The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa, communities in the Inner M...The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa, communities in the Inner Mongolia Plateau. The research work was based on a 12-year study (from 1984 to 1995) of species abundance, diversity, and primary productivity of four Stipa communities, i.e. S. baicalensis Roshev., S. grandis P. Smirn., S, krylovii Roshev., and S. klemenzii Roshev. respectively. The Shnnon-Wiener index was used as a measurement of plant diversity, while functional composition was used to differentiate the functional groups that were included in the communities. The plant species of four Stipa communities were classified into functional groups based on the differences in life forms and ecological groups, which influence their performance in resource requirements, seasonality of growth, tolerance to water stress, and life history. Plant species were classified into five functional groups based on their differences in life form, shrubs and half shrubs, perennial bunch grasses, perennial rhizome grasses, forbs, annuals and biennials. Based on their differences in water requirement these species were classified into four functional groups: xerads, intermediate xerads, intermediate mesophytes, and mesophytes. The results showed: 1) Plant species diversity stabilized ecosystem processes. Shannon-Wiener index were 2.401 4, 2.172 0, 1.624 8, 0.354 3 from S. baicalensis community to S. grandis, S. krylovii and S. klemenzii community, respectively. The dynamics of the aboveground net primary productivity (ANPP) for a 12-year's period showed a reverse pattern, the coefficients of variation of the four communities were 21.94%, 20.63%, 29.21% and 39.72% respectively. 2) The Life form functional group component of diversity was a greater determinant of the ecosystem processes than the species component of diversity. The effects of perennial bunch grasses, perennial rhizome grasses and forbs on community stability were highly significant. 3) The ecological group component of diversity was also a great determinant of the ecosystem processes. The effects of xerads, intermediate xerads, and mesophytes on community stability were also very strong.展开更多
Among the many approaches for studying the net primary productivity (NPP), a new method by using remote sensing was introduced in this paper. With spectral information source (the visible band, near infrared band and ...Among the many approaches for studying the net primary productivity (NPP), a new method by using remote sensing was introduced in this paper. With spectral information source (the visible band, near infrared band and thermal infrared band) of NOAA-AVHRR, we can get the relative index and parameters, which can be used for estimating NPP of terrestrial vegetation. By means of remote sensing, the estimation of biomass and NPP is mainly based on the models of light energy utilization. In other words, the biomass and NPP can be calculated from the relation among NPP, absorbed photosynthetical active radiation (APAR) and the rate (epsilon) of transformation of APAR to organic matter, thus: NPP = ( FPAR x PAR) x [epsilon * x sigma (T) x sigma (E) x sigma (S) x (1 - Y-m) x (1 - Y-g)]. Based upon remote sensing ( RS) and geographic information system (GIS), the NPP of terrestrial vegetation in China in every ten days was calculated, and the annual NPP was integrated. The result showed that the total NPP of terrestrial vegetation in China was 6.13 x 10(9) t C . a(-1) in 1990 and the maximum NPP was 1 812.9 g C/m(2). According to this result, the spatio-temporal distribution of NPP was analyzed. Comparing to the statistical models, the RS model, using area object other than point one, can better reflect the distribution of NPP, and match the geographic distribution of vegetation in China.展开更多
Sustainable forage production is one of the most important factors in livestock production system. Smallholder livestock production system is a part of agricultural practice in Indonesia. Limited land owned by farmers...Sustainable forage production is one of the most important factors in livestock production system. Smallholder livestock production system is a part of agricultural practice in Indonesia. Limited land owned by farmers was dominantly cultivated for food crops, and very small part of it used for cultivating forage plants. This leads to restriction of smallholder livestock development, because no more land available for forage production. Integrated forage production system by planting forage plants and food crops or trees in the same area becomes a considerable cropping system that widely practiced by the farmers in Indonesia. Some grasses and legumes have morphological advantages overcoming growth condition under shading. These growth characteristics are benefit in designing compatible system components for enhanced productivity in tree-pasture systems. Four potential shade-tolerant creeping forages that were combined with 2 levels of nitrogen application were tested using factorial completely randomized design 3 replicates. The first factor was species of creeping forages (stoloniferous): BH = Brachiaria humidicola, PN = Paspalum notatum, AC - Axonopus compressus and, AP = Arachis pintoi. The second factor was nitrogen (urea) fertilizer: