Extreme precipitation events are one of the most dangerous hydrometeorological disasters,often resulting in significant human and socio-economic losses worldwide.It is therefore important to use current global climate...Extreme precipitation events are one of the most dangerous hydrometeorological disasters,often resulting in significant human and socio-economic losses worldwide.It is therefore important to use current global climate models to project future changes in precipitation extremes.The present study aims to assess the future changes in precipitation extremes over South Asia from the Coupled Model Intercomparison Project Phase 6(CMIP6)Global Climate Models(GCMs).The results were derived using the modified Mann-Kendall test,Sen's slope estimator,student's t-test,and probability density function approach.Eight extreme precipitation indices were assessed,including wet days(RR1mm),heavy precipitation days(RR10mm),very heavy precipitation days(RR20mm),severe precipitation days(RR50mm),consecutive wet days(CWD),consecutive dry days(CDD),maximum 5-day precipitation amount(RX5day),and simple daily intensity index(SDII).The future changes were estimated in two time periods for the 21^(st) century(i.e.,near future(NF;2021-2060)and far future(FF;2061-2100))under two Shared Socioeconomic Pathway(SSP)scenarios(SSP2-4.5 and SSP5-8.5).The results suggest increases in the frequency and intensity of extreme precipitation indices under the SSP5-8.5 scenario towards the end of the 21^(st) century(2061-2100).Moreover,from the results of multimodel ensemble means(MMEMs),extreme precipitation indices of RR1mm,RR10mm,RR20mm,CWD,and SDII demonstrate remarkable increases in the FF period under the SSP5-8.5 scenario.The spatial distribution of extreme precipitation indices shows intensification over the eastern part of South Asia compared to the western part.The probability density function of extreme precipitation indices suggests a frequent(intense)occurrence of precipitation extremes in the FF period under the SSP5-8.5 scenario,with values up to 35.00 d for RR1mm and 25.00-35.00 d for CWD.The potential impacts of heavy precipitation can pose serious challenges to the study area regarding flooding,soil erosion,water resource management,food security,and agriculture development.展开更多
The replacement of native dry forests by commercial(exotic)tree plantations could generate changes in rainfall partitioning,which further affects the water cycle.In this study,we determined(i)the rainfall partitioning...The replacement of native dry forests by commercial(exotic)tree plantations could generate changes in rainfall partitioning,which further affects the water cycle.In this study,we determined(i)the rainfall partitioning into interception,throughfall and stemflow,(ii)the role of rainfall event size on rainfall partitioning,(iii)the pH of water channelized as throughfall and stemflow,and(iv)the runoff in Lithraea molleoides(a native species)and Pinus elliottii(an exotic species)stands in the dry Chaco mountain forests,central Argentina.On average,interception,throughfall and stemflow accounted for 19.3%,79.5%and 1.2%of the gross rainfall in L.molleoides stand,and 32.6%,66.7%and 0.7%of the gross rainfall in P.elliottii stand,respectively.Amounts of interception,throughfall and stemflow presented positive linear relationships with the increment of rainfall event size for both tree species(P<0.01 in all cases).Percentages of interception,throughfall and stemflow were all related to the increment of rainfall event size,showing different patterns.With increasing rainfall event size,interception exponentially decreased,throughfall asymptotically increased and stemflow linearly increased.Both P.elliottii and L.molleoides stands presented significant differences in the pH values of water channelized as throughfall(6.3 vs.6.7,respectively;P<0.01)and stemflow(4.5 vs.5.8,respectively;P<0.01).Runoff occupied only 0.3%of the gross rainfall in P.elliottii stand and was zero in L.molleoides stand.Our results showed that the native species L.molleoides presented 13.6%more water reaching the topsoil(i.e.,net rainfall;net rainfall=gross rainfall-interception-runoff)than the exotic species P.elliottii.This study improves our understanding of the effects of native vegetation replacement on the local water balance in the dry forest ecosystems.展开更多
Aims Riparian plant diversity is sensitive to changes in groundwater in arid regions.However,little is known about how plant diversity responds to changes in environment along riverside-desert gradi-ents in riparian e...Aims Riparian plant diversity is sensitive to changes in groundwater in arid regions.However,little is known about how plant diversity responds to changes in environment along riverside-desert gradi-ents in riparian ecosystem.Our objectives were to(i)identify ri-parian plant diversity along riverside-desert gradients in Tarim desert riparian forests,(ii)analyze the impact of environment variables on plant diversity,(iii)determine the optimum groundwater depth for different plant life-forms.Methods Six transects 90 quadrats(with each size 100 m×100 m)distributed vertically to river bed along riverside-desert gradients~30 km in length were surveyed.At each quadrat,the morphological features of riparian plant communities were measured,and the groundwater depth,soil water,soil salinity,soil nutrient were also monitored at same sites.Important Finding Three distinct vegetation communities were identified based on cover and richness in the tree,shrub and herb layers:the riparian zone,the transitional zone and the desert margin zone.Twelve spe-cies were indicators of the three vegetation communities.Riparian plant diversity was influenced by groundwater depth,distance from river,soil moisture content,soil salinity and soil nutrient by redundancy analysis.In response to groundwater depth,the op-timal groundwater depths for species diversity,evenness and shrub cover were 2.8,2.7 and 3.7 m,respectively.Therefore,maintaining high plant diversity requires managers to ensure stable groundwater depth for different plant life-forms rather than for some of them.展开更多
基金supported by the National Natural Science Foundation of China(42130405)the Innovative and Entrepreneurial Talent Program of Jiangsu Province(R2020SC04)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA2006030201)the Research Fund for International Young Scientists of the National Natural Science Foundation of China(42150410381).
