Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass（AGB）, biodiversity and community stabil...Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass（AGB）, biodiversity and community stability associated with different management practices were studied with a three-year field investigation in a temperate steppe of Inner Mongolia, China. The species richness, Shannon-Wiener index, evenness, plant functional type abundance, AGB, temporal community stability, summed covariance, scaling coefficient and dominant species stability were compared among areas subjected to long-term reservation（R）, long-term grazing（G）, mowing since enclosure in 2008（M） and grazing enclosure since 2008（E）. Site R had higher perennial grass abundance and lower species richness than sites G, M and E, although the AGB was not significantly different among the four sites. The species structure varied from a single dominant species at site R to multiple dominant species at sites G, M and E. The long-term reservation grassland had lower biodiversity but higher stability, whereas the enclosed grassland with/without mowing had higher biodiversity but lower stability. Different stability mechanisms, such as the compensatory dynamics, mean-variance scaling and dominant species stability were examined. Results showed that community stability was most closely related to the relative stability of the dominant species, which supports the biomass ratio hypothesis proposed by Grime.展开更多
In order to test whether density dependence influences community diversity, a combination of manipulative experimentation and plot surveys were done using Cryptocarya concinna, a dominant species in subtropical evergr...In order to test whether density dependence influences community diversity, a combination of manipulative experimentation and plot surveys were done using Cryptocarya concinna, a dominant species in subtropical evergreen forest. Twelve pairs of 1 m^2 seedling plots were built around 12 adults, and plots were treated monthly with either a fungicide or a control. The surviving proportion of C. concinna seedlings at different stages was calculated, and an analysis was conducted on the impact of fungicide on seedling survival and species richness. Correlation between relative abundance and community evenness at different ages was analyzed using plot surveys. The results showed that fungicide treatment decreased species richness of the seedling community by pro- moting the recruitment of common species. Furthermore, census of a 25 m radius around adult C. concinna trees confirmed that the density of saplings increased with distance from adults. Relative abundance of C. concinna decreased with increasing age, and decreasing C. concinna dominance resulted in an increase in community even- ness. To avoid the appearance of a single optimum population, the dominance of C. concinna decreased with age via density dependence, and subsequently improved community species diversity.展开更多
以黄土丘陵区退耕草地群落典型优势种白羊草、长芒草和达乌里胡枝子为研究对象,测定不同氮磷(主区N:0,50,100 kg N hm^(-2)a^(-1);副区P:0,40,80 kg P_(2)O_(5) hm^(-2)a^(-1))添加处理下叶片光合气体交换参数、叶绿素荧光参数、叶片氮...以黄土丘陵区退耕草地群落典型优势种白羊草、长芒草和达乌里胡枝子为研究对象,测定不同氮磷(主区N:0,50,100 kg N hm^(-2)a^(-1);副区P:0,40,80 kg P_(2)O_(5) hm^(-2)a^(-1))添加处理下叶片光合气体交换参数、叶绿素荧光参数、叶片氮磷含量、光合氮利用效率(PNUE)和光合磷利用效率(PPUE),探究不同优势种光合生理特征对外源氮磷添加的响应特征与物种差异。结果表明:单独氮添加下,3个优势种的净光合速率(P_(n))、蒸腾速率、水分利用效率(WUE_(i))、气孔限制值(Ls)和光系统Ⅱ(PSⅡ)活性高于或显著高于未施肥处理,白羊草和达乌里胡枝子的PNUE和PPUE以及长芒草的PPUE显著增加。单独磷添加下,仅达乌里胡枝子的P_(n)、WUE_(i)、Ls和PNUE相比未施肥处理显著增加。氮磷共同添加下,50 kg N hm^(-2)a^(-1)处理下,施磷后达乌里胡枝子的P_(n)以及三个优势种的PNUE显著增加,白羊草的PPUE显著降低;100 kg N hm^(-2)a^(-1)处理下,施磷后达乌里胡枝子的P_(n)和PNUE均显著增加,白羊草PPUE和长芒草的PNUE的仅在40 kg P_(2)O_(5) hm^(-2)a^(-1)处理下显著增加。3个优势种的P_(n)均与PSⅡ最大光化学效率和叶片氮含量呈显著正相关关系,长芒草和达乌里胡枝子的P_(n)与PSⅡ潜在活性和叶片磷含量呈显著正相关关系。总体表明,氮磷对黄土丘陵区退耕草地优势种光合生理具有一定的交互作用,物种属性和施肥水平影响其光合生理特征响应程度。展开更多