A = without N fertilizer and B = with N fertilizer (300 kg Urea/ha). The observations included the growth rates of plant length, plant length, number of leaves, herbages yield (shoot), root dry weight, senescence, total N-shoot, N-soil and N-uptake. The results showed that growth characteristics and productivity of creeping forage plants was significantly differed by the species. Most species showed an increase in growth trend, except P. notatum. A. compressus significantly showed as the best performance species compared to other, in terms of growth rates, plant length, number of leaves, herbage yield (shoot) and root dry weight, N-uptake and N-shoot. This was lbllowed by B. humidicola, P. notatum, and A. pintoi. Based on previous study, A. compressus found as one of the native species in most tree system. It indicated its superior growth compared to other species tested. However, it is needed further research to observe the compatibility of each species in tree-pasture systems.展开更多
Aims Seasonal variations in species richness,aboveground net primary productivity(ANPP)and stability under resource enrichment are frequently ignored.This study explores how the impacts of resource enrichment on speci...Aims Seasonal variations in species richness,aboveground net primary productivity(ANPP)and stability under resource enrichment are frequently ignored.This study explores how the impacts of resource enrichment on species richness,ANPP and stability vary among seasons in semi-arid grasslands.Methods We conducted a 3-year experiment in an Inner Mongolia grassland to determine the effects of resource input(water[W],nitrogen[N])on species richness,community ANPP and stability using seasonal sampling during the growing season(2013–2015).Structural equation modeling(SEM)was used to examine the relative importance of resource input on community stability via mechanistic pathways in each month and the whole growing season.Important Findings Resource inputs did not affect community ANPP in May and June,while N and/or NW enhanced ANPP in July and August.Resource inputs generally did not affect species richness,asynchrony or community stability in most of the time.Positive responses of perennial bunchgrasses(PB)to N and/or NW treatments contributed to the increased community ANPP in July and August.Species asynchrony may be the major mechanism contributing to community stability in May and June and the entire growing season,and PB stability is potentially the primary factor controlling community stability in July and August under resource enrichment.Our results indicate that season and resource availability could interact to regulate species richness,community ANPP and stability in semi-arid grasslands.These findings have important implications for management practices in semi-arid grasslands in order to mitigate the impact of land use and global change.展开更多
The human pathogen, group A rotavirus, is the most prevalent cause of acute infantile and pediatric gastroenteritis worldwide, especially in developing countries. There is an urgent demand for safer, more effective an...The human pathogen, group A rotavirus, is the most prevalent cause of acute infantile and pediatric gastroenteritis worldwide, especially in developing countries. There is an urgent demand for safer, more effective and cheaper vaccines against rotavirus infection. Plant-derived antigens may provide an exclusive way to produce economical subunit vaccines. Virus-like particles, constituting viral capsid proteins without viral nucleic acids, are considered a far safer candidate compared with live attenuated viral vaccines. In this study, the rotavirus capsid proteins VP2, VP6 and VP7 were co-expressed in transgenic tobacco plants, and their expression levels, formation of rotavirus-like particles (RV VLPs) and immunogenicity were extensively studied. Quantitative real-time RT-PCR and Western blot analysis revealed that the expression level of vp6 was the highest while vp7 was expressed at the lowest levels. The RV VLPs were purified from transgenic tobacco plants and analyzed by electron microscopy and Western blot. Results indicated that the plant-derived VP2, VP6 and VP7 proteins self-assembled into 2/6 or 2/6/7 RV VLPs with a diameter of 60-80 nm. When orally delivered into mice with cholera toxin as an adjuvant, the total soluble protein extracted from transgenic tobacco plants induced rotavirus-specific antibodies comparable with those of attenuated rotavirus vaccines, while VP 2/6/7 induced higher serum IgG and fecal IgA titers compared with VP 2/6.展开更多
