Background:Soil acidifcationn caused by anthropogenic activities may aft soil biochemical cydling,bidiversity,productivity,and multiple eosystem-related functions in drylands.However,to date,such information is lackin...Background:Soil acidifcationn caused by anthropogenic activities may aft soil biochemical cydling,bidiversity,productivity,and multiple eosystem-related functions in drylands.However,to date,such information is lacking to support this hypothesis.Methods Based on a transect survey of 78 naturally assembled shrub communities,we caloulated acid deposition flux in Northwest China and evaluated its likely ecological ffets by testing three altemnative hypotheses,namely:.nidche complementarity,mass ratio,and vegetation quantity hypotheses Rao's quadratic entopy and community-weighted mean traits were employed to represent the complementary aspect of niche complementarity and mass ratio effects,respectively.Resulbs:We observed that in the past four decades,the concentrations of exchangeable base cations in soil in Northwest China have decreased significantly to the extent of having faced the risk of depletion,whereas changes in the calium carbonate content and pH of soil were not significant.Adid deposition primani ly increased the aboweground biomass and shrub density in shrublands but had no sigmificant effect on shrub richness and ecasystem multifunctionality(EMF),indicating that acid deposition had positive but weak ecological effects on dryland ecosystems.Community wd ghted mean of functional traits(representing the mass ratio hypothesis)correlated negatively with EMF,whereas both Rao's quadratic entropy(representing the niche complementarity hypothesis)and aboveground biomass(representing the vegetation quantity hypothesis)correlated positively but insignifcantly with EMF.These biodiversity-EMF relationships highlight the fragility and instability of drylands relative to forest ecasystems.Concuions:The findings from this study serve as important reference points to understand the ris of soil acidification in arid regions and its impacts on biodiversity-EMF relationships.展开更多
Water and nitrogen （N） inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influen...Water and nitrogen （N） inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influencing biodiversity and ecosystem function.Snowfall is a form of precipitation in winter,and snow melting can recharge soil water and result in a flourish of ephemerals during springtime in the Gurbantunggut Desert,China.A bi-factor experiment was designed and deployed during the snow-covering season from 2009 to 2010.The experiment aimed to explore the effects of different snow-covering depths and N addition levels on ephemerals.Findings indicated that deeper snow cover led to the increases in water content in topsoil as well as density and coverage of ephemeral plants in the same N treatment; by contrast,N addition sharply decreased the density of ephemerals in the same snow treatment.Meanwhile,N addition exhibited a different effect on the growth of ephemeral plants：in the 50％ snow treatment,N addition limited the growth of ephemeral plants,showing that the height and the aboveground biomass of the ephemeral plants were lower than in those without N addition; while with the increases in snow depth （100％ and 150％ snow treatments）,N addition benefited the growth of the dominant individual plants.Species richness was not significantly affected by snow in the same N treatment.However,N addition significantly decreased the species richness in the same snow-covering depth.The primary productivity of ephemerals in the N addition increased with the increase of snow depth.These variations indicated that the effect of N on the growth of ephemerals was restricted by water supply.With plenty of water （100％ and 150％ snow treatments）,N addition contributed to the growth of ephemeral plants; while with less water （50％ snow treatment）,N addition restricted the growth of ephemeral plants.展开更多
Determining the mechanisms underlying the spatial distribution of plant species is one of the central themes in biogeography and ecology. However, we are still far from gaining a full understanding of the autecologica...Determining the mechanisms underlying the spatial distribution of plant species is one of the central themes in biogeography and ecology. However, we are still far from gaining a full understanding of the autecological processes needed to unravel species distribution patterns. In the current study, by comparing seedling recruitment, seedling morphological performance and biomass allocation of two Haloxylon species, we try to identify the causes of the dune/interdune distribution pattern of these two species. Our results show the soil on the dune had less nutrients but was less saline than that of the interdune; with prolonged summer drought, soil water availability was lower on the dune than on the interdune. Both species had higher densities of seedlings at every stage of recruitment in their native habitat than the adjacent habitat. The contrasting different adaptation to nutrients, salinity and soil water conditions in the seedling recruitment stage strongly determined the distribution patterns of the two species on the dune/interdune. Haloxylon persicum on the dunes had lower total dry biomass, shoot and root dry biomass, but allocated a higher percentage of its biomass to roots and possessed a higher specific root length and specific root area by phenotypic traits specialization than that of Haloxylon ammodendron on the interdune. All of these allowed H. persicum to be more adapted to water stress and nutrient shortage. The differences in morphology and allocation facilitated the ability of these two species to persist in their own environments.展开更多
