Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low na...Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low native diversity' vs. ‘high native diversity', is supported by the regional distribution patterns of invasive plant species in the Himalayas,Nepal. This study is based on data retrieved from published literatures and herbarium specimens. The relationship between invasive plant species distribution patterns and that of native plant species is elucidated by scatter plots, as well as by generalized linear models. The native plant species and invasive plant species have similar distribution patterns and the maximum number of invasive plant species is found in the same altitudinal range where the highest richness for native tree species is found. There is a clear trend of higher invasive plant richness in regions where native tree species richness is relatively high.Consequently, the native plant richness is highest in the central phytogeographic region, followed by the eastern and the western regions, respectively. The invasive plant species also follows a similar trend.Additionally, the invasive plant species richness was positively correlated with anthropogenic factors such as human population density and the number of visiting tourists. This study supports the hypothesis that ‘high native diversity' supports or facilitates invasive plant species. Further, it indicates that nativeand invasive plant species may require similar natural conditions, but that the invasive plant species seem more dependent and influenced by anthropogenic disturbance factors.展开更多
Oak gall wasps （Hymenoptera： Cynipidae）, with more than 1300 species, represent one of the largest radiations of gall inducing insects. Many studies have documented galling species lists and richness, especially ga...Oak gall wasps （Hymenoptera： Cynipidae）, with more than 1300 species, represent one of the largest radiations of gall inducing insects. Many studies have documented galling species lists and richness, especially gall wasps, but few studies have been directed toward understanding how the gall-inducing species are locally distributed. In this survey, the oak gall wasps were collected from April to November （2009 and 2010） in West Azerbaijan of Iran. Among these collected galls, five species of oak gall wasps which belonged to the genus Neuroterus sp. were identified as： Neuroterus lanuginosus Giraud, N. numismalis Geoffroy, N. saliens Kollar, N. laeviusculus Schenck and N. quercus-baccarum Linnaeus. All of the galls in this survey are leaf galls. These galls were produced by the asexual reproduction and were collected in summer and fall seasons. The highest species richness was recorded in Ghabre-hossein and Vavan stations. Also, the highest density of gall formation was recorded at the southern direction. The multiple-sites similarity measures indicated that similarity in gall composition and community between collecting sites was generally between 0.57 and 0.90. The highest multiple site similarity was recorded between Vavan vs Rabat vs Dare-ghabr station. The authors showed that the very cold and humidity climate is not appropriate to Neuroterus species activity and the south direction is the best side for their survival.展开更多
The present study aimed to investigate avian diversity in hedgerows at Angacha, in the Kembatta zone, Ethiopia. Transect and point-count methods were deployed to determine avian diversity, species richness, similarity...The present study aimed to investigate avian diversity in hedgerows at Angacha, in the Kembatta zone, Ethiopia. Transect and point-count methods were deployed to determine avian diversity, species richness, similarity and preferences across five sub study sites. Diversity and preferences of birds to hedgerow types varied in relation to their vegetation composition and structure. Five endemic species, i.e., Rüppel’s Black Chat (Cossyfa semirufa), the White-cheeked Turaco (Tauraco leucotis), the Banded Barbet (Lybius undatus), the Abyssinian Oriole (Oriolus monacha) and the Wattled Ibis (Bostrychia carucullatta) were recorded in the thick hedgerow type. Thickness, height and width of hedgerows affected the diversity, distribution and habitat preference of birds. Thick hedgerow types showed the highest avian species diversity, richness and similarity. There was a high correlation between the hedgerow diversity and its bird diversity, which was directly associated with habitat quality. Bird species diversity and preference for hedgerow types require important conservation and management priorities.展开更多
Coarse roots play a critical role in forest ecosystems and both abiotic and biotic factors affect their spatial distribution.To some extent,coarse root density may reflect the quantity of root biomass and biotic compe...Coarse roots play a critical role in forest ecosystems and both abiotic and biotic factors affect their spatial distribution.To some extent,coarse root density may reflect the quantity of root biomass and biotic competition in forests.However,using traditional methods(e.g.,excavation)to study coarse roots is challenging,because those methods are time-consuming and laborious.Furthermore,these destructive methods cannot be repeated in the same forests.Therefore,the discovery of non-destructive methods for root studies will be very significant.In this study,we used a ground-penetrating radar technique to detect the coarse root density of three habitats(ridge,slope and valley)and the dominant tree species(Castanopsis eyrei and Schima superba)in a subtropical forest.We found that(i)the mean of coarse root density for these three habitats was 88.04roots m–2,with roots being mainly distributed at depths of 0–40 cm.Coarse root densities were lower in deeper soils and in areas far from the trunk.(ii)Coarse root densities differed significantly among the three habitats studied here with slope habitat having the lowest coarse root density.Compared with S.superba,C.eyrei had more roots distributed in deeper soils.Furthermore,coarse roots with a diameter>3 cm occurred more frequently in the valleys,compared with root densities in ridge and slope habitats,and most coarse roots occurred at soil depths of 20–40 cm.(iii)The coarse root density correlated negatively with tree species richness at soil depths of 40–60 cm.The abundances of the dominant species,such as C.eyrei,Cyclobalanopsis glauca,Pinus massoniana,had significant impacts on coarse root density.(iv)The soil depth of 0–40 cm was the"basic distribution layer"for coarse roots since the majority of coarse roots were found in this soil layer with an average root density of 84.18 roots m–2,which had no significant linear relationships with topography,tree species richness,rarefied tree species richness and tree density.Significant relationships between coarse root density and these factors were found at the soil depth of40–60 cm,which was the"potential distribution layer"for coarse root distribution.展开更多
基金part of the research project ‘Legal frameworks for Conservation of Biodiversity and Ecosystem Services in the Himalayas (HIMALINES)’ funded by the Norwegian Research Council (190153/V10) Olaf Grolles Legat
文摘Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low native diversity' vs. ‘high native diversity', is supported by the regional distribution patterns of invasive plant species in the Himalayas,Nepal. This study is based on data retrieved from published literatures and herbarium specimens. The relationship between invasive plant species distribution patterns and that of native plant species is elucidated by scatter plots, as well as by generalized linear models. The native plant species and invasive plant species have similar distribution patterns and the maximum number of invasive plant species is found in the same altitudinal range where the highest richness for native tree species is found. There is a clear trend of higher invasive plant richness in regions where native tree species richness is relatively high.Consequently, the native plant richness is highest in the central phytogeographic region, followed by the eastern and the western regions, respectively. The invasive plant species also follows a similar trend.Additionally, the invasive plant species richness was positively correlated with anthropogenic factors such as human population density and the number of visiting tourists. This study supports the hypothesis that ‘high native diversity' supports or facilitates invasive plant species. Further, it indicates that nativeand invasive plant species may require similar natural conditions, but that the invasive plant species seem more dependent and influenced by anthropogenic disturbance factors.