文摘Extreme precipitation events are one of the most dangerous hydrometeorological disasters,often resulting in significant human and socio-economic losses worldwide.It is therefore important to use current global climate models to project future changes in precipitation extremes.The present study aims to assess the future changes in precipitation extremes over South Asia from the Coupled Model Intercomparison Project Phase 6(CMIP6)Global Climate Models(GCMs).The results were derived using the modified Mann-Kendall test,Sen's slope estimator,student's t-test,and probability density function approach.Eight extreme precipitation indices were assessed,including wet days(RR1mm),heavy precipitation days(RR10mm),very heavy precipitation days(RR20mm),severe precipitation days(RR50mm),consecutive wet days(CWD),consecutive dry days(CDD),maximum 5-day precipitation amount(RX5day),and simple daily intensity index(SDII).The future changes were estimated in two time periods for the 21^(st) century(i.e.,near future(NF;2021-2060)and far future(FF;2061-2100))under two Shared Socioeconomic Pathway(SSP)scenarios(SSP2-4.5 and SSP5-8.5).The results suggest increases in the frequency and intensity of extreme precipitation indices under the SSP5-8.5 scenario towards the end of the 21^(st) century(2061-2100).Moreover,from the results of multimodel ensemble means(MMEMs),extreme precipitation indices of RR1mm,RR10mm,RR20mm,CWD,and SDII demonstrate remarkable increases in the FF period under the SSP5-8.5 scenario.The spatial distribution of extreme precipitation indices shows intensification over the eastern part of South Asia compared to the western part.The probability density function of extreme precipitation indices suggests a frequent(intense)occurrence of precipitation extremes in the FF period under the SSP5-8.5 scenario,with values up to 35.00 d for RR1mm and 25.00-35.00 d for CWD.The potential impacts of heavy precipitation can pose serious challenges to the study area regarding flooding,soil erosion,water resource management,food security,and agriculture development.
基金the Secretary of Science and Technology of the National University of Córdoba(2014–2017)supported by a PhD grant from the National Research Council Scientific and Technical(Dr.Samia CORTÉS).
文摘The replacement of native dry forests by commercial(exotic)tree plantations could generate changes in rainfall partitioning,which further affects the water cycle.In this study,we determined(i)the rainfall partitioning into interception,throughfall and stemflow,(ii)the role of rainfall event size on rainfall partitioning,(iii)the pH of water channelized as throughfall and stemflow,and(iv)the runoff in Lithraea molleoides(a native species)and Pinus elliottii(an exotic species)stands in the dry Chaco mountain forests,central Argentina.On average,interception,throughfall and stemflow accounted for 19.3%,79.5%and 1.2%of the gross rainfall in L.molleoides stand,and 32.6%,66.7%and 0.7%of the gross rainfall in P.elliottii stand,respectively.Amounts of interception,throughfall and stemflow presented positive linear relationships with the increment of rainfall event size for both tree species(P<0.01 in all cases).Percentages of interception,throughfall and stemflow were all related to the increment of rainfall event size,showing different patterns.With increasing rainfall event size,interception exponentially decreased,throughfall asymptotically increased and stemflow linearly increased.Both P.elliottii and L.molleoides stands presented significant differences in the pH values of water channelized as throughfall(6.3 vs.6.7,respectively;P<0.01)and stemflow(4.5 vs.5.8,respectively;P<0.01).Runoff occupied only 0.3%of the gross rainfall in P.elliottii stand and was zero in L.molleoides stand.Our results showed that the native species L.molleoides presented 13.6%more water reaching the topsoil(i.e.,net rainfall;net rainfall=gross rainfall-interception-runoff)than the exotic species P.elliottii.This study improves our understanding of the effects of native vegetation replacement on the local water balance in the dry forest ecosystems.
基金This study was funded by the Key National Natural Science Foundation project(U1403281,41671030)and startup Foundation for Introducing Talent of NUIST.
文摘Aims Riparian plant diversity is sensitive to changes in groundwater in arid regions.However,little is known about how plant diversity responds to changes in environment along riverside-desert gradi-ents in riparian ecosystem.Our objectives were to(i)identify ri-parian plant diversity along riverside-desert gradients in Tarim desert riparian forests,(ii)analyze the impact of environment variables on plant diversity,(iii)determine the optimum groundwater depth for different plant life-forms.Methods Six transects 90 quadrats(with each size 100 m×100 m)distributed vertically to river bed along riverside-desert gradients~30 km in length were surveyed.At each quadrat,the morphological features of riparian plant communities were measured,and the groundwater depth,soil water,soil salinity,soil nutrient were also monitored at same sites.Important Finding Three distinct vegetation communities were identified based on cover and richness in the tree,shrub and herb layers:the riparian zone,the transitional zone and the desert margin zone.Twelve spe-cies were indicators of the three vegetation communities.Riparian plant diversity was influenced by groundwater depth,distance from river,soil moisture content,soil salinity and soil nutrient by redundancy analysis.In response to groundwater depth,the op-timal groundwater depths for species diversity,evenness and shrub cover were 2.8,2.7 and 3.7 m,respectively.Therefore,maintaining high plant diversity requires managers to ensure stable groundwater depth for different plant life-forms rather than for some of them.
