As global warming persistently alters and rapidly reshapes landscapes and habitats, conventional species distribution models relying solely on maintaining static conditions within the current climate are likely to fal...As global warming persistently alters and rapidly reshapes landscapes and habitats, conventional species distribution models relying solely on maintaining static conditions within the current climate are likely to falter, particularly at the genus level. Hence, we hypothesize that climate change will differentially affect ecological niches of the same genus species with various latitudinal positioning and local topography, and the high-latitude species may experience greater niche contraction than low-latitude species, and that mountainous regions with high elevational variability may serve as critical climate refugia. Herein, we simulate niche alterations and integrate an ensemble model(EM) strategy, taking into account species dispersal limitations factors(topography, soil, and ultraviolet), to construct a comprehensive habitat suitability(CHS) model for assessing the future vulnerability of the Betula genus, most of which are timber species in China. Our findings reveal that the niche spatial(geographic distribution) of most species(62%) within the Betula genus will undergo a gradual decline under climate change, supporting our hypothesis of latitudinal differentiation in climate vulnerability. Intriguingly, the projected high-latitude niche reduction within the genus cannot be counterbalanced by the anticipated niche expansion of closely related species in low-latitude regions, even considering the evident latitudinal gradient distribution of species. Nonetheless, the niche spatial of six Betula species in southwestern China remains stable or expands under warming scenarios, strongly supporting our secondary hypothesis about topographic buffering effects, which probably means the unique topography(i.e., the largest elevation difference) of this region may serve as a sanctuary for preserving Betula genetic diversity. Our results underscore the uncertain nature of pre-existing niche systems at the genus level under climate change, emphasizing the need for diligent resource management and conservation planning for vulnerable timber species.展开更多
The population dynamics and breeding behaviors of Black-crowned Night Herons （ Nycticorax nycticorax ）, Egrets （Egtetta garzetta）, Chinese Pond Herons （Ardeola bacchus） and Great Egrets （Casmerodius albus） wer...The population dynamics and breeding behaviors of Black-crowned Night Herons （ Nycticorax nycticorax ）, Egrets （Egtetta garzetta）, Chinese Pond Herons （Ardeola bacchus） and Great Egrets （Casmerodius albus） were observed in Tanghai Wetlands, Hebei Province from August 2004 to July 2005. Further, we studied the relationship of nest space distribution and directly calculated the nest density of vertical and horizontal levels, the niche overlapping index and the niche breadth. The results showed that there were two breeding areas, named Area Ⅰ and Area Ⅱ . The maximum population occurred in the period from April to September and was approximately 5800 individuals. Area Ⅰ was occupied earlier than Area Ⅱ by approximately half a month. In the breeding period, Black-crowned Night Herons were dominant in numbers and most occupied the upper nests of the core areas. Great Egrets also took the upper nests but they have the smallest population. Most Egrets took the middle nests of the edges of the area. Chinese Pond Herons, with a smaller population than the Egret, mostly nested in the edges, but some of them also took the lower nests of the core area. On the whole, the vertical niche of Egrets is the widest, the horizontal niche of Black-crowned Night Herons is the widest and the niche breadth of Chinese Pond Herons is the largest. The nest distribution pattern is the most similar between Chinese Pond Herons and Black-crowned Night Herons, and the niche overlapping index of Chinese Pond Herons and Egrets is the largest. Black-crowned Night Herons and Great Egrets control Egrets and Chinese Pond Herons in competition. Rich food and the optimal ecological environments lead to plenty of herons in the wetlands. In addition, it is a distinguishing feature of the four species that nests are built in poplar trees over 22 m tall.展开更多
Aims Aboveground biomass production commonly increases with species richness in plant biodiversity experiments.Little is known about the direct mechanisms that cause this result.We tested if by occupying different hei...Aims Aboveground biomass production commonly increases with species richness in plant biodiversity experiments.Little is known about the direct mechanisms that cause this result.We tested if by occupying different heights and depths above and below ground,and by optimizing the vertical distribution of leaf nitrogen,species in mixtures can contribute to increased resource uptake and,thus,increased productivity of the community in comparison with monocultures.Methods We grew 24 grassland plant species,grouped into four nonoverlapping species pools,in monoculture and 3-and 6-species mixture in spatially heterogeneous and uniform soil nutrient conditions.Layered harvests of above-and belowground biomass,as well as leaf nitrogen and light measurements,were taken to assess vertical canopy and root space structure.Important Findings The distribution of leaf mass was shifted toward greater heights and light absorption was correspondingly enhanced in mixtures.How ever,only some mixtures had leaf nitrogen concentration profiles predicted to optimize whole-community carbon gain,whereas in other mixtures species seemed to behave more‘selfish’.Nevertheless,even in these communities,biomass production increased with species richness.The distribution of root biomass below ground did not change from monocultures to three-and six-species mixtures and there was also no indication that mixtures were better than monocultures at extracting heterogeneously as compared to homogeneously distributed soil resources.We conclude that positive biodiversity effect on aboveground biomass production cannot easily be explained by a single or few common mechanisms of differential space use.Rather,it seems that mechanisms vary with the particular set of species combined in a community.展开更多
基金funded by the National Science Foundation for Young Scientists of China(No.32001327)the National Key Research and Development Program of China(No.2021YFD2200304-2).
