Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series o...Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series of paired-field experiments, we estimated the effects of revegetation types and environmental conditions on SOC stock and vertical distribution after replacement of cropland with poplar(Populus tomentosa) and korshinsk peashrub(Caragana korshinskii) in three climate regions(Chifeng City, Fengning City and Datong City of the ′Beijing-Tianjin Sandstorm Source Control′(BTSSC) program area. The results show that SOC sequestration rate ranges from 0.15 Mg/(ha·yr) to 3.76 Mg/(ha·yr) in the soil layer of 0–100 cm in early stage after cropland afforestation in the BTSSC program area. The SOC accumulation rates are the highest in Fengning for both the two vegetation types. Compared to C. korshinskii, P. tomentosa has greater effects on SOC accumulation in the three climate regions, but significantly greater effect only appears in Datong. The SOC density increases by 20%–111% and 15%–59% for P. tomentosa and 9%–63% and 0–73% for C. korshinskii in the 0–20 cm and 20–100 cm soil layers, respectively. Our results indicate that cropland afforestation not only affects SOC stock in the topsoil, but also has some effects on subsoil carbon. However, the effect of cropland afforestation on SOC accumulation varied with climate regions and revegetation types. Considering the large area of revegetation and relatively high SOC accumulation rate, SOC sequestration in the BTSSC program should contribute significantly to decrease the CO2 concentration in the atmosphere.展开更多
Afforestation and reforestation are effective and ecological ways of mitigating elevated atmospheric carbon dioxide(CO2) concentration and increasing carbon(C) storage in terrestrial ecosystems. In this study, we meas...Afforestation and reforestation are effective and ecological ways of mitigating elevated atmospheric carbon dioxide(CO2) concentration and increasing carbon(C) storage in terrestrial ecosystems. In this study, we measured the above-ground(tree, herbaceous plants and litter) and below-ground(root and soil) C storage in an aspen plantation(Populus davidiana) monoculture(PD), a larch plantation(Larix pincipis-rupprechtii) monoculture(LP), a pine plantation(Pinus tabulaeformis) monoculture(PT), a larch and birch mixed plantation(L. pincipis-rupprechtii and Betula platyphlla mixed)(MLB), and an apricot plantation(Armeniaca sibirica) monoculture(AS) under the Desertification Combating Program in Hebei Province, the northern China. The objective was to assess the effect of afforestation species on ecosystem C pools of different plantation types. Results showed that C storage of LP stand(258.0 Mg/ha) and MLB(163.4 Mg/ha) were significantly higher than the C storage in PD(45.5 Mg/ha), PT(58.9 Mg/ha) and AS(49.4 Mg/ha), respectively. Soil C was the main carbon pool of the ecosystem C storage in the five plantation stands, ranging from 31.4 Mg/ha to 232.5 Mg/ha, which accounted for 69.0%–90.1% of the total ecosystem C storage. The C storage in tree layer was about 5.2%–23.2% of ecosystem C storage. The herbaceous plants and litter layers contained 1.0%–6.0% and 1.5%–3.3% of ecosystem C storage, respectively. Our results suggest that tree species should be incorporated to accurately develop regional C budget of afforestation program, and also imply that substantial differences in ecosystem C stocks among plantation types can facilitate decision making on C management.展开更多
