Aims West Ordos Desert(WOD)in Inner Mongolia of China is charac-terized by unique geographical and ecological features to avoid the direct invasion of Quaternary Continental Glaciation,so it hosts many endangered reli...Aims West Ordos Desert(WOD)in Inner Mongolia of China is charac-terized by unique geographical and ecological features to avoid the direct invasion of Quaternary Continental Glaciation,so it hosts many endangered relic species such as Tetraena mongol-ica,Ammopiptanthus mongolicus and Potaninia mongolica from Tertiary.However,how these plants utilize available water sources remains unknown.The objective of this study was to investigate the water utilization strategies of selected rare and endangered plant species in WOD by comparing hydrogen isotope ratios between their xylem water and possible water sources following four rainfall events of varying-intensities.Methods We measured the hydrogen isotope ratios of xylem water from T.mongolica,A.mongolicus and P.mongolica and an accom-panying species Sarcozygium xanthoxylum and potential water sources(including precipitation and soil water in different soil layers from 0 to 150 cm)over 9 days following each of four varying-intensity rainfall events during the summer of 2012.And then calculated the percentage utilization of potential water sources by each species after each rainfall events using the linear mixing model.We also made the measurements of soil moisture and root biomass in favor of interpretation of plant water use strategies.Important Findings Tetraena mongolica,A.mongolicus and S.xanthoxylum primarily relied on deep soil water,whereas P.mongolica depended predomi-nantly on rainwater.These rare and endangered desert plants had differential utilizations of available water sources,so some com-petition for limited water existed among some species.Tetraena mongolica had a competitive relationship in absorption of soil moisture with the same family species S.xanthoxylum,suggesting that T.mongolica and S.xanthoxylum should be restored separately at different areas in the WOD.Overall,this study provides a better understanding of water use strategies of these four plants and scien-tific evidence for protecting rare and endangered plants,maintain-ing regional species diversity,and developing effective vegetation restoration plans in the WOD.展开更多
Aims Drought affected by atmosphere–ocean cycle is a dominant factor influencing tree radial growth of sandy Mongolian pine(Pinus sylvestris var.mongolica)and regional vegetation dynamics in Hulunbuir,China.However,h...Aims Drought affected by atmosphere–ocean cycle is a dominant factor influencing tree radial growth of sandy Mongolian pine(Pinus sylvestris var.mongolica)and regional vegetation dynamics in Hulunbuir,China.However,historical droughts and its correlations with tree radial growth and atmosphere–ocean cycle in this area have been little tested.Methods We developed tree-ring chronologies of Mongolian pine from Hulunbuir,Inner Mongolia,China and analyzed the correlations between tree-ring width index,the normalized difference vegetation index and Palmer drought severity index(PDSI),then developed a linear model to reconstruct the drought variability from 1829 to 2009.Long-term trends and its linkages with atmosphere–ocean cycle were performed by the power spectral,wavelet and teleconnection analysis.Important Findings The local moisture variations affected largely the regional vegetation dynamics and tree-ring growth of Mongolia pine in the forest–grassland transition.Using tree-ring width chronology of Mongolian pine,the reconstruction explains 49.2%of PDSI variance during their common data period(1951–2005).The reconstruction gives a broad-scale regional representation of PDSI in the Hulunbuir area,with drought occurrences in the 1850s,1900s,1920s,mid-1930s and at the turn of the 21st century.Comparisons with other treering drought reconstructions and historical records reveal some common drought periods and drying trends in recent decades at the northern margin zones of the East Asian summer monsoon(EASM).The drying trends in these zones occurred earlier than weakening of the EASM.A REDFIT spectral analysis shows significant peaks at 7.2,3.9,2.7–2.8,2.4 and 2.2 years with a 0.05 significance level,and 36.9,18.1 and 5.0 years with 0.1 significance level.Wavelet analysis also shows similar cycles.Drought variations in the study area significantly correlated with sea surface temperatures in the western tropical Pacific Ocean and middle and northern Indian Ocean,and the Pacific Decadal Oscillation and North Atlantic Oscillation.This suggests a possible linkage with the El Niño-Southern Oscillation,the EASM and the Westerlies.展开更多
基金National Natural Science Foundation of China(31170661,31290223)Special Research Program for Public-Welfare Forestry(201504423)Agriculture Science Technology Achievement Transformation Fund(2013GB24320620).
