The effects of human activities on climate change are a significant area of research in the field of global environmental change.Land use and land cover change(LUCC)has a greater effect on climate than greenhouse gase...The effects of human activities on climate change are a significant area of research in the field of global environmental change.Land use and land cover change(LUCC)has a greater effect on climate than greenhouse gases,and the effect of farmland expansion on regional drought is particularly important.From the 1910s to the 2010s,cultivated land in Songnen Plain increased by 2.67 times,the area of cultivated land increased from 4.92×10^4 km^2 to 13.14×10^4 km^2,and its percentage of all land increased from 25%to 70%.This provides an opportunity to study the effects of the conversion of natural grassland to farmland on climate.In this study,the drought indices in Songnen Plain were evaluated from the 1910s to the 2010s,and the effect of farmland expansion on drought was investigated using statistical methods and the Weather Research and Forecasting Model based on UK’s Climatic Research Unit data.The resulting dryness index,Palmer drought severity index,and standardized precipitation index values indicated a significant drying trend in the study area from 1981 to 2010.This trend can be attributed to increases in maximum temperature and diurnal temperature range,which increased the degree of drought.Based on statistical analysis and simulation,the maximum temperature,diurnal temperature range,and sensible heat flux increased during the growing season in Songnen Plain over the past 100 years,while the minimum temperature and latent heat flux decreased.The findings indicate that farmland expansion caused a drying trend in Songnen Plain during the study period.展开更多
Extreme climate has increasingly led to negative impacts on forest ecosystems globally,especially in semiarid areas where forest ecosystems are more vulnerable.However,it is poorly understood how tree growth is affect...Extreme climate has increasingly led to negative impacts on forest ecosystems globally,especially in semiarid areas where forest ecosystems are more vulnerable.However,it is poorly understood how tree growth is affected by different drought events.In 2006–2009,the larch plantations in the semiarid areas of Northwest China were negatively affected by four consecutive dry years,which was a very rare phenomenon that may occur frequently under future climate warming.In this study,we analyzed the effect of these consecutive dry years on tree growth based on the data of the tree rings in the dominant layer of the forest canopy on a larch plantation.We found that the tree-ring width index(RWI)in dry years was lower than that in normal years,and it experienced a rapidly decreasing trend from 2006 to 2009(slope=-0.139 year^(-1),r=-0.94)due to water supply deficits in those dry years.Drought induced legacy effects of tree growth reduction,and consecutive dry years corresponded with greater growth reductions and legacy effects.Growth reductions and legacy effects were significantly stronger in the third and fourth consecutive dry years than that of single dry year(p<0.05),which might have been due to the cumulative stress caused by consecutive dry years.Our results showed that larch trees experienced greater tree growth reduction due to consecutive dry years and their legacy effect,and the trees had lower recovery rates after consecutive dry years.Our results highlight that consecutive dry years pose a new threat to plantations under climate warming,and thus,the effect of climate extremes on tree growth should be considered in growth models in semiarid areas.展开更多
The physiological effect of new FA antitranspirant on winter wheat was studied by field trial. The new FA antitranspirant was sprayed at ear filling stage, using the following concentrations： 0.5, 1.0, 1.5 and 2.0 mL...The physiological effect of new FA antitranspirant on winter wheat was studied by field trial. The new FA antitranspirant was sprayed at ear filling stage, using the following concentrations： 0.5, 1.0, 1.5 and 2.0 mL L^-1. The results indicated that new FA antitranspirant increased nitrate reductase activity （NRA）, free proline content, chlorophyll content and water content of leaf, thus drought stress can be mitigated. The new FA antitranspirant increased photosynthesis, enlarged stomatal conductance and reduced transpiration rate, thus led to growth stimulation and water loss reduction. New FA antitranspirant caused an increase of grain yield by 7.2%, under the optimal concentration 1.5 mL L^-1.展开更多