文摘Oak gall wasps （Hymenoptera： Cynipidae）, with more than 1300 species, represent one of the largest radiations of gall inducing insects. Many studies have documented galling species lists and richness, especially gall wasps, but few studies have been directed toward understanding how the gall-inducing species are locally distributed. In this survey, the oak gall wasps were collected from April to November （2009 and 2010） in West Azerbaijan of Iran. Among these collected galls, five species of oak gall wasps which belonged to the genus Neuroterus sp. were identified as： Neuroterus lanuginosus Giraud, N. numismalis Geoffroy, N. saliens Kollar, N. laeviusculus Schenck and N. quercus-baccarum Linnaeus. All of the galls in this survey are leaf galls. These galls were produced by the asexual reproduction and were collected in summer and fall seasons. The highest species richness was recorded in Ghabre-hossein and Vavan stations. Also, the highest density of gall formation was recorded at the southern direction. The multiple-sites similarity measures indicated that similarity in gall composition and community between collecting sites was generally between 0.57 and 0.90. The highest multiple site similarity was recorded between Vavan vs Rabat vs Dare-ghabr station. The authors showed that the very cold and humidity climate is not appropriate to Neuroterus species activity and the south direction is the best side for their survival.
文摘The present study aimed to investigate avian diversity in hedgerows at Angacha, in the Kembatta zone, Ethiopia. Transect and point-count methods were deployed to determine avian diversity, species richness, similarity and preferences across five sub study sites. Diversity and preferences of birds to hedgerow types varied in relation to their vegetation composition and structure. Five endemic species, i.e., Rüppel’s Black Chat (Cossyfa semirufa), the White-cheeked Turaco (Tauraco leucotis), the Banded Barbet (Lybius undatus), the Abyssinian Oriole (Oriolus monacha) and the Wattled Ibis (Bostrychia carucullatta) were recorded in the thick hedgerow type. Thickness, height and width of hedgerows affected the diversity, distribution and habitat preference of birds. Thick hedgerow types showed the highest avian species diversity, richness and similarity. There was a high correlation between the hedgerow diversity and its bird diversity, which was directly associated with habitat quality. Bird species diversity and preference for hedgerow types require important conservation and management priorities.
基金supported by the National Natural Science Foundation of China(31170457,30710103907)
文摘Coarse roots play a critical role in forest ecosystems and both abiotic and biotic factors affect their spatial distribution.To some extent,coarse root density may reflect the quantity of root biomass and biotic competition in forests.However,using traditional methods(e.g.,excavation)to study coarse roots is challenging,because those methods are time-consuming and laborious.Furthermore,these destructive methods cannot be repeated in the same forests.Therefore,the discovery of non-destructive methods for root studies will be very significant.In this study,we used a ground-penetrating radar technique to detect the coarse root density of three habitats(ridge,slope and valley)and the dominant tree species(Castanopsis eyrei and Schima superba)in a subtropical forest.We found that(i)the mean of coarse root density for these three habitats was 88.04roots m–2,with roots being mainly distributed at depths of 0–40 cm.Coarse root densities were lower in deeper soils and in areas far from the trunk.(ii)Coarse root densities differed significantly among the three habitats studied here with slope habitat having the lowest coarse root density.Compared with S.superba,C.eyrei had more roots distributed in deeper soils.Furthermore,coarse roots with a diameter>3 cm occurred more frequently in the valleys,compared with root densities in ridge and slope habitats,and most coarse roots occurred at soil depths of 20–40 cm.(iii)The coarse root density correlated negatively with tree species richness at soil depths of 40–60 cm.The abundances of the dominant species,such as C.eyrei,Cyclobalanopsis glauca,Pinus massoniana,had significant impacts on coarse root density.(iv)The soil depth of 0–40 cm was the"basic distribution layer"for coarse roots since the majority of coarse roots were found in this soil layer with an average root density of 84.18 roots m–2,which had no significant linear relationships with topography,tree species richness,rarefied tree species richness and tree density.Significant relationships between coarse root density and these factors were found at the soil depth of40–60 cm,which was the"potential distribution layer"for coarse root distribution.
