温度和降水变化显著影响高寒生态系统植被生长和系统功能。草地生产力作为草地系统功能强弱的重要体现,对气候变化,特别是温度和降水变化十分敏感。探究高寒草原生产力如何响应气候变化,对预测未来气候变化情景下高寒草地系统功能变化...温度和降水变化显著影响高寒生态系统植被生长和系统功能。草地生产力作为草地系统功能强弱的重要体现,对气候变化,特别是温度和降水变化十分敏感。探究高寒草原生产力如何响应气候变化,对预测未来气候变化情景下高寒草地系统功能变化意义重大。前期研究大都从年或季节尺度探究气候变化对草地生产力的影响特征,缺乏更精细时间尺度的关联分析。本研究基于1997—2020年青藏高原高寒草原长期植被观测数据及相应气候资料,应用简单线性回归及偏最小二乘回归法(Partial Least Squares regression,PLS)探究了研究区草地地上净初级生产力对日尺度温度和降水变化响应特征。结果表明:(1)近24 a来研究区年平均气温和降水量分别以0.03℃/a和4.36 mm/a的速率显著升高;(2)近24 a来研究区草地生产力显著升高(增幅为5.24 g m^(-2)a^(-1)),且与年平均温度和降水量呈显著正相关关系;(3)日尺度分析表明,不同阶段温度和降水变化对草地生产力的影响不同,其中5—8月和9—10月的温度及5—7月和9—11月的降水是影响研究区草地生产力的气候因子关键作用期,尤以生长季温度(5—8月)和降水(5—7月)变化影响更高,这表明生长季气候变化是该高寒草地生产力变化的主要驱动因素。总之,本研究指出近24 a生长季温度和降水量显著增加对高寒草原生产力具有重要促进作用,这意味着青藏高原暖湿化对高寒草原生态系统功能(草地生产力)影响不仅依赖于温度和降水变化的幅度,同时亦与温度和降水变化的方向和是否同步密切相关。展开更多
Phytoremediation can be used as a sustainable technology for mine spoil remediation to remove heavy metals. This study investigated the concentration of 7 heavy metal contamination in soil and plant samples at an aban...Phytoremediation can be used as a sustainable technology for mine spoil remediation to remove heavy metals. This study investigated the concentration of 7 heavy metal contamination in soil and plant samples at an abandoned mine site. We found that, after vegetation remediation at the abandoned mine site, the reduction rates for 7 heavy metals were in the range of 4.2%-86%, where reduction rates over 50% were achieved for four heavy metals （Zn, Mn, Cd, Ni）. Transfer coefficients of the panicled goldenrain tree （Koelreuteria paniculata Laxm） and the common elaeocarpus （Elaeocarpus decipens） for Zn, Mn, Ni, and Co were more than 1. Enrichment coefficients of both trees for Mn were higher than 1. Our results suggest that the panicled goldenrain tree and the common elaeocarpus tree may act as accumulators in remediation. Moreover, the woody vegetation remediation in abandoned mining areas play an important role in improving scenery besides removing heavy metal from contaminated soil.展开更多
目的初步探讨改良小切口劈腓肠肌内侧头入路治疗后交叉韧带(PCL)胫骨止点骨折的临床疗效。方法回顾性分析2013年12月至2016年2月乐昌市人民医院及解放军第198医院采用改良小切口劈腓肠肌内侧头入路治疗的18例PCL胫骨止点骨折患者的临床...目的初步探讨改良小切口劈腓肠肌内侧头入路治疗后交叉韧带(PCL)胫骨止点骨折的临床疗效。方法回顾性分析2013年12月至2016年2月乐昌市人民医院及解放军第198医院采用改良小切口劈腓肠肌内侧头入路治疗的18例PCL胫骨止点骨折患者的临床资料,观察手术时间、术中出血量,术后引流量、骨折愈合时间、后抽屉试验结果、骨折复位及并发症发生情况,末次随访时根据膝关节Lysholm评分评估膝关节功能。结果手术时间25~40 min,平均手术时间36 min;术中出血量10~15 m L,平均出血量12 m L;术后引流量10~20 m L,平均引流量16 m L。随访时间9~24个月(平均18个月)。骨折复位良好,无切口感染及血管、神经损伤。术后1个月后抽屉试验均为阴性。骨折顺利愈合,愈合时间2~5个月(平均3个月)。末次随访时膝关节功能Lysholm评分:优12例、良5例、可1例,优良率17/18。结论改良小切口劈腓肠肌内侧头入路治疗PCL胫骨止点骨折具有操作简单、安全微创、骨折复位效果好、骨折愈合率高、膝关节功能恢复理想等优点,近期疗效显著。展开更多
目的:观察桡骨远端骨折患者分别采用传统手法复位石膏外固定与手术内固定治疗的效果。方法:选取2017年1月-2018年7月笔者所在医院骨科收治的79例桡骨远端骨折患者作为研究对象,根据治疗方案的不同将其分为研究组(49例)和对照组(30例)。...目的:观察桡骨远端骨折患者分别采用传统手法复位石膏外固定与手术内固定治疗的效果。方法:选取2017年1月-2018年7月笔者所在医院骨科收治的79例桡骨远端骨折患者作为研究对象,根据治疗方案的不同将其分为研究组(49例)和对照组(30例)。研究组采用传统手法复位+石膏外固定制动治疗,对照组采用切开复位内固定手术治疗。比较两组治疗后6周,3、6个月疼痛程度、骨折复位效果及腕关节功能优良率。结果:两组治疗后6周、3个月时复位效果评分比较,差异均有统计学意义(P<0.05),但两组治疗后6个月复位效果评分比较,差异无统计学意义(P>0.05)。治疗前两组VAS评分比较差异无统计学意义(P>0.05);治疗后6周、3、6个月两组VAS评分比较差异均无统计学意义(P>0.05)。治疗后6周、3个月两组Gartland and Werley腕关节功能评分优良率比较,差异均无统计学意义(P>0.05),治疗后6个月,研究组Gartland and Werley腕关节功能评分优良率为98.0%,明显高于对照组的86.7%,差异有统计学意义(P<0.05)。结论:对于桡骨远端骨折患者,采用传统手法复位+石膏外固定制动治疗,治疗后6周、3个月时复位效果更好,但治疗后6个月的复位效果与切开复位内固定手术治疗相当,治疗后6个月腕关节功能恢复更好,值得推广。展开更多
