全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13...全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13)C)和水分利用效率(iWUE)对气候变暖和大气CO2浓度急剧上升的响应缺乏研究。本研究利用天山西部伊犁河流域的雪岭云杉树轮样本,使用树木年代学方法和树轮稳定碳同位素技术,建立树轮宽度年表、稳定碳同位素(δ^(13)C)以及内禀水分利用效率(iWUE)序列,分析了树轮δ13C和iWUE的长期变化特征,探讨了树轮δ13C和iWUE对气候的响应规律以及iWUE与树轮宽度的关系。结果表明,主要的气候因子并没有强烈地限制树木径向生长;夏季平均气温对树轮δ^(13)C分馏有重要影响,iWUE的长期变化受到全球Ca增加和升温趋势影响,但直接影响iWUE年际变化的主要因素是饱和水汽压亏缺(VPD)。全球升温和Ca增加导致了iWUE的持续升高,但并没有导致雪岭云杉树木径向生长的明显增加。展开更多
Abstract：The carbon isotopic composition （δ13C） of tree rings was used to assess changes in intrinsic water-use efficiency （Wi） to increasing atmospheric CO2 and climate change during the period of 1891–2003. F...Abstract：The carbon isotopic composition （δ13C） of tree rings was used to assess changes in intrinsic water-use efficiency （Wi） to increasing atmospheric CO2 and climate change during the period of 1891–2003. Five Qinghai spruce （Picea crassifolia） stands were selected in the Qilian Mountains, growing along a precipitation gradient. All five δ13C were correlated to each other, but two sites （DDS and CLS）, which are far from the main body of the mountains, show relative weak connections to other sites. Although trees at all sites had improved their Wi in response to increasing atmospheric CO2 concentration, spruce growing in the regions far away from the main body of the mountains were less sensitive to improved Wi than those of other sites. Based on the correlation between carbon isotope discrimination （Δ） and Palmer Drought Severity Index （PDSI）, the drought history covering the period of 1891–2003 was reconstructed in the study region. The two most severe drought epochs of the late 1920s and the last decade were caused by reduced precipitation and climate warming, respectively. Our results will be useful in assessing any further spatial climate-related bioclimatic information.展开更多
Plant water use efficiency(WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of foo...Plant water use efficiency(WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions,improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However,when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2assimilation(AN) and transpiration(E); AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position(governing average light interception) in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.展开更多
运用基于Penman-Monteith公式改进得到的模型PML-V2,结合12个FLUXNET站点及其对应的叶面积指数数据,进行蒸散发分离,进而计算并分析内禀水利用率(intrinsic water use efficiency,iWUE)和冠层水利用率(canopy water use efficiency,tWUE...运用基于Penman-Monteith公式改进得到的模型PML-V2,结合12个FLUXNET站点及其对应的叶面积指数数据,进行蒸散发分离,进而计算并分析内禀水利用率(intrinsic water use efficiency,iWUE)和冠层水利用率(canopy water use efficiency,tWUE)的趋势差异.结果表明,在站点尺度上,两种植被水利用率的变化均存在不一致性.对于落叶阔叶林(deciduous broadleaf forests,DBF),iWUE的增幅比tWUE的增幅大,而在常绿针叶林(evergreen needleleaf forests,ENF)中则相反.在DBF中,冠层导度和蒸腾作用趋势的差异可在一定程度上解释两种植被水利用率的趋势差异.通过回归分析发现森林(包括DBF和ENF)的气温和大气CO_(2)浓度的趋势对tWUE趋势的影响更大.研究结果表明,两种植被水利用率及其趋势存在差异.基于iWUE的研究结果并不能完全反映植被的实际水利用率变化程度,因此也不能全面反映植被与大气的相互作用.本文在站点尺度明确了全球气候变化背景下两种植被水利用率的趋势差异,有助于理解陆地生态系统与大气之间的相互作用,为合理有效地预测未来气候变化及陆地植被的演变提供有用的参考依据.展开更多
为了定量研究水分利用效率(water use efficiency,WUE)对CO_(2)浓度的响应,在植物光合作用对CO_(2)响应模型的基础上构建了WUE(分为内禀水分利用效率和瞬时水分利用效率,即WUEi和WUEinst)对CO_(2)(包括大气CO_(2)浓度和胞间CO_(2)浓度,...为了定量研究水分利用效率(water use efficiency,WUE)对CO_(2)浓度的响应,在植物光合作用对CO_(2)响应模型的基础上构建了WUE(分为内禀水分利用效率和瞬时水分利用效率,即WUEi和WUEinst)对CO_(2)(包括大气CO_(2)浓度和胞间CO_(2)浓度,即Ca和Ci)的响应模型,并应用新构建的模型对小麦(Triticum aestivum L.)测量数据进行了拟合。结果表明,新构建的模型不仅可以很好地拟合小麦叶片WUE对CO_(2)浓度的响应曲线(包括WUEi-Ca、WUEi-Ci、WUEinst-Ca和WUEinst-Ci曲线),而且还可以直接给出小麦的最大WUEi和WUEinst以及相对应的饱和Ca和Ci。以小麦WUEi-Ca和WUEinst-Ca曲线拟合结果为例,得到的最大WUEi和WUEinst分别为176.29μmol·mol^(-1)和8.65 mol·mmol^(-1),其对应的观测值分别为172.96μmol·mol^(-1)和8.62 mol·mmol^(-1);拟合得到的饱和CO_(2)浓度分别为1410.52和1399.73μmol·mol^(-1),对应的观测值分别为1294.05和1332.84μmol·mol^(-1)。拟合值与观测值之间均无显著差异。由此可见,新建模型拟合得到的这些参数与观测值高度相符,可用于植物WUE对未来CO_(2)增加响应规律研究。展开更多
