, Tongyoujing 1 could reach its maximum yield potential of 12 606.0 kg/hm2 under the basic seedlings of 55.2×104/hm2, N application rate at 339.2 kg/hm2, and paclobutrazol dosage of 97.9 g/hm2. The comprehensive agricultural measures for a yield higher than 11 250 kg/hm2were： basic seedlings 52.6 ×10^4-60.1 ×10^4/hm2, N application rate 328.0-356.1 kg/hm2, and paclobutrazol dosage 87.6-104.6 g/hm2.展开更多
The growth period, population tiller dynamics, plant characters, paniclegrain structure, yielding ability and stress resistance of a wheat variety Heibaoshi 1 were studied using a two-factor split plot design to inves...The growth period, population tiller dynamics, plant characters, paniclegrain structure, yielding ability and stress resistance of a wheat variety Heibaoshi 1 were studied using a two-factor split plot design to investigate the effects of different density and fertilizer levels on individual development and yield of Heibaoshi 1 in riparian region of Jiangsu Province. In addition, high-yielding agronomic measures were explored through multiple non-linear regression analysis. The results showed that low density was not conducive to the formation of panicles, while high density affected grain number per panicle; low fertilizer level restricted individual development, while high fertilizer level affected grain number per panicle and grain weight and was prone to leading to lodging. Reasonable combination of density and fertilizer could coordinate individual development and balance panicle, grain and weight, thus achieving a high yield. The yield potential was highest （7 384.3 kg/hm2） under density of 239.6×104 basic seedlings/hm2 and N level of 237.7 kg/hm2. When the planting density ranged from 200×104 to 270×104 basic seedlings/hm2 and the N level ranged from 220 to 260 kg/hm2 or the density basic seedling number ranged from 210×104/hm2 to 260×104/hm2 and the N level ranged from 210 to 270 kg/hm2, the yield could exceed 7 200 kg/hm2.展开更多
Lymphocystis disease,caused by the lymphocystis disease virus (LCDV),is a significant worldwide problem in fish industry causing substantial economic losses.In this study,we aimed to develop the DNA vaccine against LC...Lymphocystis disease,caused by the lymphocystis disease virus (LCDV),is a significant worldwide problem in fish industry causing substantial economic losses.In this study,we aimed to develop the DNA vaccine against LCDV,using DNA vaccination technology.We evaluated plasmid pEGFP-N2-LCDV1.3 kb as a DNA vaccine candidate.The plasmid DNA was transiently expressed after liposome transfection into the eukaryotic COS 7 cell line.The distribution and expression of the DNA vaccine (pEGFP-N2-LCDV1.3kb) were also analyzed in tissues of the vaccinated Japanese flounder by PCR,RT-PCR and fluorescent microscopy.Results from PCR analysis indicated that the vaccine-containing plasmids were distributed in injected muscle,the muscle opposite the injection site,the hind intestine,gill,spleen,head,kidney and liver,6 and 25 days after vaccination.The vaccine plasmids disappeared 100 d post-vaccination.Fluorescent microscopy revealed green fluorescence in the injected muscle,the muscle opposite the injection site,the hind intestine,gill,spleen,head,kidney and liver of fish 48 h post-vaccination,green fluorescence did not appear in the control treated tissue.Green fluorescence became weak at 60 days post-vaccination.RT-PCR analysis indicated that the mcp gene was expressed in all tested tissues of vaccinated fish 6-50 days post-vaccination.These results demonstrate that the antigen encoded by the DNA vaccine is distributed and expressed in all of the tissues analyzed in the vaccinated fish.The antigen would therefore potentially initiate a specific immune response.The plasmid DNA was injected into Japanese flounder (Paralichthys olivaceus) intramuscularly and antibodies against LCDV were evaluated.The results indicate that the plasmid encoded DNA vaccine could induce an immune response to LCDV and would therefore offer immune protection against LCD.Further studies are required for the development and application of this promising DNA vaccine.展开更多