基金funded by the National Natural Science Foundation of China (41030535, 41371069)the Fundamental Research Funds for the Central Universitiesthe Program for Changjiang Scholars and Innovative Research Team in University (IRT1108)
文摘Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass（AGB）, biodiversity and community stability associated with different management practices were studied with a three-year field investigation in a temperate steppe of Inner Mongolia, China. The species richness, Shannon-Wiener index, evenness, plant functional type abundance, AGB, temporal community stability, summed covariance, scaling coefficient and dominant species stability were compared among areas subjected to long-term reservation（R）, long-term grazing（G）, mowing since enclosure in 2008（M） and grazing enclosure since 2008（E）. Site R had higher perennial grass abundance and lower species richness than sites G, M and E, although the AGB was not significantly different among the four sites. The species structure varied from a single dominant species at site R to multiple dominant species at sites G, M and E. The long-term reservation grassland had lower biodiversity but higher stability, whereas the enclosed grassland with/without mowing had higher biodiversity but lower stability. Different stability mechanisms, such as the compensatory dynamics, mean-variance scaling and dominant species stability were examined. Results showed that community stability was most closely related to the relative stability of the dominant species, which supports the biomass ratio hypothesis proposed by Grime.
基金The Earmarked Fund for China Agriculture Research SystemScientific Research Foundation of Hainan Tropical Ocean University
文摘In order to test whether density dependence influences community diversity, a combination of manipulative experimentation and plot surveys were done using Cryptocarya concinna, a dominant species in subtropical evergreen forest. Twelve pairs of 1 m^2 seedling plots were built around 12 adults, and plots were treated monthly with either a fungicide or a control. The surviving proportion of C. concinna seedlings at different stages was calculated, and an analysis was conducted on the impact of fungicide on seedling survival and species richness. Correlation between relative abundance and community evenness at different ages was analyzed using plot surveys. The results showed that fungicide treatment decreased species richness of the seedling community by pro- moting the recruitment of common species. Furthermore, census of a 25 m radius around adult C. concinna trees confirmed that the density of saplings increased with distance from adults. Relative abundance of C. concinna decreased with increasing age, and decreasing C. concinna dominance resulted in an increase in community even- ness. To avoid the appearance of a single optimum population, the dominance of C. concinna decreased with age via density dependence, and subsequently improved community species diversity.
文摘以黄土丘陵区退耕草地群落典型优势种白羊草、长芒草和达乌里胡枝子为研究对象,测定不同氮磷(主区N:0,50,100 kg N hm^(-2)a^(-1);副区P:0,40,80 kg P_(2)O_(5) hm^(-2)a^(-1))添加处理下叶片光合气体交换参数、叶绿素荧光参数、叶片氮磷含量、光合氮利用效率(PNUE)和光合磷利用效率(PPUE),探究不同优势种光合生理特征对外源氮磷添加的响应特征与物种差异。结果表明:单独氮添加下,3个优势种的净光合速率(P_(n))、蒸腾速率、水分利用效率(WUE_(i))、气孔限制值(Ls)和光系统Ⅱ(PSⅡ)活性高于或显著高于未施肥处理,白羊草和达乌里胡枝子的PNUE和PPUE以及长芒草的PPUE显著增加。单独磷添加下,仅达乌里胡枝子的P_(n)、WUE_(i)、Ls和PNUE相比未施肥处理显著增加。氮磷共同添加下,50 kg N hm^(-2)a^(-1)处理下,施磷后达乌里胡枝子的P_(n)以及三个优势种的PNUE显著增加,白羊草的PPUE显著降低;100 kg N hm^(-2)a^(-1)处理下,施磷后达乌里胡枝子的P_(n)和PNUE均显著增加,白羊草PPUE和长芒草的PNUE的仅在40 kg P_(2)O_(5) hm^(-2)a^(-1)处理下显著增加。3个优势种的P_(n)均与PSⅡ最大光化学效率和叶片氮含量呈显著正相关关系,长芒草和达乌里胡枝子的P_(n)与PSⅡ潜在活性和叶片磷含量呈显著正相关关系。总体表明,氮磷对黄土丘陵区退耕草地优势种光合生理具有一定的交互作用,物种属性和施肥水平影响其光合生理特征响应程度。