Phenological changes play a central role in regulating seasonal variation in the ecological processes,exerting significant impacts on hydrologic and nutrient cycles,and ultimately influencing ecosystem functioning suc...Phenological changes play a central role in regulating seasonal variation in the ecological processes,exerting significant impacts on hydrologic and nutrient cycles,and ultimately influencing ecosystem functioning such as carbon uptake.However,the potential impact mechanisms of phenological events on seasonal carbon dynamics in subtropical regions are under-investigated.These knowledge gaps hinder from accurately linking photosynthetic phenology and carbon sequestration capacity.Using chlorophyll fluorescence remote sensing and productivity data from 2000 to 2019,we found that an advancement in spring phenology increased spring gross(GPP)and net primary productivity(NPP)in subtropical vegetation of China by 2.1 gC m^(-2)yr^(-1)and 1.4 gC m^(-2)yr^(-1),respectively.A delay in autumn phenology increased the autumnal GPP and NPP by 0.4 gC m^(-2)yr^(-1)and 0.2 gC m^(-2)yr^(-1),respectively.Temporally,the contribution of the spring phenology to spring carbon uptake increased significantly during the study period,while this positive contribution showed a nonsignificant trend in summer.In comparison,the later autumn phenology could significantly contribute to the increase in autumnal carbon uptake;however,this contributing effect was weakened.Path analysis indicated that these phenomena have been caused by the increased leaf area and enhanced photosynthesis due to earlier spring and later autumn phenology,respectively.Our results demonstrate the diverse impacts of vegetation phenology on the seasonal carbon sequestration ability and it is imperative to consider such asymmetric effects when modeling ecosystem processes parameterized under future climate change.展开更多
Meta-analysis is a quantitative synthetic research method that statistically integrates results from in- dividual studies to find common trends and differences. With increasing concern over global change, meta-analysi...Meta-analysis is a quantitative synthetic research method that statistically integrates results from in- dividual studies to find common trends and differences. With increasing concern over global change, meta-analysis has been rapidly adopted in global change research. Here, we introduce the methodolo- gies, advantages and disadvantages of meta-analysis, and review its application in global climate change research, including the responses of ecosystems to global warming and rising CO2 and O3 concentrations, the effects of land use and management on climate change and the effects of distur- bances on biogeochemistry cycles of ecosystem. Despite limitation and potential misapplication, meta-analysis has been demonstrated to be a much better tool than traditional narrative review in synthesizing results from multiple studies. Several methodological developments for research synthe- sis have not yet been widely used in global climate change