Aims Intensive land management practices can compromise soil biodiversity,thus jeopardizing long-term soil productivity.Arbuscular mycorrhizal fungi(AMF)play a pivotal role in promoting soil productivity through oblig...Aims Intensive land management practices can compromise soil biodiversity,thus jeopardizing long-term soil productivity.Arbuscular mycorrhizal fungi(AMF)play a pivotal role in promoting soil productivity through obligate symbiotic associations with plants.However,it is not clear how properties of plant communities,especially species richness and composition influence the viability of AMF populations in soils.Methods Here we test whether monocultures of eight plant species from different plant functional groups,or a diverse mixture of plant species,maintain more viable AMF propagules.To address this question,we extracted AMF spores from 12-year old plant monocultures and mixtures and paired single AMF spores with single plants in a factorial design crossing AMF spore origin with plant species identity.Important Findings AMF spores from diverse plant mixtures were more successful at colonizing multiple plant species and plant individuals than AMF spores from plant monocultures.Furthermore,we found evidence that AMF spores originating from diverse mixtures more strongly increased biomass than AMF from monocultures in the legume Trifolium repens L.AMF viability and ability to interact with many plant species were greater when AMF spores originated from 12-year old mixtures than monocultures.Our results show for the first time that diverse plant communities can sustain AMF viability in soils and demonstrate the potential of diverse plant communities to maintain viable AMF propagules that are a key component to soil health and productivity.展开更多
Biodiversity research has shown that primary productivity increases with plant species number,especially in many experimental grassland systems.Here,we assessed the correlation between productivity and diversity of ph...Biodiversity research has shown that primary productivity increases with plant species number,especially in many experimental grassland systems.Here,we assessed the correlation between productivity and diversity of phytophages and natural enemy assemblages associated with planting date and intercropping in four cotton agroecosystems.Twenty-one pairs of data were used to determine Pearson correlations between species richness,total number of individuals,diversity indices and productivity for each assemblage every five days from 5 June to 15 September 2012.At the same trophic level,the productivity exhibited a significant positive correlation with species richness of the phytophage or predator assemblage.A significant correlation was found between productivity and total number of individuals in most cotton fields.However,no significant correlations were observed between productivity and diversity indices(including indices of energy flow diversity and numerical diversity)in most cotton fields for either the phytophage or the predator assemblages.Species richness of phytophage assemblage and total individual numbers were significantly correlated with primary productivity.Also,species richness of natural enemy assemblage and total number of individuals correlated with phytophage assemblage productivity.A negative but not significant correlation occurred between the indices of numerical diversity and energy flow diversity and lower trophic-level productivity in the cotton-phytophage and phytophage-predator assemblages for most intercropped cotton agroecosystems.Our results clearly showed that there were no correlations between diversity indices and productivity within the same or lower trophic levels within the phytophage and predator assemblages in cotton agroecosystems,and inter-cropped cotton fields had a stronger ability to support the natural enemy assemblage and potentially to reduce phytophages.展开更多
文摘The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa, communities in the Inner Mongolia Plateau. The research work was based on a 12-year study (from 1984 to 1995) of species abundance, diversity, and primary productivity of four Stipa communities, i.e. S. baicalensis Roshev., S. grandis P. Smirn., S, krylovii Roshev., and S. klemenzii Roshev. respectively. The Shnnon-Wiener index was used as a measurement of plant diversity, while functional composition was used to differentiate the functional groups that were included in the communities. The plant species of four Stipa communities were classified into functional groups based on the differences in life forms and ecological groups, which influence their performance in resource requirements, seasonality of growth, tolerance to water stress, and life history. Plant species were classified into five functional groups based on their differences in life form, shrubs and half shrubs, perennial bunch grasses, perennial rhizome grasses, forbs, annuals and biennials. Based on their differences in water requirement these species were classified into four functional groups: xerads, intermediate xerads, intermediate mesophytes, and mesophytes. The results showed: 1) Plant species diversity stabilized ecosystem processes. Shannon-Wiener index were 2.401 4, 2.172 0, 1.624 8, 0.354 3 from S. baicalensis community to S. grandis, S. krylovii and S. klemenzii community, respectively. The dynamics of the aboveground net primary productivity (ANPP) for a 12-year's period showed a reverse pattern, the coefficients of variation of the four communities were 21.94%, 20.63%, 29.21% and 39.72% respectively. 2) The Life form functional group component of diversity was a greater determinant of the ecosystem processes than the species component of diversity. The effects of perennial bunch grasses, perennial rhizome grasses and forbs on community stability were highly significant. 3) The ecological group component of diversity was also a great determinant of the ecosystem processes. The effects of xerads, intermediate xerads, and mesophytes on community stability were also very strong.