Soil respiration(SR) is the second-largest flux in ecosystem carbon cycling. Due to the large spatio-temporal variability of environmental factors, SR varied among different vegetation types, thereby impeding accurate...Soil respiration(SR) is the second-largest flux in ecosystem carbon cycling. Due to the large spatio-temporal variability of environmental factors, SR varied among different vegetation types, thereby impeding accurate estimation of CO_2 emissions via SR. However, studies on spatio-temporal variation of SR are still scarce for semi-arid regions of North China. In this study, we conducted 12-month SR measurements in six land-use types, including two secondary forests(Populus tomentosa(PT) and Robinia pseudoacacia(RP)), three artificial plantations(Armeniaca sibirica(AS), Punica granatum(PG) and Ziziphus jujuba(ZJ)) and one natural grassland(GR), to quantify spatio-temporal variation of SR and distinguish its controlling factors. Results indicated that SR exhibited distinct seasonal patterns for the six sites. Soil respiration peaked in August 2012 and bottomed in April 2013. The temporal coefficient of variation(CV) of SR for the six sites ranged from 76.98% to 94.08%, while the spatial CV of SR ranged from 20.28% to 72.97% across the 12-month measurement. Soil temperature and soil moisture were the major controlling factors of temporal variation of SR in the six sites, while spatial variation in SR was mainly caused by the differences in soil total nitrogen(STN), soil organic carbon(SOC), net photosynthesis rate, and fine root biomass. Our results show that the annual average SR and Q_(10)(temperature sensitivity of soil respiration) values tended to decrease from secondary forests and grassland to plantations, indicating that the conversion of natural ecosystems to man-made ecosystems may reduce CO_2 emissions and SR temperature sensitivity. Due to the high spatio-temporal variation of SR in our study area, care should be taken when converting secondary forests and grassland to plantations from the point view of accurately quantifying CO_2 emissions via SR at regional scales.展开更多
目的探讨家庭赋权护理对脑肿瘤患者及其家属情绪的影响。方法采用非同期临床对照试验将136例脑肿瘤住院患者及其家属分为对照组和干预组,对照组仅对患者实施一般照护,干预组在此基础上实施家庭赋权护理。使用焦虑自评量表(self-rating a...目的探讨家庭赋权护理对脑肿瘤患者及其家属情绪的影响。方法采用非同期临床对照试验将136例脑肿瘤住院患者及其家属分为对照组和干预组,对照组仅对患者实施一般照护,干预组在此基础上实施家庭赋权护理。使用焦虑自评量表(self-rating anxiety scale,SAS)、抑郁自评量表(self-rating depression scale,SDS)测量患者和家属的负性情绪,使用重危患者家属需求量表(critical care family needs inventory,CCFNI)评估患者家属的需求。结果干预组患者及家属在家庭赋权护理实施后2周、出院时、出院后2个月的SAS、SDS评分显著低于对照组,组间比较差异具有统计学意义(P<0.05);干预组实施干预后患者及家属的SAS、SDS评分显著低于入院时评分,入院前后比较差异具有统计学意义(P<0.05)。结论家庭赋权护理能有效减轻脑肿瘤患者及其家属焦虑抑郁情绪。展开更多
基金Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060600)Knowledge Innovation Programs of Chinese Academy of Sciences(No.KSCX2-EW-J-5)National Key Technology Research and Development Program of China(No.2011BAD31B02)
文摘Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series of paired-field experiments, we estimated the effects of revegetation types and environmental conditions on SOC stock and vertical distribution after replacement of cropland with poplar(Populus tomentosa) and korshinsk peashrub(Caragana korshinskii) in three climate regions(Chifeng City, Fengning City and Datong City of the ′Beijing-Tianjin Sandstorm Source Control′(BTSSC) program area. The results show that SOC sequestration rate ranges from 0.15 Mg/(ha·yr) to 3.76 Mg/(ha·yr) in the soil layer of 0–100 cm in early stage after cropland afforestation in the BTSSC program area. The SOC accumulation rates are the highest in Fengning for both the two vegetation types. Compared to C. korshinskii, P. tomentosa has greater effects on SOC accumulation in the three climate regions, but significantly greater effect only appears in Datong. The SOC density increases by 20%–111% and 15%–59% for P. tomentosa and 9%–63% and 0–73% for C. korshinskii in the 0–20 cm and 20–100 cm soil layers, respectively. Our results indicate that cropland afforestation not only affects SOC stock in the topsoil, but also has some effects on subsoil carbon. However, the effect of cropland afforestation on SOC accumulation varied with climate regions and revegetation types. Considering the large area of revegetation and relatively high SOC accumulation rate, SOC sequestration in the BTSSC program should contribute significantly to decrease the CO2 concentration in the atmosphere.
