杨柳科(Salicaceae)植物种类繁多,适应性强,用途广泛,在维持陆地生态系统结构功能、发展林业生产等方面具有重要意义。本文基于CNKI和WOS(Web of Science)数据库,采用可视化工具VOSviewer对国内外杨柳科植物研究的相关文献进行了计量分...杨柳科(Salicaceae)植物种类繁多,适应性强,用途广泛,在维持陆地生态系统结构功能、发展林业生产等方面具有重要意义。本文基于CNKI和WOS(Web of Science)数据库,采用可视化工具VOSviewer对国内外杨柳科植物研究的相关文献进行了计量分析。结果表明:国内外杨柳科植物研究呈现出阶段性发展的变化趋势,研究杨柳科植物的起源和进化,探讨其系统发育关系是该领域的研究前沿和热点,植物资源保护和系统分类学等相关研究是该领域的未来发展趋势。我国杨柳科植物研究近年来发展较为迅速,总体处于国际先进水平。展开更多
Trees growing in a semi-arid sandy environment are often exposed to drought conditions due to seasonal variations in precipitation, low soil water retention and deep groundwater level.However, adaptability and plastic...Trees growing in a semi-arid sandy environment are often exposed to drought conditions due to seasonal variations in precipitation, low soil water retention and deep groundwater level.However, adaptability and plasticity of individuals to the changing drought conditions greatly vary among tree species.In this study, we estimated water use(Ts) of Mongolian Scots pine(MSP;Pinus sylvestris var.mongolica Litv.) based on sap flux density measurements over four successive years(2013–2016) that exhibited significant fluctuations in precipitation in a semi-arid sandy environment of northern China.The results showed that fluctuations in daily Ts synchronously varied with dry-wet cycles of soil moisture over the study period.The daily ratio of water use to reference evapotranspiration(Ts/ET0) on sunny days in each year showed a negative linear relationship with the severity of drought in the upper soil layer(0–1 m;P<0.01).The decrease in Ts induced by erratic drought during the growing season recovered due to precipitation.However, this recovery ability failed under prolonged and severe droughts.The Ts/ET0 ratio significantly declined with the progressive reduction in the groundwater level(gw) over the study period(P<0.01).We concluded that the upper soil layer contributed the most to the Ts of MSP during the growing season.The severity and duration of droughts in this layer greatly reduced Ts.Nevertheless, gw determined whether the Ts could completely recover after the alleviation of long-term soil drought.These results provide practical information for optimizing MSP management to stop ongoing degradation in the semi-arid sandy environments.展开更多
文摘杨柳科(Salicaceae)植物种类繁多,适应性强,用途广泛,在维持陆地生态系统结构功能、发展林业生产等方面具有重要意义。本文基于CNKI和WOS(Web of Science)数据库,采用可视化工具VOSviewer对国内外杨柳科植物研究的相关文献进行了计量分析。结果表明:国内外杨柳科植物研究呈现出阶段性发展的变化趋势,研究杨柳科植物的起源和进化,探讨其系统发育关系是该领域的研究前沿和热点,植物资源保护和系统分类学等相关研究是该领域的未来发展趋势。我国杨柳科植物研究近年来发展较为迅速,总体处于国际先进水平。
基金supported by the Fundamental Research Funds for the Central Nonprofit Research Institution of Chinese Academy of Forestry (CAFYBB2014MA013)the National Natural Science Foundation of China (31570704)the Major State Basic Research Development Program of China (2013CB429901)
文摘Trees growing in a semi-arid sandy environment are often exposed to drought conditions due to seasonal variations in precipitation, low soil water retention and deep groundwater level.However, adaptability and plasticity of individuals to the changing drought conditions greatly vary among tree species.In this study, we estimated water use(Ts) of Mongolian Scots pine(MSP;Pinus sylvestris var.mongolica Litv.) based on sap flux density measurements over four successive years(2013–2016) that exhibited significant fluctuations in precipitation in a semi-arid sandy environment of northern China.The results showed that fluctuations in daily Ts synchronously varied with dry-wet cycles of soil moisture over the study period.The daily ratio of water use to reference evapotranspiration(Ts/ET0) on sunny days in each year showed a negative linear relationship with the severity of drought in the upper soil layer(0–1 m;P<0.01).The decrease in Ts induced by erratic drought during the growing season recovered due to precipitation.However, this recovery ability failed under prolonged and severe droughts.The Ts/ET0 ratio significantly declined with the progressive reduction in the groundwater level(gw) over the study period(P<0.01).We concluded that the upper soil layer contributed the most to the Ts of MSP during the growing season.The severity and duration of droughts in this layer greatly reduced Ts.Nevertheless, gw determined whether the Ts could completely recover after the alleviation of long-term soil drought.These results provide practical information for optimizing MSP management to stop ongoing degradation in the semi-arid sandy environments.