The yield and yield components of Japonica variety Tongjing 981 under different density and fertilization levels were studied through regression and correlation and path analysis. The results showed that the number of...The yield and yield components of Japonica variety Tongjing 981 under different density and fertilization levels were studied through regression and correlation and path analysis. The results showed that the number of panicles per unit area, number of filled grains per panicle and 1 000-grain weight all had very significant yield increasing effects, and the number of panicles per unit area played a leading role. However, the yield increasing effects of the number of panicles per unit area and number of filled grains per panicle are equally important when the basic seedlings are more or the N fertilizer application rate is large. In practical production, a major factor should be determined among the yield components, and rational cultivation measures should be taken accordingly, to improve yield.展开更多
Many researches showed a comprehensive assessment of the cropping practice effect on greenhouse gas （GHG） emissions per unit yield （yield-scaled） rather than per the land area （area-scaled）, and it was noteworth...Many researches showed a comprehensive assessment of the cropping practice effect on greenhouse gas （GHG） emissions per unit yield （yield-scaled） rather than per the land area （area-scaled）, and it was noteworthy that cropping practices decided to increase or decrease grain yield, and reduce or promote greenhouse gas emissions. In this study, a meta-analysis was conducted to quantify the effects of rice basic seedlings （BS） on the global warming potential （GWP） of GHG emissions at the yield-scale in China. The results suggested that significant difference was observed in yield-scaled GWP of BS. The lowest yield-scaled GWP occurred at 80-100 BS （415.65 kg CO2 equiv/mg）. The yield-scaled GHG emission from high to low was that of the hybrid rice varieties （1 028.86 kg CO2 equiv/mg）, the conventional rice varieties （634.15 kg CO2 equiv/mg） and the super rice varieties （576.57 kg CO2 equiv/mg）. Consequently, the model of conventional rice varieties and super rice varieties at 80-100 BS could be a scientifc method of matching inthe rice cropping system. A further assessment of rice density and variety impacts on GHG emissions at yield-scale was urgently needed to develop, so as to achieve win-win policies of rice production for higher yield with lower emissions.展开更多
To detect retrospectively the phenotype and stability of the E-protein gene in Japanese Encephalitis （JE） virus strain SA14-14-2 used in the live-attenuated JE vaccine prepears, the viral titer was titrated by plaqu...To detect retrospectively the phenotype and stability of the E-protein gene in Japanese Encephalitis （JE） virus strain SA14-14-2 used in the live-attenuated JE vaccine prepears, the viral titer was titrated by plaque formation in BHK-21 cell cultures, and the neuro-virulence of viruses was assayed in mice with body weight of 12-14 g by intracerebral inoculation. Meanwhile, the total RNA of virus gene was extracted and amplified by RT-PCR with the designed primers, and then it was purified and cloned to the expression vector pGEM-T. The recombinant plasmid was purified and sequenced. It was found that the loss of viral titer of vaccines stored in -20℃ for longer than 10 years was less than 0.5 Lg PFU/ml. No mice inoculated intracerebrally showed signs of illness or even death. The size of plagues of the vaccine virus remained to be small, and the E genes of primary virus seed SA14-14-2 and the vaccines prepared at different years （1987-2001） were unchanged, in- cluding the 8 critical amino acid sites which were different from the parent wild virus strain SA14 and the related neuro-virulence. These results indicate that the genotypic and biological characteristics of the attenuated JE virus strain SA14-14-2 and its vaccines sion noted. prepared are quite stable without any reversion noted.展开更多
