Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity.Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patter...Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity.Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patterns.Five southern islands in the Miaodao Archipelago,North China were studied herein.The spatial distribution of herbaceous plant diversity on these islands was analyzed,and the impact factors and their degree of impact on spatial heterogeneity were identified using CCA ordination and ANOVA.The results reveal 114 herbaceous plant species,belonging to 94 genera from 34 families in the50 plots sampled.The total species numbers on different islands were significantly positively correlated with island area,and the average a diversity was correlated with human activities,while the(3 diversity among islands was more affected by island area than mutual distances.Spatial heterogeneity within islands indicated that the diversities were generally high in areas with higher altitude,slope,total nitrogen,total carbon,and canopy density,and lower moisture content,pH,total phosphorus,total potassium,and aspect.Among the environmental factors,pH,canopy density,total K,total P,moisture content,altitude,and slope had significant gross effects,but only canopy density exhibited a significant net effect.Terrain affected diversity by restricting plantation,plantation in turn influenced soil properties and the two together affected diversity.Therefore,plantation was ultimately the fundamental driving factor for spatial heterogeneity in herbaceous plant diversity on the five islands.展开更多
Exotic plant invasion is a growing concern in the conservation and management of indigenous arid land ecosystems. By creating areas of ameliorated microclimates and fertile soil below their canopies, perennial plants ...Exotic plant invasion is a growing concern in the conservation and management of indigenous arid land ecosystems. By creating areas of ameliorated microclimates and fertile soil below their canopies, perennial plants might influence exotic annual plant invasions. We conducted a quantitative literature review of studies that compared exotic annual plant abundance among native perennial plant species and interspace （open areas） microsites in North America＇s Mojave Desert, where exotic plant invasion has corresponded with increasing extent of wildfire and broad-scale ecosystem transformation. Ten studies compared exotic annual plant abundance between inter- spaces and below a total of 36 native perennial species. These studies revealed that： （1） With few exceptions, most native perennial species supported a greater abundance of exotic annuals than interspaces, indicating overall facilitation of exotic species by native perennials. （2） Exotic species abundance varied by orders of magnitude among native perennial species, with some perennial species harboring amounts of exotics similar to interspaces. （3） Distributions of dominant exotic species varied, where Bromus rubens displayed a greater affinity for below-perennial microsites than did Schismus spp. and Erodium cicutarium that often were most abundant in interspaces. Results suggest that the degree of facilitation of exotic plants warrants consideration when selecting native perennial species for revegetation and restoration projects.展开更多
Brinjal or eggplant (Solanum melongena L.) is severely affected by bacterial wilt caused by Ralstonia solanecearum in Andaman and Nicobar Islands. Resistant varieties are most suitable option to reduce crop losses fro...Brinjal or eggplant (Solanum melongena L.) is severely affected by bacterial wilt caused by Ralstonia solanecearum in Andaman and Nicobar Islands. Resistant varieties are most suitable option to reduce crop losses from bacterial wilt but knowledge of resistance mechanism and its inheritance is important to develop resistant varieties. Further, majority of germplasm from mainland India showed susceptible reaction under Andaman conditions. Thus, the present study was done during 2010-2012 to understand the genetic behaviour of bacterial wilt resistance in brinjal “CARI-B-1” (R) × “Pusa Purple Long” (S) in hot humid tropical climate of Andaman Islands. For this, the population from single F<sub>1</sub> fruit was advanced to F<sub>2</sub> and F<sub>3</sub> and recorded the reaction of segregating population in the sick plots. The results revealed that there is preponderance of recessive gene family wherein more than one gene acts in additive mode. Another cross between S. torvum (R) × Diglipur local collection (S) also showed the recessive gene action for resistance as observed in F<sub>2</sub> generation. Besides, the study also advocated that mechanisms of resistance, escape with early resistance and progressive escape have been found to be operating in individuals of segregating population.展开更多