文摘As global warming persistently alters and rapidly reshapes landscapes and habitats, conventional species distribution models relying solely on maintaining static conditions within the current climate are likely to falter, particularly at the genus level. Hence, we hypothesize that climate change will differentially affect ecological niches of the same genus species with various latitudinal positioning and local topography, and the high-latitude species may experience greater niche contraction than low-latitude species, and that mountainous regions with high elevational variability may serve as critical climate refugia. Herein, we simulate niche alterations and integrate an ensemble model(EM) strategy, taking into account species dispersal limitations factors(topography, soil, and ultraviolet), to construct a comprehensive habitat suitability(CHS) model for assessing the future vulnerability of the Betula genus, most of which are timber species in China. Our findings reveal that the niche spatial(geographic distribution) of most species(62%) within the Betula genus will undergo a gradual decline under climate change, supporting our hypothesis of latitudinal differentiation in climate vulnerability. Intriguingly, the projected high-latitude niche reduction within the genus cannot be counterbalanced by the anticipated niche expansion of closely related species in low-latitude regions, even considering the evident latitudinal gradient distribution of species. Nonetheless, the niche spatial of six Betula species in southwestern China remains stable or expands under warming scenarios, strongly supporting our secondary hypothesis about topographic buffering effects, which probably means the unique topography(i.e., the largest elevation difference) of this region may serve as a sanctuary for preserving Betula genetic diversity. Our results underscore the uncertain nature of pre-existing niche systems at the genus level under climate change, emphasizing the need for diligent resource management and conservation planning for vulnerable timber species.
文摘The population dynamics and breeding behaviors of Black-crowned Night Herons （ Nycticorax nycticorax ）, Egrets （Egtetta garzetta）, Chinese Pond Herons （Ardeola bacchus） and Great Egrets （Casmerodius albus） were observed in Tanghai Wetlands, Hebei Province from August 2004 to July 2005. Further, we studied the relationship of nest space distribution and directly calculated the nest density of vertical and horizontal levels, the niche overlapping index and the niche breadth. The results showed that there were two breeding areas, named Area Ⅰ and Area Ⅱ . The maximum population occurred in the period from April to September and was approximately 5800 individuals. Area Ⅰ was occupied earlier than Area Ⅱ by approximately half a month. In the breeding period, Black-crowned Night Herons were dominant in numbers and most occupied the upper nests of the core areas. Great Egrets also took the upper nests but they have the smallest population. Most Egrets took the middle nests of the edges of the area. Chinese Pond Herons, with a smaller population than the Egret, mostly nested in the edges, but some of them also took the lower nests of the core area. On the whole, the vertical niche of Egrets is the widest, the horizontal niche of Black-crowned Night Herons is the widest and the niche breadth of Chinese Pond Herons is the largest. The nest distribution pattern is the most similar between Chinese Pond Herons and Black-crowned Night Herons, and the niche overlapping index of Chinese Pond Herons and Egrets is the largest. Black-crowned Night Herons and Great Egrets control Egrets and Chinese Pond Herons in competition. Rich food and the optimal ecological environments lead to plenty of herons in the wetlands. In addition, it is a distinguishing feature of the four species that nests are built in poplar trees over 22 m tall.
基金Swiss National Science Foundation(31-65224-01 to B.S.).
文摘Aims Aboveground biomass production commonly increases with species richness in plant biodiversity experiments.Little is known about the direct mechanisms that cause this result.We tested if by occupying different heights and depths above and below ground,and by optimizing the vertical distribution of leaf nitrogen,species in mixtures can contribute to increased resource uptake and,thus,increased productivity of the community in comparison with monocultures.Methods We grew 24 grassland plant species,grouped into four nonoverlapping species pools,in monoculture and 3-and 6-species mixture in spatially heterogeneous and uniform soil nutrient conditions.Layered harvests of above-and belowground biomass,as well as leaf nitrogen and light measurements,were taken to assess vertical canopy and root space structure.Important Findings The distribution of leaf mass was shifted toward greater heights and light absorption was correspondingly enhanced in mixtures.How ever,only some mixtures had leaf nitrogen concentration profiles predicted to optimize whole-community carbon gain,whereas in other mixtures species seemed to behave more‘selfish’.Nevertheless,even in these communities,biomass production increased with species richness.The distribution of root biomass below ground did not change from monocultures to three-and six-species mixtures and there was also no indication that mixtures were better than monocultures at extracting heterogeneously as compared to homogeneously distributed soil resources.We conclude that positive biodiversity effect on aboveground biomass production cannot easily be explained by a single or few common mechanisms of differential space use.Rather,it seems that mechanisms vary with the particular set of species combined in a community.
