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 w展开更多
In 1997, we conducted a vegetation survey in three semi-arid natural grasslands （steppes） with different livestock grazing intensities in Southwest Heilongjiang Province, China, The dominant grassland species was th...In 1997, we conducted a vegetation survey in three semi-arid natural grasslands （steppes） with different livestock grazing intensities in Southwest Heilongjiang Province, China, The dominant grassland species was the grass Stipa baicalensis Roshev. Grasslands with light, intermediate, and heavy grazing intensities were located 10, 5, and 2 km from a village, respectively. Villagers use the steppe to raise cattle, horses, sheep, and goats. Each of the three grasslands was surveyed by placing 100 quadrats （50 cm×50 cm） along a 50 m line transect. Each quadrat was divided into four equal areas （25 cm×25 cm; S-quadrats） and all plant species occurring in each of these smaller areas were identified and recorded. These data were summarized into frequency distributions and the percentage of S-quadrats containing a given species and the variance of each species were estimated. The power law was applied to these estimates. The power law was used to evaluate the spatial heterogeneity and frequency of occurrence for each species in the grassland community. The lightly grazed grassland exhibited high spatial heterogeneity （caused by large plant size）, the highest species diversity, and a high occurrence of S. baicalensis. In contrast, the heavily grazed grassland exhibited high spatial heterogeneity （caused by patchy populations of small plant size）, low species diversity, and a low occurrence of S. baicalensis. We judged that the heavily grazed grassland was overgrazed and exclusion of livestock from the degraded areas is necessary for recovery.展开更多
The mechanisms driving changes in dominant plant species are the key for understanding how grassland ecosystems respond to climate change.In this study,we examined plant functional traits（morphological characteristic...The mechanisms driving changes in dominant plant species are the key for understanding how grassland ecosystems respond to climate change.In this study,we examined plant functional traits（morphological characteristics：plant height,leaf area,and leaf number;biomasses：aboveground,belowground,and total;and growth indices：root-to-shoot ratio,specific leaf area,and leaf mass ratio） of four zonal Stipa species（S.baicalensis,S.bungeana,S.grandis,and S.breviflora） from Inner Mongolian grassland in response to warming（control,＋1.5,＋2.0,＋4.0,and ＋6.0℃）,changing precipitation（-30%,-15%,control,＋15%,and＋30%）,and their combined effects via climate control chambers.The results showed that warming and changing precipitation had significant interactive effects,different from the accumulation of single-factor effects,on functional traits of Stipa species.The correlation and sensitivity of different plant functional traits to temperature and precipitation differed.Among the four species,the accumulation and variability of functional traits had greater partial correlation with precipitation than temperature,except for leaf number,leaf area,and specific leaf area,in S.breviflora,S.bungeana,and S.grandis.For S.baicalensis,the accumulation and variability of plant height,aboveground biomass,and root-to-shoot ratio only had significant partial correlation with precipitation.However,the variability of morphological characteristics,biomasses,and some growth indices,was more sensitive to temperature than precipitation in S.bungeana,S.grandis,and S.breviflora—except for aboveground biomass and plant height.These results reveal that precipitation is the key factor determining the growth and changes in plant functional traits in Stipa species,and that temperature mainly influences the quantitative fluctuations of the changes in functional traits.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 w
文摘In 1997, we conducted a vegetation survey in three semi-arid natural grasslands （steppes） with different livestock grazing intensities in Southwest Heilongjiang Province, China, The dominant grassland species was the grass Stipa baicalensis Roshev. Grasslands with light, intermediate, and heavy grazing intensities were located 10, 5, and 2 km from a village, respectively. Villagers use the steppe to raise cattle, horses, sheep, and goats. Each of the three grasslands was surveyed by placing 100 quadrats （50 cm×50 cm） along a 50 m line transect. Each quadrat was divided into four equal areas （25 cm×25 cm; S-quadrats） and all plant species occurring in each of these smaller areas were identified and recorded. These data were summarized into frequency distributions and the percentage of S-quadrats containing a given species and the variance of each species were estimated. The power law was applied to these estimates. The power law was used to evaluate the spatial heterogeneity and frequency of occurrence for each species in the grassland community. The lightly grazed grassland exhibited high spatial heterogeneity （caused by large plant size）, the highest species diversity, and a high occurrence of S. baicalensis. In contrast, the heavily grazed grassland exhibited high spatial heterogeneity （caused by patchy populations of small plant size）, low species diversity, and a low occurrence of S. baicalensis. We judged that the heavily grazed grassland was overgrazed and exclusion of livestock from the degraded areas is necessary for recovery.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund(GYHY201506001-3)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05050408)National(Key)Basic Research and Development(973)Program of China(2010CB951300)
文摘The mechanisms driving changes in dominant plant species are the key for understanding how grassland ecosystems respond to climate change.In this study,we examined plant functional traits（morphological characteristics：plant height,leaf area,and leaf number;biomasses：aboveground,belowground,and total;and growth indices：root-to-shoot ratio,specific leaf area,and leaf mass ratio） of four zonal Stipa species（S.baicalensis,S.bungeana,S.grandis,and S.breviflora） from Inner Mongolian grassland in response to warming（control,＋1.5,＋2.0,＋4.0,and ＋6.0℃）,changing precipitation（-30%,-15%,control,＋15%,and＋30%）,and their combined effects via climate control chambers.The results showed that warming and changing precipitation had significant interactive effects,different from the accumulation of single-factor effects,on functional traits of Stipa species.The correlation and sensitivity of different plant functional traits to temperature and precipitation differed.Among the four species,the accumulation and variability of functional traits had greater partial correlation with precipitation than temperature,except for leaf number,leaf area,and specific leaf area,in S.breviflora,S.bungeana,and S.grandis.For S.baicalensis,the accumulation and variability of plant height,aboveground biomass,and root-to-shoot ratio only had significant partial correlation with precipitation.However,the variability of morphological characteristics,biomasses,and some growth indices,was more sensitive to temperature than precipitation in S.bungeana,S.grandis,and S.breviflora—except for aboveground biomass and plant height.These results reveal that precipitation is the key factor determining the growth and changes in plant functional traits in Stipa species,and that temperature mainly influences the quantitative fluctuations of the changes in functional traits.