The purpose of this study was to understand the stability and possibility of back mutation of Japanese encephalitis （JE） attenuated vaccine virus strain SA14-14-2 HKs on molecular level. The E genes of the SA14-14-2...The purpose of this study was to understand the stability and possibility of back mutation of Japanese encephalitis （JE） attenuated vaccine virus strain SA14-14-2 HKs on molecular level. The E genes of the SA14-14-2 HKs vaccine virus and its PHK cells passaged virus （SA14-14-2 HK17 ）, its mouse brain passaged virus （SA14-14-2 SM1 ） were sequenced and compared with the E gene of parental SAI4 virus. The total RNA was extracted from infected Vero cells and amplified by RT-PCR. The RT-PCR products were purified and cloned into T-vector. Positive clones were screened, identified and sequenced. There were twelve nucleotides and eight amino acids substitutions between SA14 parent virus and SA14-34-2 PHKs vaccine virus. The SA14-14-2 PHK17 virus showed two additional mutations （E-331 and E-398） which were not back mutations. Although five additional mutations were found in SA14-34-2 SMt virus, only one （E-307） was back mutation. Genetic characteristics of the attenuated vaccine virus SA14- 34-2 were stable when it was passaged 37 times on PHK cells or one time in mouse brains.展开更多
The study was aimed at evaluating growth response of Heteroclarias fingerlings fed diet in which fish meal was substituted with graded levels of earthworm meal. The replacement levels were 0.00%, 25%, 50%, 75% and 100...The study was aimed at evaluating growth response of Heteroclarias fingerlings fed diet in which fish meal was substituted with graded levels of earthworm meal. The replacement levels were 0.00%, 25%, 50%, 75% and 100% designated as Eo, E25, Es0, E75 and El00, respectively. Fingerlings used for the work were obtained through artificial insemination of brood stock （purchased from local farmers） with ovaprim in the laboratory. The resulting fry were reared and fed with cultured plankton for 2 weeks followed by 100% fish meal for another two weeks. Thereafter sixteen fingerlings weighing 4.73 g and measuring 6.512 mm standard length （on the average） were starved over night and reared in five indoors tanks （0.8 ~ 0.5 ~ 0.5 m） in duplicate for eight weeks. Fingerlings were fed on graded earthworm meals of 40% protein twice daily at 08：00 and 16：00. The highest mean weight （6.77 g）, specific growth rate （0.86） and protein efficiency ratio （0.6） were obtained at 50% replacement level. Also, Food conversion ratio was the highest at 50% substitution level and lowest at 0.00% substitution, indicating that fingerlings use earthworm containing meal more efficiently. Furthermore, cost benefit analysis revealed that the profit index for 50% inclusion of earthworm meal was the highest （1.71） and the highest net profit of N374.32 （circa $2.3） was achieved at this level. Water quality parameters observed were within tolerable values for the fingerlings well being. Consequently, farmers are advised to use 50% earthworm meal in place of fish meal for formulation of Heteroclarias fingerlings diet. This will drastically reduce production cost, increase farmers profit and enhance the biological value of our menu.展开更多
Almost three-fourths of forests are experiencing anthropogenic disturbances globally, and more than two-thirds of the forests in Nepal receive different types of disturbances. In community forests(CFs), local communit...Almost three-fourths of forests are experiencing anthropogenic disturbances globally, and more than two-thirds of the forests in Nepal receive different types of disturbances. In community forests(CFs), local communities are dependent on the ecosystem services provided by the forests for various aspects of their livelihoods, which disturb the forests’ natural conditions and ecosystem functioning in a variety of ways. This study tested the major disturbance factors that had influential roles on plant species diversity, recruitment(seedlings and saplings), biomass, soil organic carbon(SOC) and total carbon density in two community-managed forests in the Mid-hills of Nepal. The stump number, cut-off seedlings and saplings, lopping, dropping, and grazing/trampling were used as measures of the major anthropogenic disturbances. The necessary data were collected from 89 randomly selected sample plots, each with an area of 250 m2. The responses to anthropogenic disturbances were analyzed using Generalized Linear Models(GLM). The results showed that forest lopping was the most significant anthropogenic disturbance for biomass and total carbon density balance. A higher degree of lopping in the forests resulted in a lowering of the forests’ carbon stock in the study area. SOC showed no significant response to any of the tested anthropogenic disturbances. Woody species richness and number of saplings increased with an increasing number of stumps, which signifies that intermediate disturbance was beneficial. However, a higher intensity of lopping reduced the sapling density. Grazing/trampling was the most significant disturbance for inhibiting seedling growth. Areas in the forests with a higher intensity of trampling showed lower numbers of seedlings and saplings. These results will be a guide for managing anthropogenic disturbances in multiple-use forests in Nepal, as well as those in similar socio-economic environments worldwide.展开更多