文摘Among the many approaches for studying the net primary productivity (NPP), a new method by using remote sensing was introduced in this paper. With spectral information source (the visible band, near infrared band and thermal infrared band) of NOAA-AVHRR, we can get the relative index and parameters, which can be used for estimating NPP of terrestrial vegetation. By means of remote sensing, the estimation of biomass and NPP is mainly based on the models of light energy utilization. In other words, the biomass and NPP can be calculated from the relation among NPP, absorbed photosynthetical active radiation (APAR) and the rate (epsilon) of transformation of APAR to organic matter, thus: NPP = ( FPAR x PAR) x [epsilon * x sigma (T) x sigma (E) x sigma (S) x (1 - Y-m) x (1 - Y-g)]. Based upon remote sensing ( RS) and geographic information system (GIS), the NPP of terrestrial vegetation in China in every ten days was calculated, and the annual NPP was integrated. The result showed that the total NPP of terrestrial vegetation in China was 6.13 x 10(9) t C . a(-1) in 1990 and the maximum NPP was 1 812.9 g C/m(2). According to this result, the spatio-temporal distribution of NPP was analyzed. Comparing to the statistical models, the RS model, using area object other than point one, can better reflect the distribution of NPP, and match the geographic distribution of vegetation in China.
文摘Sustainable forage production is one of the most important factors in livestock production system. Smallholder livestock production system is a part of agricultural practice in Indonesia. Limited land owned by farmers was dominantly cultivated for food crops, and very small part of it used for cultivating forage plants. This leads to restriction of smallholder livestock development, because no more land available for forage production. Integrated forage production system by planting forage plants and food crops or trees in the same area becomes a considerable cropping system that widely practiced by the farmers in Indonesia. Some grasses and legumes have morphological advantages overcoming growth condition under shading. These growth characteristics are benefit in designing compatible system components for enhanced productivity in tree-pasture systems. Four potential shade-tolerant creeping forages that were combined with 2 levels of nitrogen application were tested using factorial completely randomized design 3 replicates. The first factor was species of creeping forages (stoloniferous): BH = Brachiaria humidicola, PN = Paspalum notatum, AC - Axonopus compressus and, AP = Arachis pintoi. The second factor was nitrogen (urea) fertilizer: A = without N fertilizer and B = with N fertilizer (300 kg Urea/ha). The observations included the growth rates of plant length, plant length, number of leaves, herbages yield (shoot), root dry weight, senescence, total N-shoot, N-soil and N-uptake. The results showed that growth characteristics and productivity of creeping forage plants was significantly differed by the species. Most species showed an increase in growth trend, except P. notatum. A. compressus significantly showed as the best performance species compared to other, in terms of growth rates, plant length, number of leaves, herbage yield (shoot) and root dry weight, N-uptake and N-shoot. This was lbllowed by B. humidicola, P. notatum, and A. pintoi. Based on previous study, A. compressus found as one of the native species in most tree system. It indicated its superior growth compared to other species tested. However, it is needed further research to observe the compatibility of each species in tree-pasture systems.
基金This work was supported by the National Natural Science Foundation of China(31630010 and 31320103916).
文摘Aims Seasonal variations in species richness,aboveground net primary productivity(ANPP)and stability under resource enrichment are frequently ignored.This study explores how the impacts of resource enrichment on species richness,ANPP and stability vary among seasons in semi-arid grasslands.Methods We conducted a 3-year experiment in an Inner Mongolia grassland to determine the effects of resource input(water[W],nitrogen[N])on species richness,community ANPP and stability using seasonal sampling during the growing season(2013–2015).Structural equation modeling(SEM)was used to examine the relative importance of resource input on community stability via mechanistic pathways in each month and the whole growing season.Important Findings Resource inputs did not affect community ANPP in May and June,while N and/or NW enhanced ANPP in July and August.Resource inputs generally did not affect species richness,asynchrony or community stability in most of the time.Positive responses of perennial bunchgrasses(PB)to N and/or NW treatments contributed to the increased community ANPP in July and August.Species asynchrony may be the major mechanism contributing to community stability in May and June and the entire growing season,and PB stability is potentially the primary factor controlling community stability in July and August under resource enrichment.Our results indicate that season and resource availability could interact to regulate species richness,community ANPP and stability in semi-arid grasslands.These findings have important implications for management practices in semi-arid grasslands in order to mitigate the impact of land use and global change.
