China’s endeavors to mitigate recurrent crop residue burning(CRB)and improve air quality have yielded positive results owing to recent pollution prevention policies.Nonetheless,persistent challenges remain,particular...China’s endeavors to mitigate recurrent crop residue burning(CRB)and improve air quality have yielded positive results owing to recent pollution prevention policies.Nonetheless,persistent challenges remain,particularly in the Northeast China(NEC),where low temperature complicates crop residue management.Here,we examined the effects of cropping pattern adjustment on variations of CRB patterns in NEC during 2001-2021,utilizing the Moderate-resolution Imaging Spectroradiometer(MODIS)burned area dataset,the Visible Infrared Imaging Radiometer Suite(VIIRS)active fire dataset,and the high-accuracy crop planting area maps.Our results revealed an overall upward trend of 805.96 km^(2)/yr in NEC CRB from 2001 to 2021.The corn CRB area accounted for more than 50%of the total CRB area in each CRB-intensive year(2013-2021),and the increasing corn CRB generally aligns with the growing corn cultivation fields.A seasonal shift in CRB was found around 2017,with intensive CRB activities transitioning from both autumn and spring to primarily spring,particularly in the Songnen Plain and Sanjiang Plain.The changing trend of PM2.5 concentration aligned spatially with the shift.Moreover,the CRBs in spring of 2020 and 2021 were more severe than the major burning seasons in previous years,likely due to the disruptions during COVID-19 lockdowns.In certain years,the explanatory power of spring CRB on PM2.5 concentration was comparable to that of other natural factors,such as precipitation.This study underscores the critical need for sustained and region-specific strategies to tackle the challenges posed by CRBs.展开更多
Background Increasing atmospheric nitrogen(N)deposition is a major threat to plant diversity globally.Recent observations show that the reduced-to-oxidized(NH_(x)/NO_(y))ratio of N deposition has been changing spatial...Background Increasing atmospheric nitrogen(N)deposition is a major threat to plant diversity globally.Recent observations show that the reduced-to-oxidized(NH_(x)/NO_(y))ratio of N deposition has been changing spatially and temporally.How and to what extent different N forms(i.e.,NH_(x)and NO_(y))influence grassland plant species loss are still unclear.Methods We employed a field manipulative experiment by using three N forms[i.e.,Ca(NO_(3))_(2),NH_(4)NO_(3),and(NH_(4))_(2)SO_(4)]with six N addition levels(0,4,8,16,24,32 g N m^(-2)year^(-1))in a temperate grassland and conducted a greenhouse experiment culturing four plant species corresponding different plant functional groups under Ca(NO_(3))_(2)or(NH_(4))_(2)SO_(4)addition.Results Results from our field experiment showed that the plant species loss rate was greater under NH_(4)^(+)-N than NO_(3)^(-)-N enrichment.Plant species loss was driven by light asymmetry under NO_(3)^(-)-N enrichment,while it was co-driven by light asymmetry and soil acidification under NH_(4)NO_(3)enrichment.Under NH_(4)^(+)-N enrichment,light asymmetry,pH decrease,NH_(4)^(+) toxicity,and metal toxicity jointly affected species loss.The greenhouse experiment provided direct evidence that legumes and forbs are more physiologically susceptible to NH_(4)^(+)-induced toxicity than grasses.Conclusions Our results emphasize that N forms play a vital role in affecting grassland plant diversity.This suggests that regions with higher NH_(x) enrichment may experience more severe plant diversity losses as N deposition continues to increase.Therefore,appropriate measures should be adopted to mitigate species losses.展开更多
基金supported by the National Key Research and Devel-opment Program of China(Grant No.2023YFD1500200)the funding project of Northeast Geological S&T Innovation Center of China Geologi-cal Survey(Grant No.QCJJ2022-9)+3 种基金the Strategic Priority Research Pro-gram of the Chinese Academy of Sciences(Grant No.XDA28060100)the Youth Interdisciplinary Team Project of the Chinese Academy of Sciences(JCTD-2021-04)the Informatization Plan of the Chinese Academy of Sciences(Grant No.CAS-WX2021PY-0109)the National Natural Science Foundation of China(Grants No.41971078,42271375,72221002,42001378).
文摘China’s endeavors to mitigate recurrent crop residue burning(CRB)and improve air quality have yielded positive results owing to recent pollution prevention policies.Nonetheless,persistent challenges remain,particularly in the Northeast China(NEC),where low temperature complicates crop residue management.Here,we examined the effects of cropping pattern adjustment on variations of CRB patterns in NEC during 2001-2021,utilizing the Moderate-resolution Imaging Spectroradiometer(MODIS)burned area dataset,the Visible Infrared Imaging Radiometer Suite(VIIRS)active fire dataset,and the high-accuracy crop planting area maps.Our results revealed an overall upward trend of 805.96 km^(2)/yr in NEC CRB from 2001 to 2021.The corn CRB area accounted for more than 50%of the total CRB area in each CRB-intensive year(2013-2021),and the increasing corn CRB generally aligns with the growing corn cultivation fields.A seasonal shift in CRB was found around 2017,with intensive CRB activities transitioning from both autumn and spring to primarily spring,particularly in the Songnen Plain and Sanjiang Plain.The changing trend of PM2.5 concentration aligned spatially with the shift.Moreover,the CRBs in spring of 2020 and 2021 were more severe than the major burning seasons in previous years,likely due to the disruptions during COVID-19 lockdowns.In certain years,the explanatory power of spring CRB on PM2.5 concentration was comparable to that of other natural factors,such as precipitation.This study underscores the critical need for sustained and region-specific strategies to tackle the challenges posed by CRBs.
基金financially supported by the National Natural Science Foundation of China(42203077,32192462)the Chinese Universities Scientific Fund(2020RC009)the 2115 Talent Development Program of China Agricultural University(1201-00109017)
文摘Background Increasing atmospheric nitrogen(N)deposition is a major threat to plant diversity globally.Recent observations show that the reduced-to-oxidized(NH_(x)/NO_(y))ratio of N deposition has been changing spatially and temporally.How and to what extent different N forms(i.e.,NH_(x)and NO_(y))influence grassland plant species loss are still unclear.Methods We employed a field manipulative experiment by using three N forms[i.e.,Ca(NO_(3))_(2),NH_(4)NO_(3),and(NH_(4))_(2)SO_(4)]with six N addition levels(0,4,8,16,24,32 g N m^(-2)year^(-1))in a temperate grassland and conducted a greenhouse experiment culturing four plant species corresponding different plant functional groups under Ca(NO_(3))_(2)or(NH_(4))_(2)SO_(4)addition.Results Results from our field experiment showed that the plant species loss rate was greater under NH_(4)^(+)-N than NO_(3)^(-)-N enrichment.Plant species loss was driven by light asymmetry under NO_(3)^(-)-N enrichment,while it was co-driven by light asymmetry and soil acidification under NH_(4)NO_(3)enrichment.Under NH_(4)^(+)-N enrichment,light asymmetry,pH decrease,NH_(4)^(+) toxicity,and metal toxicity jointly affected species loss.The greenhouse experiment provided direct evidence that legumes and forbs are more physiologically susceptible to NH_(4)^(+)-induced toxicity than grasses.Conclusions Our results emphasize that N forms play a vital role in affecting grassland plant diversity.This suggests that regions with higher NH_(x) enrichment may experience more severe plant diversity losses as N deposition continues to increase.Therefore,appropriate measures should be adopted to mitigate species losses.