Pinus tabulaeformis seedlings were grown under a factorial design to measure biomass accumulation and P, Na and K concentrations of plants, with 3 different ectomycorrhizal fungus (EMF) strains (Boletus edulis, Xeroco...Pinus tabulaeformis seedlings were grown under a factorial design to measure biomass accumulation and P, Na and K concentrations of plants, with 3 different ectomycorrhizal fungus (EMF) strains (Boletus edulis, Xerocomus chrysenteron and Gomphidius viscidus) and two P treatments (with or without extra P). Growth and mineral nutrition of pine seedlings were stimulated by three EMF under salinity stress. Na concentrations were changed and plant K and P concentrations were increased significantly by EMF. Adding extra P made no difference in accumulation of seedlings biomass, and did not assist element absorption of plants. Although three strains of EMF can all enhance the tolerance of pine seedlings to salinity stress, they may utilize different mechanisms because of different performance in absorption of elements. The increased P and K accumulation and the balance of ion concentrations might be due to the enhanced tolerance of EMF-inoculated plants to saline conditions.展开更多
The use of cholera vaccines has been increasingly recognized as an effective control measure in cholera endemic countries. However, guidelines for using vaccination during cholera outbreaks are still to be established...The use of cholera vaccines has been increasingly recognized as an effective control measure in cholera endemic countries. However, guidelines for using vaccination during cholera outbreaks are still to be established, and it remains an open question as to how and when the vaccines should be deployed to best control ongoing cholera outbreaks. Here we formulate a new optimal control model to assess the value of cholera vaccines in epidemic settings and cost-effective optimal times to deploy a vaccine. Our results suggest that as long as the vaccine prices are sufficiently low, vaccination should always start from or immediately after the onset of a cholera outbreak.展开更多
基金Supported by Jiangsu Sanxin Agricultural Innovation Project(SXGC[2014]188)~~
文摘The effects of different basic seedlings, N application rates and paclobutrazol measures on the development and yield of Tongyoujing 1 population were studied through the D-saturated optimum regression design tests. The results showed thatthe effects of various factors on yield under the experimental conditions were in order of N application rate basic seedlings paclobutrazol dosage. The increases of basic seedlings and N application rate are beneficial to the increases of population quantity and tiller density, and could improve number of panicles per unit area and increase the population leaf area and accumulated amount of dry matter.However, too-high basic seedlings and N application rate would reduce reproductive tiller percentage and economic coefficient, and prolong growth duration. Proper basic seedlings could coordinate the correlation between tiller density and productive tiller percentage, ensure higher leaf area and dry matter accumulation at filling stage,and improve yield of Tongyoujing 1. According to the multivariate nonlinear regression analysis of yield with various factors, Tongyoujing 1 could reach its maximum yield potential of 12 606.0 kg/hm2 under the basic seedlings of 55.2×104/hm2, N application rate at 339.2 kg/hm2, and paclobutrazol dosage of 97.9 g/hm2. The comprehensive agricultural measures for a yield higher than 11 250 kg/hm2were： basic seedlings 52.6 ×10^4-60.1 ×10^4/hm2, N application rate 328.0-356.1 kg/hm2, and paclobutrazol dosage 87.6-104.6 g/hm2.