基金supported by the National High Technology Research and Development Program of China (Grant No. 2007AA100505)
文摘The human pathogen, group A rotavirus, is the most prevalent cause of acute infantile and pediatric gastroenteritis worldwide, especially in developing countries. There is an urgent demand for safer, more effective and cheaper vaccines against rotavirus infection. Plant-derived antigens may provide an exclusive way to produce economical subunit vaccines. Virus-like particles, constituting viral capsid proteins without viral nucleic acids, are considered a far safer candidate compared with live attenuated viral vaccines. In this study, the rotavirus capsid proteins VP2, VP6 and VP7 were co-expressed in transgenic tobacco plants, and their expression levels, formation of rotavirus-like particles (RV VLPs) and immunogenicity were extensively studied. Quantitative real-time RT-PCR and Western blot analysis revealed that the expression level of vp6 was the highest while vp7 was expressed at the lowest levels. The RV VLPs were purified from transgenic tobacco plants and analyzed by electron microscopy and Western blot. Results indicated that the plant-derived VP2, VP6 and VP7 proteins self-assembled into 2/6 or 2/6/7 RV VLPs with a diameter of 60-80 nm. When orally delivered into mice with cholera toxin as an adjuvant, the total soluble protein extracted from transgenic tobacco plants induced rotavirus-specific antibodies comparable with those of attenuated rotavirus vaccines, while VP 2/6/7 induced higher serum IgG and fecal IgA titers compared with VP 2/6.
基金supported by the German Research Foundation(RO2397/7)conducted in the framework of the Jena Experiment(FOR 456/1451)+1 种基金with additional support from the Friedrich Schiller University of JenaFurther support was provided by the German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig,funded by the German Research Foundation(FZT 118).
文摘Aims Intensive land management practices can compromise soil biodiversity,thus jeopardizing long-term soil productivity.Arbuscular mycorrhizal fungi(AMF)play a pivotal role in promoting soil productivity through obligate symbiotic associations with plants.However,it is not clear how properties of plant communities,especially species richness and composition influence the viability of AMF populations in soils.Methods Here we test whether monocultures of eight plant species from different plant functional groups,or a diverse mixture of plant species,maintain more viable AMF propagules.To address this question,we extracted AMF spores from 12-year old plant monocultures and mixtures and paired single AMF spores with single plants in a factorial design crossing AMF spore origin with plant species identity.Important Findings AMF spores from diverse plant mixtures were more successful at colonizing multiple plant species and plant individuals than AMF spores from plant monocultures.Furthermore,we found evidence that AMF spores originating from diverse mixtures more strongly increased biomass than AMF from monocultures in the legume Trifolium repens L.AMF viability and ability to interact with many plant species were greater when AMF spores originated from 12-year old mixtures than monocultures.Our results show for the first time that diverse plant communities can sustain AMF viability in soils and demonstrate the potential of diverse plant communities to maintain viable AMF propagules that are a key component to soil health and productivity.
基金supported by the National Natural Science Foundation of China(31101491,31030012)National Key Technology R&D Program(2012BAD19B05)
文摘Biodiversity research has shown that primary productivity increases with plant species number,especially in many experimental grassland systems.Here,we assessed the correlation between productivity and diversity of phytophages and natural enemy assemblages associated with planting date and intercropping in four cotton agroecosystems.Twenty-one pairs of data were used to determine Pearson correlations between species richness,total number of individuals,diversity indices and productivity for each assemblage every five days from 5 June to 15 September 2012.At the same trophic level,the productivity exhibited a significant positive correlation with species richness of the phytophage or predator assemblage.A significant correlation was found between productivity and total number of individuals in most cotton fields.However,no significant correlations were observed between productivity and diversity indices(including indices of energy flow diversity and numerical diversity)in most cotton fields for either the phytophage or the predator assemblages.Species richness of phytophage assemblage and total individual numbers were significantly correlated with primary productivity.Also,species richness of natural enemy assemblage and total number of individuals correlated with phytophage assemblage productivity.A negative but not significant correlation occurred between the indices of numerical diversity and energy flow diversity and lower trophic-level productivity in the cotton-phytophage and phytophage-predator assemblages for most intercropped cotton agroecosystems.Our results clearly showed that there were no correlations between diversity indices and productivity within the same or lower trophic levels within the phytophage and predator assemblages in cotton agroecosystems,and inter-cropped cotton fields had a stronger ability to support the natural enemy assemblage and potentially to reduce phytophages.