researches such as cumulative meta-analysis and sensitivity analysis. It is necessary to update the results of meta-analysis on a given topic at regular intervals by including newly published studies. Emphasis should be put on multi-factor interaction and long-term experiments. There is great potential to apply meta-analysis to global climate change research in China because research and observation networks have been established (e.g. ChinaFlux and CERN), which create the need for combining these data and results to provide support for governments’ decision making on climate change. It is expected that meta-analysis will be widely adopted in future climate change research.展开更多
Fields that employ artificial neural networks(ANNs)have developed and expanded continuously in recent years with the ongoing development of computer technology and artificial intelligence.ANN has been adopted widely a...Fields that employ artificial neural networks(ANNs)have developed and expanded continuously in recent years with the ongoing development of computer technology and artificial intelligence.ANN has been adopted widely and put into practice by research-ers in light of increasing concerns over ecological issues such as global warming,frequent El Nio-Southern Oscillation(ENSO)events,and atmospheric circulation anomalies.Limitations exist and there is a potential risk for misuse in that ANN model pa-rameters require typically higher overall sensitivity,and the chosen network structure is generally more dependent upon individ-ual experience.ANNs,however,are relatively accurate when used for short-term predictions;despite global climate change re-search favoring the effects of interactions as the basis of study and the preference for long-term experimental research.ANNs remain a better choice than many traditional methods when dealing with nonlinear problems,and possesses great potential for the study of global climate change and ecological issues.ANNs can resolve problems that other methods cannot.This is especially true for situations in which measurements are difficult to conduct or when only incomplete data are available.It is anticipated that ANNs will be widely adopted and then further developed for global climate change and ecological research.展开更多
Model simulation and in situ observations are often used to research water and carbon cycles in terrestrial ecosystems, but each of these methods has its own advantages and limitations. Combining these two methods cou...Model simulation and in situ observations are often used to research water and carbon cycles in terrestrial ecosystems, but each of these methods has its own advantages and limitations. Combining these two methods could improve the accuracy of quantifying the dynamics of the water and carbon fluxes of an ecosystem. Data assimilation is an effective means of integrating modeling with in situ observation. In this study, the ensemble Kalman filter(En KF) and the unscented Kalman filter(UKF) algorithms were used to assimilate remotely sensed leaf area index(LAI) data with the Biome-BGC model to simulate water and carbon fluxes at the Harvard Forest Environmental Monitoring Site(EMS) and