文摘Aims West Ordos Desert(WOD)in Inner Mongolia of China is charac-terized by unique geographical and ecological features to avoid the direct invasion of Quaternary Continental Glaciation,so it hosts many endangered relic species such as Tetraena mongol-ica,Ammopiptanthus mongolicus and Potaninia mongolica from Tertiary.However,how these plants utilize available water sources remains unknown.The objective of this study was to investigate the water utilization strategies of selected rare and endangered plant species in WOD by comparing hydrogen isotope ratios between their xylem water and possible water sources following four rainfall events of varying-intensities.Methods We measured the hydrogen isotope ratios of xylem water from T.mongolica,A.mongolicus and P.mongolica and an accom-panying species Sarcozygium xanthoxylum and potential water sources(including precipitation and soil water in different soil layers from 0 to 150 cm)over 9 days following each of four varying-intensity rainfall events during the summer of 2012.And then calculated the percentage utilization of potential water sources by each species after each rainfall events using the linear mixing model.We also made the measurements of soil moisture and root biomass in favor of interpretation of plant water use strategies.Important Findings Tetraena mongolica,A.mongolicus and S.xanthoxylum primarily relied on deep soil water,whereas P.mongolica depended predomi-nantly on rainwater.These rare and endangered desert plants had differential utilizations of available water sources,so some com-petition for limited water existed among some species.Tetraena mongolica had a competitive relationship in absorption of soil moisture with the same family species S.xanthoxylum,suggesting that T.mongolica and S.xanthoxylum should be restored separately at different areas in the WOD.Overall,this study provides a better understanding of water use strategies of these four plants and scien-tific evidence for protecting rare and endangered plants,maintain-ing regional species diversity,and developing effective vegetation restoration plans in the WOD.
基金‘948’Project of State Forestry Administration China(2015-4-27)International S&T Cooperation Program of China(2015DFR31130)+1 种基金National Natural Science Foundation of China(41271033,41471029 and 41371500)The Lecture and Study Program for Outstanding Scholars from Home and Abroad(CAFYBB2011007).
文摘Aims Drought affected by atmosphere–ocean cycle is a dominant factor influencing tree radial growth of sandy Mongolian pine(Pinus sylvestris var.mongolica)and regional vegetation dynamics in Hulunbuir,China.However,historical droughts and its correlations with tree radial growth and atmosphere–ocean cycle in this area have been little tested.Methods We developed tree-ring chronologies of Mongolian pine from Hulunbuir,Inner Mongolia,China and analyzed the correlations between tree-ring width index,the normalized difference vegetation index and Palmer drought severity index(PDSI),then developed a linear model to reconstruct the drought variability from 1829 to 2009.Long-term trends and its linkages with atmosphere–ocean cycle were performed by the power spectral,wavelet and teleconnection analysis.Important Findings The local moisture variations affected largely the regional vegetation dynamics and tree-ring growth of Mongolia pine in the forest–grassland transition.Using tree-ring width chronology of Mongolian pine,the reconstruction explains 49.2%of PDSI variance during their common data period(1951–2005).The reconstruction gives a broad-scale regional representation of PDSI in the Hulunbuir area,with drought occurrences in the 1850s,1900s,1920s,mid-1930s and at the turn of the 21st century.Comparisons with other treering drought reconstructions and historical records reveal some common drought periods and drying trends in recent decades at the northern margin zones of the East Asian summer monsoon(EASM).The drying trends in these zones occurred earlier than weakening of the EASM.A REDFIT spectral analysis shows significant peaks at 7.2,3.9,2.7–2.8,2.4 and 2.2 years with a 0.05 significance level,and 36.9,18.1 and 5.0 years with 0.1 significance level.Wavelet analysis also shows similar cycles.Drought variations in the study area significantly correlated with sea surface temperatures in the western tropical Pacific Ocean and middle and northern Indian Ocean,and the Pacific Decadal Oscillation and North Atlantic Oscillation.This suggests a possible linkage with the El Niño-Southern Oscillation,the EASM and the Westerlies.