基金financially supported by the third xinjiang scientific expedition program (grant no.2022xjkk0901)the Strategic Priority Research Program of Chinese Academy of Sciences (No.XDA2006030102)the National Natural Sciences Foundation of China(No.42171068 and No.42330503)。
文摘Background:Soil acidifcationn caused by anthropogenic activities may aft soil biochemical cydling,bidiversity,productivity,and multiple eosystem-related functions in drylands.However,to date,such information is lacking to support this hypothesis.Methods Based on a transect survey of 78 naturally assembled shrub communities,we caloulated acid deposition flux in Northwest China and evaluated its likely ecological ffets by testing three altemnative hypotheses,namely:.nidche complementarity,mass ratio,and vegetation quantity hypotheses Rao's quadratic entopy and community-weighted mean traits were employed to represent the complementary aspect of niche complementarity and mass ratio effects,respectively.Resulbs:We observed that in the past four decades,the concentrations of exchangeable base cations in soil in Northwest China have decreased significantly to the extent of having faced the risk of depletion,whereas changes in the calium carbonate content and pH of soil were not significant.Adid deposition primani ly increased the aboweground biomass and shrub density in shrublands but had no sigmificant effect on shrub richness and ecasystem multifunctionality(EMF),indicating that acid deposition had positive but weak ecological effects on dryland ecosystems.Community wd ghted mean of functional traits(representing the mass ratio hypothesis)correlated negatively with EMF,whereas both Rao's quadratic entropy(representing the niche complementarity hypothesis)and aboveground biomass(representing the vegetation quantity hypothesis)correlated positively but insignifcantly with EMF.These biodiversity-EMF relationships highlight the fragility and instability of drylands relative to forest ecasystems.Concuions:The findings from this study serve as important reference points to understand the ris of soil acidification in arid regions and its impacts on biodiversity-EMF relationships.
基金funded by the National Basic Research Program of China(2009CB825102)the National Basic Research Program of China(2009CB421102E)+1 种基金the International Science & Technology Cooperation Program of China(2010DFA92720)the Natural Science Foundation of China(4117049)
文摘Water and nitrogen （N） inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influencing biodiversity and ecosystem function.Snowfall is a form of precipitation in winter,and snow melting can recharge soil water and result in a flourish of ephemerals during springtime in the Gurbantunggut Desert,China.A bi-factor experiment was designed and deployed during the snow-covering season from 2009 to 2010.The experiment aimed to explore the effects of different snow-covering depths and N addition levels on ephemerals.Findings indicated that deeper snow cover led to the increases in water content in topsoil as well as density and coverage of ephemeral plants in the same N treatment; by contrast,N addition sharply decreased the density of ephemerals in the same snow treatment.Meanwhile,N addition exhibited a different effect on the growth of ephemeral plants：in the 50％ snow treatment,N addition limited the growth of ephemeral plants,showing that the height and the aboveground biomass of the ephemeral plants were lower than in those without N addition; while with the increases in snow depth （100％ and 150％ snow treatments）,N addition benefited the growth of the dominant individual plants.Species richness was not significantly affected by snow in the same N treatment.However,N addition significantly decreased the species richness in the same snow-covering depth.The primary productivity of ephemerals in the N addition increased with the increase of snow depth.These variations indicated that the effect of N on the growth of ephemerals was restricted by water supply.With plenty of water （100％ and 150％ snow treatments）,N addition contributed to the growth of ephemeral plants; while with less water （50％ snow treatment）,N addition restricted the growth of ephemeral plants.
基金supported by the Western Light Program of the Chinese Academy of Sciences (XBBS201001)the National Natural Science Foundation of China (40971042, 41371079)the International Science & Technology Cooperation Program of China (2010DFA92720)
文摘Determining the mechanisms underlying the spatial distribution of plant species is one of the central themes in biogeography and ecology. However, we are still far from gaining a full understanding of the autecological processes needed to unravel species distribution patterns. In the current study, by comparing seedling recruitment, seedling morphological performance and biomass allocation of two Haloxylon species, we try to identify the causes of the dune/interdune distribution pattern of these two species. Our results show the soil on the dune had less nutrients but was less saline than that of the interdune; with prolonged summer drought, soil water availability was lower on the dune than on the interdune. Both species had higher densities of seedlings at every stage of recruitment in their native habitat than the adjacent habitat. The contrasting different adaptation to nutrients, salinity and soil water conditions in the seedling recruitment stage strongly determined the distribution patterns of the two species on the dune/interdune. Haloxylon persicum on the dunes had lower total dry biomass, shoot and root dry biomass, but allocated a higher percentage of its biomass to roots and possessed a higher specific root length and specific root area by phenotypic traits specialization than that of Haloxylon ammodendron on the interdune. All of these allowed H. persicum to be more adapted to water stress and nutrient shortage. The differences in morphology and allocation facilitated the ability of these two species to persist in their own environments.