the Dinghushan site. After MODIS LAI data from 2000–2004 were assimilated into the improved Biome-BGC model using the En KF algorithm at the Harvard Forest site, the R2 between the simulated and observed results for NEE and evapotranspiration increased by 7.8% and 4.7%, respectively. In addition, the sum of the absolute error(SAE) and the root mean square error(RMSE) of NEE decreased by an average of 21.9% and 26.3%, and the SAE and RMSE of evapotranspiration decreased by 24.5% and 25.5%, respectively. MODIS LAI data of 2003 were assimilated into the Biome-BGC model for the Dinghushan site, and the R2 values between the simulated and observed results for NEE and evapotranspiration were increased by 6.7% and 17.3%, respectively. In addition, the SAE values of NEE and ET were decreased by 11.3% and 30.7%, respectively, and the RMSE values of NEE and ET decreased by 10.1% and 30.9%, respectively. These results demonstrate that the accuracy of carbon and water flux simulations can be effectively improved when remotely sensed LAI data are properly integrated with ecosystem models through a data assimilation approach.展开更多
文摘温度和降水变化显著影响高寒生态系统植被生长和系统功能。草地生产力作为草地系统功能强弱的重要体现,对气候变化,特别是温度和降水变化十分敏感。探究高寒草原生产力如何响应气候变化,对预测未来气候变化情景下高寒草地系统功能变化意义重大。前期研究大都从年或季节尺度探究气候变化对草地生产力的影响特征,缺乏更精细时间尺度的关联分析。本研究基于1997—2020年青藏高原高寒草原长期植被观测数据及相应气候资料,应用简单线性回归及偏最小二乘回归法(Partial Least Squares regression,PLS)探究了研究区草地地上净初级生产力对日尺度温度和降水变化响应特征。结果表明:(1)近24 a来研究区年平均气温和降水量分别以0.03℃/a和4.36 mm/a的速率显著升高;(2)近24 a来研究区草地生产力显著升高(增幅为5.24 g m^(-2)a^(-1)),且与年平均温度和降水量呈显著正相关关系;(3)日尺度分析表明,不同阶段温度和降水变化对草地生产力的影响不同,其中5—8月和9—10月的温度及5—7月和9—11月的降水是影响研究区草地生产力的气候因子关键作用期,尤以生长季温度(5—8月)和降水(5—7月)变化影响更高,这表明生长季气候变化是该高寒草地生产力变化的主要驱动因素。总之,本研究指出近24 a生长季温度和降水量显著增加对高寒草原生产力具有重要促进作用,这意味着青藏高原暖湿化对高寒草原生态系统功能(草地生产力)影响不仅依赖于温度和降水变化的幅度,同时亦与温度和降水变化的方向和是否同步密切相关。
基金As a key project under the State Forestry Administration of China (2006-11, 2006-17, 2005-08)this project was funded by the National Natural Science Foundation of China (No. 30571487, 30771700)+1 种基金the Furong Scholar Program, the Urban Forest Ecological Key Laboratory of Hunan Province (No. 06FJ3083)the Platform Construction Project under the Ministry of Science and Technology of China
文摘Phytoremediation can be used as a sustainable technology for mine spoil remediation to remove heavy metals. This study investigated the concentration of 7 heavy metal contamination in soil and plant samples at an abandoned mine site. We found that, after vegetation remediation at the abandoned mine site, the reduction rates for 7 heavy metals were in the range of 4.2%-86%, where reduction rates over 50% were achieved for four heavy metals （Zn, Mn, Cd, Ni）. Transfer coefficients of the panicled goldenrain tree （Koelreuteria paniculata Laxm） and the common elaeocarpus （Elaeocarpus decipens） for Zn, Mn, Ni, and Co were more than 1. Enrichment coefficients of both trees for Mn were higher than 1. Our results suggest that the panicled goldenrain tree and the common elaeocarpus tree may act as accumulators in remediation. Moreover, the woody vegetation remediation in abandoned mining areas play an important role in improving scenery besides removing heavy metal from contaminated soil.