The field trial was conducted to study physiological effect of new FA antitranspirant on maize. The new FA antitranspirant was sprayed at 10 d pre-tasseling, ear filling stage and 10 d pre-tasseling + ear filling stag...The field trial was conducted to study physiological effect of new FA antitranspirant on maize. The new FA antitranspirant was sprayed at 10 d pre-tasseling, ear filling stage and 10 d pre-tasseling + ear filling stage, with the concentrations of 0, 0.5, 1.0, 1.5 and 2.0 ml L-1. The results indicated that the application of new FA antitranspirant increased nitrate reductase activity(NRA), free proline content, chlorophyll content and water content of leaf, thus drought stress can be mitigated. The new FA antitranspirant increased photosynthesis rate and reduced transpiration rate, stimulated growth and reduced water loss. 10 d pre-tasseling + ear filling stage application had a cumulative effect on the indices compared with 10 d pre-tasseling and ear filling stage, except for NRA. The new FA antitranspirant caused an increase of grain yield by 5.37 to 29. 58% with different treatments. The optimal concentration is 1. 5 ml L-1, i. e. 75 g new FA antitranspirant dissolved in 50 kg water, and the optimal apply period is 10 d pre-tasseling + ear filling stage.展开更多
植被总初级生产力(Gross Primary Productivity,GPP)是陆地生态系统碳汇的重要组成部分。深入理解干旱对植被GPP影响的累积效应和滞后效应,揭示植被响应机制,对云南省生态安全具有重要意义。然而,关于植被GPP干旱响应机制的时空异质性...植被总初级生产力(Gross Primary Productivity,GPP)是陆地生态系统碳汇的重要组成部分。深入理解干旱对植被GPP影响的累积效应和滞后效应,揭示植被响应机制,对云南省生态安全具有重要意义。然而,关于植被GPP干旱响应机制的时空异质性和影响因子的研究仍较为匮乏。研究基于2001—2023年植被GPP和标准化降水蒸散发指数数据,采用时间序列分析方法和最大相关系数法,分析了云南省气象干旱和植被GPP的时空变化特征,量化并探讨了干旱对植被GPP的累积效应与滞后效应,及其受长期干湿状况和海拔的影响。结果表明:(1)近23年以来,云南省总体上表现为不显著干旱化趋势。干旱的高发区域主要分布在西北部、西部和中东部,高发时段为春季和秋季。植被GPP多年均值为1600.2 g C/m^(2),年际变化表现为极显著上升趋势(6.8 g C m^(-2) a^(-1),P<0.001),但年际波动较为明显。(2)植被GPP对干旱的响应具有明显的时空异质性,以秋季和春季响应最为显著,空间上干热河谷地区最易受干旱影响,响应强烈且迅速。(3)全省52.0%和54.9%的区域植被GPP显著受干旱累积效应和滞后效应的影响。累积效应时间尺度以中短期(4—6个月)和长期(10—12个月)为主,滞后时间以长期(10—12个月)为主。相较灌木和森林,农田和草地对干旱的响应更强烈、时间尺度更短。滞后时间在不同植被类型间的差异较小。(4)长期干湿状况和海拔是影响干旱累积效应和滞后效应的重要因素。随着环境从干燥转为湿润或是海拔升高,干旱影响强度会逐渐降低,累积效应时间尺度延长,而滞后时间则缩短。海拔对干旱影响强度的作用大于干湿状况,而累积效应时间尺度和滞后时间受干湿状况的影响则更显著。研究结果可以为干旱风险缓解与应对管理策略的制定提供科学依据。展开更多
基金National Natural Science Foundation of China,No.41771067Natural Science Foundation of Heilongjiang Province,No.D2018007。
文摘The effects of human activities on climate change are a significant area of research in the field of global environmental change.Land use and land cover change(LUCC)has a greater effect on climate than greenhouse gases,and the effect of farmland expansion on regional drought is particularly important.From the 1910s to the 2010s,cultivated land in Songnen Plain increased by 2.67 times,the area of cultivated land increased from 4.92×10^4 km^2 to 13.14×10^4 km^2,and its percentage of all land increased from 25%to 70%.This provides an opportunity to study the effects of the conversion of natural grassland to farmland on climate.In this study,the drought indices in Songnen Plain were evaluated from the 1910s to the 2010s,and the effect of farmland expansion on drought was investigated using statistical methods and the Weather Research and Forecasting Model based on UK’s Climatic Research Unit data.The resulting dryness index,Palmer drought severity index,and standardized precipitation index values indicated a significant drying trend in the study area from 1981 to 2010.This trend can be attributed to increases in maximum temperature and diurnal temperature range,which increased the degree of drought.Based on statistical analysis and simulation,the maximum temperature,diurnal temperature range,and sensible heat flux increased during the growing season in Songnen Plain over the past 100 years,while the minimum temperature and latent heat flux decreased.The findings indicate that farmland expansion caused a drying trend in Songnen Plain during the study period.