基金Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060600)Knowledge Innovation Programs of Chinese Academy of Science(No.KSCX2-EW-J-5)
文摘Afforestation and reforestation are effective and ecological ways of mitigating elevated atmospheric carbon dioxide(CO2) concentration and increasing carbon(C) storage in terrestrial ecosystems. In this study, we measured the above-ground(tree, herbaceous plants and litter) and below-ground(root and soil) C storage in an aspen plantation(Populus davidiana) monoculture(PD), a larch plantation(Larix pincipis-rupprechtii) monoculture(LP), a pine plantation(Pinus tabulaeformis) monoculture(PT), a larch and birch mixed plantation(L. pincipis-rupprechtii and Betula platyphlla mixed)(MLB), and an apricot plantation(Armeniaca sibirica) monoculture(AS) under the Desertification Combating Program in Hebei Province, the northern China. The objective was to assess the effect of afforestation species on ecosystem C pools of different plantation types. Results showed that C storage of LP stand(258.0 Mg/ha) and MLB(163.4 Mg/ha) were significantly higher than the C storage in PD(45.5 Mg/ha), PT(58.9 Mg/ha) and AS(49.4 Mg/ha), respectively. Soil C was the main carbon pool of the ecosystem C storage in the five plantation stands, ranging from 31.4 Mg/ha to 232.5 Mg/ha, which accounted for 69.0%–90.1% of the total ecosystem C storage. The C storage in tree layer was about 5.2%–23.2% of ecosystem C storage. The herbaceous plants and litter layers contained 1.0%–6.0% and 1.5%–3.3% of ecosystem C storage, respectively. Our results suggest that tree species should be incorporated to accurately develop regional C budget of afforestation program, and also imply that substantial differences in ecosystem C stocks among plantation types can facilitate decision making on C management.
基金Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060600)National Natural Science Foundation of China(No.51378306)
文摘Soil respiration(SR) is the second-largest flux in ecosystem carbon cycling. Due to the large spatio-temporal variability of environmental factors, SR varied among different vegetation types, thereby impeding accurate estimation of CO_2 emissions via SR. However, studies on spatio-temporal variation of SR are still scarce for semi-arid regions of North China. In this study, we conducted 12-month SR measurements in six land-use types, including two secondary forests(Populus tomentosa(PT) and Robinia pseudoacacia(RP)), three artificial plantations(Armeniaca sibirica(AS), Punica granatum(PG) and Ziziphus jujuba(ZJ)) and one natural grassland(GR), to quantify spatio-temporal variation of SR and distinguish its controlling factors. Results indicated that SR exhibited distinct seasonal patterns for the six sites. Soil respiration peaked in August 2012 and bottomed in April 2013. The temporal coefficient of variation(CV) of SR for the six sites ranged from 76.98% to 94.08%, while the spatial CV of SR ranged from 20.28% to 72.97% across the 12-month measurement. Soil temperature and soil moisture were the major controlling factors of temporal variation of SR in the six sites, while spatial variation in SR was mainly caused by the differences in soil total nitrogen(STN), soil organic carbon(SOC), net photosynthesis rate, and fine root biomass. Our results show that the annual average SR and Q_(10)(temperature sensitivity of soil respiration) values tended to decrease from secondary forests and grassland to plantations, indicating that the conversion of natural ecosystems to man-made ecosystems may reduce CO_2 emissions and SR temperature sensitivity. Due to the high spatio-temporal variation of SR in our study area, care should be taken when converting secondary forests and grassland to plantations from the point view of accurately quantifying CO_2 emissions via SR at regional scales.
文摘目的探讨家庭赋权护理对脑肿瘤患者及其家属情绪的影响。方法采用非同期临床对照试验将136例脑肿瘤住院患者及其家属分为对照组和干预组,对照组仅对患者实施一般照护,干预组在此基础上实施家庭赋权护理。使用焦虑自评量表(self-rating anxiety scale,SAS)、抑郁自评量表(self-rating depression scale,SDS)测量患者和家属的负性情绪,使用重危患者家属需求量表(critical care family needs inventory,CCFNI)评估患者家属的需求。结果干预组患者及家属在家庭赋权护理实施后2周、出院时、出院后2个月的SAS、SDS评分显著低于对照组,组间比较差异具有统计学意义(P<0.05);干预组实施干预后患者及家属的SAS、SDS评分显著低于入院时评分,入院前后比较差异具有统计学意义(P<0.05)。结论家庭赋权护理能有效减轻脑肿瘤患者及其家属焦虑抑郁情绪。