文摘目的初步探讨改良小切口劈腓肠肌内侧头入路治疗后交叉韧带(PCL)胫骨止点骨折的临床疗效。方法回顾性分析2013年12月至2016年2月乐昌市人民医院及解放军第198医院采用改良小切口劈腓肠肌内侧头入路治疗的18例PCL胫骨止点骨折患者的临床资料,观察手术时间、术中出血量,术后引流量、骨折愈合时间、后抽屉试验结果、骨折复位及并发症发生情况,末次随访时根据膝关节Lysholm评分评估膝关节功能。结果手术时间25~40 min,平均手术时间36 min;术中出血量10~15 m L,平均出血量12 m L;术后引流量10~20 m L,平均引流量16 m L。随访时间9~24个月(平均18个月)。骨折复位良好,无切口感染及血管、神经损伤。术后1个月后抽屉试验均为阴性。骨折顺利愈合,愈合时间2~5个月(平均3个月)。末次随访时膝关节功能Lysholm评分:优12例、良5例、可1例,优良率17/18。结论改良小切口劈腓肠肌内侧头入路治疗PCL胫骨止点骨折具有操作简单、安全微创、骨折复位效果好、骨折愈合率高、膝关节功能恢复理想等优点,近期疗效显著。
文摘目的:观察桡骨远端骨折患者分别采用传统手法复位石膏外固定与手术内固定治疗的效果。方法:选取2017年1月-2018年7月笔者所在医院骨科收治的79例桡骨远端骨折患者作为研究对象,根据治疗方案的不同将其分为研究组(49例)和对照组(30例)。研究组采用传统手法复位+石膏外固定制动治疗,对照组采用切开复位内固定手术治疗。比较两组治疗后6周,3、6个月疼痛程度、骨折复位效果及腕关节功能优良率。结果:两组治疗后6周、3个月时复位效果评分比较,差异均有统计学意义(P<0.05),但两组治疗后6个月复位效果评分比较,差异无统计学意义(P>0.05)。治疗前两组VAS评分比较差异无统计学意义(P>0.05);治疗后6周、3、6个月两组VAS评分比较差异均无统计学意义(P>0.05)。治疗后6周、3个月两组Gartland and Werley腕关节功能评分优良率比较,差异均无统计学意义(P>0.05),治疗后6个月,研究组Gartland and Werley腕关节功能评分优良率为98.0%,明显高于对照组的86.7%,差异有统计学意义(P<0.05)。结论:对于桡骨远端骨折患者,采用传统手法复位+石膏外固定制动治疗,治疗后6周、3个月时复位效果更好,但治疗后6个月的复位效果与切开复位内固定手术治疗相当,治疗后6个月腕关节功能恢复更好,值得推广。
基金National Natural Science Foundation of China,No.42371121Joint Fund for Regional Innovation and Development of the National Natural Science Foundation of China,No.U22A20570Science and Technology Innovation Program of Hunan Province,China,No.2022RC4027。
文摘Phenological changes play a central role in regulating seasonal variation in the ecological processes,exerting significant impacts on hydrologic and nutrient cycles,and ultimately influencing ecosystem functioning such as carbon uptake.However,the potential impact mechanisms of phenological events on seasonal carbon dynamics in subtropical regions are under-investigated.These knowledge gaps hinder from accurately linking photosynthetic phenology and carbon sequestration capacity.Using chlorophyll fluorescence remote sensing and productivity data from 2000 to 2019,we found that an advancement in spring phenology increased spring gross(GPP)and net primary productivity(NPP)in subtropical vegetation of China by 2.1 gC m^(-2)yr^(-1)and 1.4 gC m^(-2)yr^(-1),respectively.A delay in autumn phenology increased the autumnal GPP and NPP by 0.4 gC m^(-2)yr^(-1)and 0.2 gC m^(-2)yr^(-1),respectively.Temporally,the contribution of the spring phenology to spring carbon uptake increased significantly during the study period,while this positive contribution showed a nonsignificant trend in summer.In comparison,the later autumn phenology could significantly contribute to the increase in autumnal carbon uptake;however,this contributing effect was weakened.Path analysis indicated that these phenomena have been caused by the increased leaf area and enhanced photosynthesis due to earlier spring and later autumn phenology,respectively.Our results demonstrate the diverse impacts of vegetation phenology on the seasonal carbon sequestration ability and it is imperative to consider such asymmetric effects when modeling ecosystem processes parameterized under future climate change.