文摘The growth period, population tiller dynamics, plant characters, paniclegrain structure, yielding ability and stress resistance of a wheat variety Heibaoshi 1 were studied using a two-factor split plot design to investigate the effects of different density and fertilizer levels on individual development and yield of Heibaoshi 1 in riparian region of Jiangsu Province. In addition, high-yielding agronomic measures were explored through multiple non-linear regression analysis. The results showed that low density was not conducive to the formation of panicles, while high density affected grain number per panicle; low fertilizer level restricted individual development, while high fertilizer level affected grain number per panicle and grain weight and was prone to leading to lodging. Reasonable combination of density and fertilizer could coordinate individual development and balance panicle, grain and weight, thus achieving a high yield. The yield potential was highest （7 384.3 kg/hm2） under density of 239.6×104 basic seedlings/hm2 and N level of 237.7 kg/hm2. When the planting density ranged from 200×104 to 270×104 basic seedlings/hm2 and the N level ranged from 220 to 260 kg/hm2 or the density basic seedling number ranged from 210×104/hm2 to 260×104/hm2 and the N level ranged from 210 to 270 kg/hm2, the yield could exceed 7 200 kg/hm2.
基金Supported by the National High Technology Research and Development Program of China (863 Program) (No. [0]2006AA100309)
文摘Lymphocystis disease,caused by the lymphocystis disease virus (LCDV),is a significant worldwide problem in fish industry causing substantial economic losses.In this study,we aimed to develop the DNA vaccine against LCDV,using DNA vaccination technology.We evaluated plasmid pEGFP-N2-LCDV1.3 kb as a DNA vaccine candidate.The plasmid DNA was transiently expressed after liposome transfection into the eukaryotic COS 7 cell line.The distribution and expression of the DNA vaccine (pEGFP-N2-LCDV1.3kb) were also analyzed in tissues of the vaccinated Japanese flounder by PCR,RT-PCR and fluorescent microscopy.Results from PCR analysis indicated that the vaccine-containing plasmids were distributed in injected muscle,the muscle opposite the injection site,the hind intestine,gill,spleen,head,kidney and liver,6 and 25 days after vaccination.The vaccine plasmids disappeared 100 d post-vaccination.Fluorescent microscopy revealed green fluorescence in the injected muscle,the muscle opposite the injection site,the hind intestine,gill,spleen,head,kidney and liver of fish 48 h post-vaccination,green fluorescence did not appear in the control treated tissue.Green fluorescence became weak at 60 days post-vaccination.RT-PCR analysis indicated that the mcp gene was expressed in all tested tissues of vaccinated fish 6-50 days post-vaccination.These results demonstrate that the antigen encoded by the DNA vaccine is distributed and expressed in all of the tissues analyzed in the vaccinated fish.The antigen would therefore potentially initiate a specific immune response.The plasmid DNA was injected into Japanese flounder (Paralichthys olivaceus) intramuscularly and antibodies against LCDV were evaluated.The results indicate that the plasmid encoded DNA vaccine could induce an immune response to LCDV and would therefore offer immune protection against LCD.Further studies are required for the development and application of this promising DNA vaccine.
基金Supported by National Spark Program(2013GA690123)Agricultural New Variety Postsubsidy Project of Major Research and Development Programof Jiangsu Province(BE2016398)~~
文摘The yield and yield components of Japonica variety Tongjing 981 under different density and fertilization levels were studied through regression and correlation and path analysis. The results showed that the number of panicles per unit area, number of filled grains per panicle and 1 000-grain weight all had very significant yield increasing effects, and the number of panicles per unit area played a leading role. However, the yield increasing effects of the number of panicles per unit area and number of filled grains per panicle are equally important when the basic seedlings are more or the N fertilizer application rate is large. In practical production, a major factor should be determined among the yield components, and rational cultivation measures should be taken accordingly, to improve yield.