基金the National Natural Science Foundation of China(Nos.42161144008U21A2005+3 种基金U20A2085)the National Key Research and Development Program of China(2022YFF08018042022YFF08018032022YFF1300404)。
文摘Extreme climate has increasingly led to negative impacts on forest ecosystems globally,especially in semiarid areas where forest ecosystems are more vulnerable.However,it is poorly understood how tree growth is affected by different drought events.In 2006–2009,the larch plantations in the semiarid areas of Northwest China were negatively affected by four consecutive dry years,which was a very rare phenomenon that may occur frequently under future climate warming.In this study,we analyzed the effect of these consecutive dry years on tree growth based on the data of the tree rings in the dominant layer of the forest canopy on a larch plantation.We found that the tree-ring width index(RWI)in dry years was lower than that in normal years,and it experienced a rapidly decreasing trend from 2006 to 2009(slope=-0.139 year^(-1),r=-0.94)due to water supply deficits in those dry years.Drought induced legacy effects of tree growth reduction,and consecutive dry years corresponded with greater growth reductions and legacy effects.Growth reductions and legacy effects were significantly stronger in the third and fourth consecutive dry years than that of single dry year(p<0.05),which might have been due to the cumulative stress caused by consecutive dry years.Our results showed that larch trees experienced greater tree growth reduction due to consecutive dry years and their legacy effect,and the trees had lower recovery rates after consecutive dry years.Our results highlight that consecutive dry years pose a new threat to plantations under climate warming,and thus,the effect of climate extremes on tree growth should be considered in growth models in semiarid areas.
文摘The physiological effect of new FA antitranspirant on winter wheat was studied by field trial. The new FA antitranspirant was sprayed at ear filling stage, using the following concentrations： 0.5, 1.0, 1.5 and 2.0 mL L^-1. The results indicated that new FA antitranspirant increased nitrate reductase activity （NRA）, free proline content, chlorophyll content and water content of leaf, thus drought stress can be mitigated. The new FA antitranspirant increased photosynthesis, enlarged stomatal conductance and reduced transpiration rate, thus led to growth stimulation and water loss reduction. New FA antitranspirant caused an increase of grain yield by 7.2%, under the optimal concentration 1.5 mL L^-1.
文摘The field trial was conducted to study physiological effect of new FA antitranspirant on maize. The new FA antitranspirant was sprayed at 10 d pre-tasseling, ear filling stage and 10 d pre-tasseling + ear filling stage, with the concentrations of 0, 0.5, 1.0, 1.5 and 2.0 ml L-1. The results indicated that the application of new FA antitranspirant increased nitrate reductase activity(NRA), free proline content, chlorophyll content and water content of leaf, thus drought stress can be mitigated. The new FA antitranspirant increased photosynthesis rate and reduced transpiration rate, stimulated growth and reduced water loss. 10 d pre-tasseling + ear filling stage application had a cumulative effect on the indices compared with 10 d pre-tasseling and ear filling stage, except for NRA. The new FA antitranspirant caused an increase of grain yield by 5.37 to 29. 58% with different treatments. The optimal concentration is 1. 5 ml L-1, i. e. 75 g new FA antitranspirant dissolved in 50 kg water, and the optimal apply period is 10 d pre-tasseling + ear filling stage.
文摘植被总初级生产力(Gross Primary Productivity,GPP)是陆地生态系统碳汇的重要组成部分。深入理解干旱对植被GPP影响的累积效应和滞后效应,揭示植被响应机制,对云南省生态安全具有重要意义。然而,关于植被GPP干旱响应机制的时空异质性和影响因子的研究仍较为匮乏。研究基于2001—2023年植被GPP和标准化降水蒸散发指数数据,采用时间序列分析方法和最大相关系数法,分析了云南省气象干旱和植被GPP的时空变化特征,量化并探讨了干旱对植被GPP的累积效应与滞后效应,及其受长期干湿状况和海拔的影响。结果表明:(1)近23年以来,云南省总体上表现为不显著干旱化趋势。干旱的高发区域主要分布在西北部、西部和中东部,高发时段为春季和秋季。植被GPP多年均值为1600.2 g C/m^(2),年际变化表现为极显著上升趋势(6.8 g C m^(-2) a^(-1),P<0.001),但年际波动较为明显。(2)植被GPP对干旱的响应具有明显的时空异质性,以秋季和春季响应最为显著,空间上干热河谷地区最易受干旱影响,响应强烈且迅速。(3)全省52.0%和54.9%的区域植被GPP显著受干旱累积效应和滞后效应的影响。累积效应时间尺度以中短期(4—6个月)和长期(10—12个月)为主,滞后时间以长期(10—12个月)为主。相较灌木和森林,农田和草地对干旱的响应更强烈、时间尺度更短。滞后时间在不同植被类型间的差异较小。(4)长期干湿状况和海拔是影响干旱累积效应和滞后效应的重要因素。随着环境从干燥转为湿润或是海拔升高,干旱影响强度会逐渐降低,累积效应时间尺度延长,而滞后时间则缩短。海拔对干旱影响强度的作用大于干湿状况,而累积效应时间尺度和滞后时间受干湿状况的影响则更显著。研究结果可以为干旱风险缓解与应对管理策略的制定提供科学依据。