基金International Partnership Project "Human Activities and Ecosystem Changes", Chinese Academy of Sciences (Grant No. CXTD-Z2005-1)Natural Science and Engineering Research Council of Canada (NSERC)China Scholarship Council (CSC)
文摘Meta-analysis is a quantitative synthetic research method that statistically integrates results from in- dividual studies to find common trends and differences. With increasing concern over global change, meta-analysis has been rapidly adopted in global change research. Here, we introduce the methodolo- gies, advantages and disadvantages of meta-analysis, and review its application in global climate change research, including the responses of ecosystems to global warming and rising CO2 and O3 concentrations, the effects of land use and management on climate change and the effects of distur- bances on biogeochemistry cycles of ecosystem. Despite limitation and potential misapplication, meta-analysis has been demonstrated to be a much better tool than traditional narrative review in synthesizing results from multiple studies. Several methodological developments for research synthe- sis have not yet been widely used in global climate change researches such as cumulative meta-analysis and sensitivity analysis. It is necessary to update the results of meta-analysis on a given topic at regular intervals by including newly published studies. Emphasis should be put on multi-factor interaction and long-term experiments. There is great potential to apply meta-analysis to global climate change research in China because research and observation networks have been established (e.g. ChinaFlux and CERN), which create the need for combining these data and results to provide support for governments’ decision making on climate change. It is expected that meta-analysis will be widely adopted in future climate change research.
基金supported by the Introducing Advanced Technology Program(948Pro-gram)(2010-4-03)the New Century Excellent Talents Program from the Ministry of Education,China(NCET-06-0715)+1 种基金the Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Provincethe Furong Scholar Program
文摘Fields that employ artificial neural networks(ANNs)have developed and expanded continuously in recent years with the ongoing development of computer technology and artificial intelligence.ANN has been adopted widely and put into practice by research-ers in light of increasing concerns over ecological issues such as global warming,frequent El Nio-Southern Oscillation(ENSO)events,and atmospheric circulation anomalies.Limitations exist and there is a potential risk for misuse in that ANN model pa-rameters require typically higher overall sensitivity,and the chosen network structure is generally more dependent upon individ-ual experience.ANNs,however,are relatively accurate when used for short-term predictions;despite global climate change re-search favoring the effects of interactions as the basis of study and the preference for long-term experimental research.ANNs remain a better choice than many traditional methods when dealing with nonlinear problems,and possesses great potential for the study of global climate change and ecological issues.ANNs can resolve problems that other methods cannot.This is especially true for situations in which measurements are difficult to conduct or when only incomplete data are available.It is anticipated that ANNs will be widely adopted and then further developed for global climate change and ecological research.
基金supported by the National Natural Science Foundation of China(Grant Nos.41301451&41471349)the Fundamental Research Funds for the Central Universities(Grant No.QN2013074)China’s Qian-Ren Program
文摘Model simulation and in situ observations are often used to research water and carbon cycles in terrestrial ecosystems, but each of these methods has its own advantages and limitations. Combining these two methods could improve the accuracy of quantifying the dynamics of the water and carbon fluxes of an ecosystem. Data assimilation is an effective means of integrating modeling with in situ observation. In this study, the ensemble Kalman filter(En KF) and the unscented Kalman filter(UKF) algorithms were used to assimilate remotely sensed leaf area index(LAI) data with the Biome-BGC model to simulate water and carbon fluxes at the Harvard Forest Environmental Monitoring Site(EMS) and the Dinghushan site. After MODIS LAI data from 2000–2004 were assimilated into the improved Biome-BGC model using the En KF algorithm at the Harvard Forest site, the R2 between the simulated and observed results for NEE and evapotranspiration increased by 7.8% and 4.7%, respectively. In addition, the sum of the absolute error(SAE) and the root mean square error(RMSE) of NEE decreased by an average of 21.9% and 26.3%, and the SAE and RMSE of evapotranspiration decreased by 24.5% and 25.5%, respectively. MODIS LAI data of 2003 were assimilated into the Biome-BGC model for the Dinghushan site, and the R2 values between the simulated and observed results for NEE and evapotranspiration were increased by 6.7% and 17.3%, respectively. In addition, the SAE values of NEE and ET were decreased by 11.3% and 30.7%, respectively, and the RMSE values of NEE and ET decreased by 10.1% and 30.9%, respectively. These results demonstrate that the accuracy of carbon and water flux simulations can be effectively improved when remotely sensed LAI data are properly integrated with ecosystem models through a data assimilation approach.