文摘Many researches showed a comprehensive assessment of the cropping practice effect on greenhouse gas （GHG） emissions per unit yield （yield-scaled） rather than per the land area （area-scaled）, and it was noteworthy that cropping practices decided to increase or decrease grain yield, and reduce or promote greenhouse gas emissions. In this study, a meta-analysis was conducted to quantify the effects of rice basic seedlings （BS） on the global warming potential （GWP） of GHG emissions at the yield-scale in China. The results suggested that significant difference was observed in yield-scaled GWP of BS. The lowest yield-scaled GWP occurred at 80-100 BS （415.65 kg CO2 equiv/mg）. The yield-scaled GHG emission from high to low was that of the hybrid rice varieties （1 028.86 kg CO2 equiv/mg）, the conventional rice varieties （634.15 kg CO2 equiv/mg） and the super rice varieties （576.57 kg CO2 equiv/mg）. Consequently, the model of conventional rice varieties and super rice varieties at 80-100 BS could be a scientifc method of matching inthe rice cropping system. A further assessment of rice density and variety impacts on GHG emissions at yield-scale was urgently needed to develop, so as to achieve win-win policies of rice production for higher yield with lower emissions.
文摘To detect retrospectively the phenotype and stability of the E-protein gene in Japanese Encephalitis （JE） virus strain SA14-14-2 used in the live-attenuated JE vaccine prepears, the viral titer was titrated by plaque formation in BHK-21 cell cultures, and the neuro-virulence of viruses was assayed in mice with body weight of 12-14 g by intracerebral inoculation. Meanwhile, the total RNA of virus gene was extracted and amplified by RT-PCR with the designed primers, and then it was purified and cloned to the expression vector pGEM-T. The recombinant plasmid was purified and sequenced. It was found that the loss of viral titer of vaccines stored in -20℃ for longer than 10 years was less than 0.5 Lg PFU/ml. No mice inoculated intracerebrally showed signs of illness or even death. The size of plagues of the vaccine virus remained to be small, and the E genes of primary virus seed SA14-14-2 and the vaccines prepared at different years （1987-2001） were unchanged, in- cluding the 8 critical amino acid sites which were different from the parent wild virus strain SA14 and the related neuro-virulence. These results indicate that the genotypic and biological characteristics of the attenuated JE virus strain SA14-14-2 and its vaccines sion noted. prepared are quite stable without any reversion noted.
文摘The purpose of this study was to understand the stability and possibility of back mutation of Japanese encephalitis （JE） attenuated vaccine virus strain SA14-14-2 HKs on molecular level. The E genes of the SA14-14-2 HKs vaccine virus and its PHK cells passaged virus （SA14-14-2 HK17 ）, its mouse brain passaged virus （SA14-14-2 SM1 ） were sequenced and compared with the E gene of parental SAI4 virus. The total RNA was extracted from infected Vero cells and amplified by RT-PCR. The RT-PCR products were purified and cloned into T-vector. Positive clones were screened, identified and sequenced. There were twelve nucleotides and eight amino acids substitutions between SA14 parent virus and SA14-34-2 PHKs vaccine virus. The SA14-14-2 PHK17 virus showed two additional mutations （E-331 and E-398） which were not back mutations. Although five additional mutations were found in SA14-34-2 SMt virus, only one （E-307） was back mutation. Genetic characteristics of the attenuated vaccine virus SA14- 34-2 were stable when it was passaged 37 times on PHK cells or one time in mouse brains.
文摘The study was aimed at evaluating growth response of Heteroclarias fingerlings fed diet in which fish meal was substituted with graded levels of earthworm meal. The replacement levels were 0.00%, 25%, 50%, 75% and 100% designated as Eo, E25, Es0, E75 and El00, respectively. Fingerlings used for the work were obtained through artificial insemination of brood stock （purchased from local farmers） with ovaprim in the laboratory. The resulting fry were reared and fed with cultured plankton for 2 weeks followed by 100% fish meal for another two weeks. Thereafter sixteen fingerlings weighing 4.73 g and measuring 6.512 mm standard length （on the average） were starved over night and reared in five indoors tanks （0.8 ~ 0.5 ~ 0.5 m） in duplicate for eight weeks. Fingerlings were fed on graded earthworm meals of 40% protein twice daily at 08：00 and 16：00. The highest mean weight （6.77 g）, specific growth rate （0.86） and protein efficiency ratio （0.6） were obtained at 50% replacement level. Also, Food conversion ratio was the highest at 50% substitution level and lowest at 0.00% substitution, indicating that fingerlings use earthworm containing meal more efficiently. Furthermore, cost benefit analysis revealed that the profit index for 50% inclusion of earthworm meal was the highest （1.71） and the highest net profit of N374.32 （circa $2.3） was achieved at this level. Water quality parameters observed were within tolerable values for the fingerlings well being. Consequently, farmers are advised to use 50% earthworm meal in place of fish meal for formulation of Heteroclarias fingerlings diet. This will drastically reduce production cost, increase farmers profit and enhance the biological value of our menu.