文摘全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13)C)和水分利用效率(iWUE)对气候变暖和大气CO2浓度急剧上升的响应缺乏研究。本研究利用天山西部伊犁河流域的雪岭云杉树轮样本,使用树木年代学方法和树轮稳定碳同位素技术,建立树轮宽度年表、稳定碳同位素(δ^(13)C)以及内禀水分利用效率(iWUE)序列,分析了树轮δ13C和iWUE的长期变化特征,探讨了树轮δ13C和iWUE对气候的响应规律以及iWUE与树轮宽度的关系。结果表明,主要的气候因子并没有强烈地限制树木径向生长;夏季平均气温对树轮δ^(13)C分馏有重要影响,iWUE的长期变化受到全球Ca增加和升温趋势影响,但直接影响iWUE年际变化的主要因素是饱和水汽压亏缺(VPD)。全球升温和Ca增加导致了iWUE的持续升高,但并没有导致雪岭云杉树木径向生长的明显增加。
基金supported by the Natural Science foundation in China (Grant No. 40871002,40501076)the Knowledge Innovation Project of the Chinese Academy Sciences (KZCX2-YW-QN308)the Self-determination Project of State Key Laboratory of Cryospheric Sciences (SKLCS09-03)
文摘Abstract：The carbon isotopic composition （δ13C） of tree rings was used to assess changes in intrinsic water-use efficiency （Wi） to increasing atmospheric CO2 and climate change during the period of 1891–2003. Five Qinghai spruce （Picea crassifolia） stands were selected in the Qilian Mountains, growing along a precipitation gradient. All five δ13C were correlated to each other, but two sites （DDS and CLS）, which are far from the main body of the mountains, show relative weak connections to other sites. Although trees at all sites had improved their Wi in response to increasing atmospheric CO2 concentration, spruce growing in the regions far away from the main body of the mountains were less sensitive to improved Wi than those of other sites. Based on the correlation between carbon isotope discrimination （Δ） and Palmer Drought Severity Index （PDSI）, the drought history covering the period of 1891–2003 was reconstructed in the study region. The two most severe drought epochs of the late 1920s and the last decade were caused by reduced precipitation and climate warming, respectively. Our results will be useful in assessing any further spatial climate-related bioclimatic information.
基金financial support from the Spanish Ministry of Science and Technology (project AGL2011-30408-C04-01)from Conselleria de Educación, Cultura y Universidades (Govern de les Illes Balears)the European Social Fund through the ESF Operational Programme for the Balearic Islands 2013–2017 (project PD/027/2013)
文摘Plant water use efficiency(WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions,improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However,when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2assimilation(AN) and transpiration(E); AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position(governing average light interception) in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.
文摘运用基于Penman-Monteith公式改进得到的模型PML-V2,结合12个FLUXNET站点及其对应的叶面积指数数据,进行蒸散发分离,进而计算并分析内禀水利用率(intrinsic water use efficiency,iWUE)和冠层水利用率(canopy water use efficiency,tWUE)的趋势差异.结果表明,在站点尺度上,两种植被水利用率的变化均存在不一致性.对于落叶阔叶林(deciduous broadleaf forests,DBF),iWUE的增幅比tWUE的增幅大,而在常绿针叶林(evergreen needleleaf forests,ENF)中则相反.在DBF中,冠层导度和蒸腾作用趋势的差异可在一定程度上解释两种植被水利用率的趋势差异.通过回归分析发现森林(包括DBF和ENF)的气温和大气CO_(2)浓度的趋势对tWUE趋势的影响更大.研究结果表明,两种植被水利用率及其趋势存在差异.基于iWUE的研究结果并不能完全反映植被的实际水利用率变化程度,因此也不能全面反映植被与大气的相互作用.本文在站点尺度明确了全球气候变化背景下两种植被水利用率的趋势差异,有助于理解陆地生态系统与大气之间的相互作用,为合理有效地预测未来气候变化及陆地植被的演变提供有用的参考依据.