The relationship between species richness and elevation is a hot issue in ecology and has been documented extensively.It is widely accepted that area size can significantly affect this relationship and thus mask the e...The relationship between species richness and elevation is a hot issue in ecology and has been documented extensively.It is widely accepted that area size can significantly affect this relationship and thus mask the effects of other predictors.Despite the importance of the relationship between species richness and elevation while accounting for the area effect,it is insufficiently studied.Here,we evaluated area-corrected species richness patterns of all vascular plants as well as six vascular plant subgroups(seed plants,ferns,trees,shrubs,herbsand vines)along a tropical elevational gradient(Hainan Island,China).If assessed in equal-elevation bands,uncorrected species richness showed bell-shaped curves,while area-corrected species richness assessed in equal-area bands appeared to increase monotonically due to the small proportion of highlands on Hainan Island.The mid-domain effect(MDE) was significantly correlated with both uncorrected and area-corrected species richness.On Hainan Island,the use of equal-area elevational bands increased the explanatory power of MDE.These findings provide useful insights to adjust for the area effect and highlight the need to use equalarea bands along the elevational gradient.展开更多
由于无法辨析并网点(point of common coupling,PCC)电压跌落的本质原因,光伏电站低压穿越(low voltage ride through,LVRT)控制与现有的孤岛保护在同时满足动作条件时缺乏选择性,影响系统的安全稳定。为研究与光伏LVRT相互协调的孤岛...由于无法辨析并网点(point of common coupling,PCC)电压跌落的本质原因,光伏电站低压穿越(low voltage ride through,LVRT)控制与现有的孤岛保护在同时满足动作条件时缺乏选择性,影响系统的安全稳定。为研究与光伏LVRT相互协调的孤岛检测方法,根据孤岛现象和电压暂态扰动现象发生时PCC谐波电压的差异,提出一种基于光伏并网点谐波电压突变的无功功率扰动孤岛检测方法。该方法在检测到PCC处的谐波电压突变后,经40 ms延时,对光伏逆变器输出的无功电流采用基于PCC频率变化量函数进行扰动,使PCC频率超出正常范围,实现孤岛检测功能。仿真结果表明:方法在保证与LVRT协调配合的前提下能在较短时间内完成对光伏电站孤岛状态的检测;此外在故障特征量较小的工况下方法依然可靠适用,消除了传统孤岛检测方法盲区的同时保证了孤岛检测的准确性。展开更多
基金Supported by the National Special Fund for Basic Science and Technology of China(No.2012FY112500)the Public Science and Technology Research Funds Projects of Ocean in China(Nos.201305009,201505012)the Special Fund of Chinese Central Government for Basic Scientific Research Operations in Commonweal Research Institutes(No.FIO2015G13)
文摘Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity.Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patterns.Five southern islands in the Miaodao Archipelago,North China were studied herein.The spatial distribution of herbaceous plant diversity on these islands was analyzed,and the impact factors and their degree of impact on spatial heterogeneity were identified using CCA ordination and ANOVA.The results reveal 114 herbaceous plant species,belonging to 94 genera from 34 families in the50 plots sampled.The total species numbers on different islands were significantly positively correlated with island area,and the average a diversity was correlated with human activities,while the(3 diversity among islands was more affected by island area than mutual distances.Spatial heterogeneity within islands indicated that the diversities were generally high in areas with higher altitude,slope,total nitrogen,total carbon,and canopy density,and lower moisture content,pH,total phosphorus,total potassium,and aspect.Among the environmental factors,pH,canopy density,total K,total P,moisture content,altitude,and slope had significant gross effects,but only canopy density exhibited a significant net effect.Terrain affected diversity by restricting plantation,plantation in turn influenced soil properties and the two together affected diversity.Therefore,plantation was ultimately the fundamental driving factor for spatial heterogeneity in herbaceous plant diversity on the five islands.