文摘Almost three-fourths of forests are experiencing anthropogenic disturbances globally, and more than two-thirds of the forests in Nepal receive different types of disturbances. In community forests(CFs), local communities are dependent on the ecosystem services provided by the forests for various aspects of their livelihoods, which disturb the forests’ natural conditions and ecosystem functioning in a variety of ways. This study tested the major disturbance factors that had influential roles on plant species diversity, recruitment(seedlings and saplings), biomass, soil organic carbon(SOC) and total carbon density in two community-managed forests in the Mid-hills of Nepal. The stump number, cut-off seedlings and saplings, lopping, dropping, and grazing/trampling were used as measures of the major anthropogenic disturbances. The necessary data were collected from 89 randomly selected sample plots, each with an area of 250 m2. The responses to anthropogenic disturbances were analyzed using Generalized Linear Models(GLM). The results showed that forest lopping was the most significant anthropogenic disturbance for biomass and total carbon density balance. A higher degree of lopping in the forests resulted in a lowering of the forests’ carbon stock in the study area. SOC showed no significant response to any of the tested anthropogenic disturbances. Woody species richness and number of saplings increased with an increasing number of stumps, which signifies that intermediate disturbance was beneficial. However, a higher intensity of lopping reduced the sapling density. Grazing/trampling was the most significant disturbance for inhibiting seedling growth. Areas in the forests with a higher intensity of trampling showed lower numbers of seedlings and saplings. These results will be a guide for managing anthropogenic disturbances in multiple-use forests in Nepal, as well as those in similar socio-economic environments worldwide.
基金Supported by the National Natural Science Foundation of China (No.4002101)
文摘Pinus tabulaeformis seedlings were grown under a factorial design to measure biomass accumulation and P, Na and K concentrations of plants, with 3 different ectomycorrhizal fungus (EMF) strains (Boletus edulis, Xerocomus chrysenteron and Gomphidius viscidus) and two P treatments (with or without extra P). Growth and mineral nutrition of pine seedlings were stimulated by three EMF under salinity stress. Na concentrations were changed and plant K and P concentrations were increased significantly by EMF. Adding extra P made no difference in accumulation of seedlings biomass, and did not assist element absorption of plants. Although three strains of EMF can all enhance the tolerance of pine seedlings to salinity stress, they may utilize different mechanisms because of different performance in absorption of elements. The increased P and K accumulation and the balance of ion concentrations might be due to the enhanced tolerance of EMF-inoculated plants to saline conditions.
基金J. Wang acknowledges partial support from the National Science Foundation under Grant Nos. 0813691 and 1216936. Z. Mukandavire was supported by the UF Science for Life Program, an interdisciplinary program with support from the Howard Hughes Medical Institute. The authors would like to thank the anonymous referees for helpful comments.
文摘The use of cholera vaccines has been increasingly recognized as an effective control measure in cholera endemic countries. However, guidelines for using vaccination during cholera outbreaks are still to be established, and it remains an open question as to how and when the vaccines should be deployed to best control ongoing cholera outbreaks. Here we formulate a new optimal control model to assess the value of cholera vaccines in epidemic settings and cost-effective optimal times to deploy a vaccine. Our results suggest that as long as the vaccine prices are sufficiently low, vaccination should always start from or immediately after the onset of a cholera outbreak.