基金facilitated by funding provided by cooperative agreements between the National Park Service (Lake Mead National Recreation Area,in particular Alice NEWTON) and the University of Nevada Las Vegas (UNLV)
文摘Exotic plant invasion is a growing concern in the conservation and management of indigenous arid land ecosystems. By creating areas of ameliorated microclimates and fertile soil below their canopies, perennial plants might influence exotic annual plant invasions. We conducted a quantitative literature review of studies that compared exotic annual plant abundance among native perennial plant species and interspace （open areas） microsites in North America＇s Mojave Desert, where exotic plant invasion has corresponded with increasing extent of wildfire and broad-scale ecosystem transformation. Ten studies compared exotic annual plant abundance between inter- spaces and below a total of 36 native perennial species. These studies revealed that： （1） With few exceptions, most native perennial species supported a greater abundance of exotic annuals than interspaces, indicating overall facilitation of exotic species by native perennials. （2） Exotic species abundance varied by orders of magnitude among native perennial species, with some perennial species harboring amounts of exotics similar to interspaces. （3） Distributions of dominant exotic species varied, where Bromus rubens displayed a greater affinity for below-perennial microsites than did Schismus spp. and Erodium cicutarium that often were most abundant in interspaces. Results suggest that the degree of facilitation of exotic plants warrants consideration when selecting native perennial species for revegetation and restoration projects.
文摘Brinjal or eggplant (Solanum melongena L.) is severely affected by bacterial wilt caused by Ralstonia solanecearum in Andaman and Nicobar Islands. Resistant varieties are most suitable option to reduce crop losses from bacterial wilt but knowledge of resistance mechanism and its inheritance is important to develop resistant varieties. Further, majority of germplasm from mainland India showed susceptible reaction under Andaman conditions. Thus, the present study was done during 2010-2012 to understand the genetic behaviour of bacterial wilt resistance in brinjal “CARI-B-1” (R) × “Pusa Purple Long” (S) in hot humid tropical climate of Andaman Islands. For this, the population from single F<sub>1</sub> fruit was advanced to F<sub>2</sub> and F<sub>3</sub> and recorded the reaction of segregating population in the sick plots. The results revealed that there is preponderance of recessive gene family wherein more than one gene acts in additive mode. Another cross between S. torvum (R) × Diglipur local collection (S) also showed the recessive gene action for resistance as observed in F<sub>2</sub> generation. Besides, the study also advocated that mechanisms of resistance, escape with early resistance and progressive escape have been found to be operating in individuals of segregating population.
基金the support provided by the National Special Water Programs (Grant Nos. 2009ZX07210-009, 2015ZX07203-011, 2015ZX07204-007)the Department of Environmental Protection of Shandong Province (SDHBPJ-ZB-08)+2 种基金the ChinaScholarship Council (Grant No. 201306730020)the Chinese Natural Science Foundation (Grant No. 39560023)Queen Mary University of London
文摘The relationship between species richness and elevation is a hot issue in ecology and has been documented extensively.It is widely accepted that area size can significantly affect this relationship and thus mask the effects of other predictors.Despite the importance of the relationship between species richness and elevation while accounting for the area effect,it is insufficiently studied.Here,we evaluated area-corrected species richness patterns of all vascular plants as well as six vascular plant subgroups(seed plants,ferns,trees,shrubs,herbsand vines)along a tropical elevational gradient(Hainan Island,China).If assessed in equal-elevation bands,uncorrected species richness showed bell-shaped curves,while area-corrected species richness assessed in equal-area bands appeared to increase monotonically due to the small proportion of highlands on Hainan Island.The mid-domain effect(MDE) was significantly correlated with both uncorrected and area-corrected species richness.On Hainan Island,the use of equal-area elevational bands increased the explanatory power of MDE.These findings provide useful insights to adjust for the area effect and highlight the need to use equalarea bands along the elevational gradient.
文摘由于无法辨析并网点(point of common coupling,PCC)电压跌落的本质原因,光伏电站低压穿越(low voltage ride through,LVRT)控制与现有的孤岛保护在同时满足动作条件时缺乏选择性,影响系统的安全稳定。为研究与光伏LVRT相互协调的孤岛检测方法,根据孤岛现象和电压暂态扰动现象发生时PCC谐波电压的差异,提出一种基于光伏并网点谐波电压突变的无功功率扰动孤岛检测方法。该方法在检测到PCC处的谐波电压突变后,经40 ms延时,对光伏逆变器输出的无功电流采用基于PCC频率变化量函数进行扰动,使PCC频率超出正常范围,实现孤岛检测功能。仿真结果表明:方法在保证与LVRT协调配合的前提下能在较短时间内完成对光伏电站孤岛状态的检测;此外在故障特征量较小的工况下方法依然可靠适用,消除了传统孤岛检测方法盲区的同时保证了孤岛检测的准确性。
