As a powerful approach,the advantage of usig remote sensing to estimate and supervise net primary productivity of terrestrial vegetation lies not only in that it is free from a lot of trivially detailed field works,bu...As a powerful approach,the advantage of usig remote sensing to estimate and supervise net primary productivity of terrestrial vegetation lies not only in that it is free from a lot of trivially detailed field works,but also in that it realizes the estimation of NPP in a large region.So it largely pushes forward global change research.According to this kind of approach,this paper mainly discusses on the role of vegetation index,PAR and light energy efficiency on the estimation of NPP,and puts forward a few suggestions on improving the NPP models.展开更多
Knowledge of seasonal variation of net ecosystem CO2 exchange (NEE) and its biotic and abiotic controllers will further our understanding of carbon cycling process, mechanism and large-scale modelling. Eddy covariance...Knowledge of seasonal variation of net ecosystem CO2 exchange (NEE) and its biotic and abiotic controllers will further our understanding of carbon cycling process, mechanism and large-scale modelling. Eddy covariance technique was used to measure NEE, biotic and abiotic factors for nearly 3 years in the hinterland alpine steppe--Korbresia meadow grassland on the Tibetan Plateau, the present highest fluxnet station in the world. The main objectives are to investigate dynamics of NEE and its components and to determine the major controlling factors. Maximum carbon assimilation took place in August and maximum carbon loss occurred in November. In June, rainfall amount due to monsoon climate played a great role in grass greening and consequently influenced interannual variation of ecosystem carbon gain. From July through September, monthly NEE presented net carbon assimilation. In other months, ecosystem exhibited carbon loss. In growing season, daytime NEE was mainly controlled by photosynthetically active radiation (PAR). In addition, leaf area index (LAI) interacted with PAR and together modulated NEE rates. Ecosystem respiration was controlled mainly by soil temperature and simultaneously by soil moisture. Q10 was negatively correlated with soil temperature but positively correlated with soil moisture. Large daily range of air temperature is not necessary to enhance carbon gain. Standard respiration rate at referenced 10℃(R10) was positively correlated with soil moisture, soil temperature, LAI and aboveground biomass. Rainfall patterns in growing season markedly influenced soil moisture and therefore soil moisture controlled seasonal change of ecosystem respiration. Pulse rainfall in the beginning and at the end of growing season induced great ecosystem respiration and consequently a great amount of carbon was lost. Short growing season and relative low temperature restrained alpine grass vegetation development. The results suggested that LAI be usually in a low level and carbon uptake be relatively low. Rainf展开更多
该文以中国冬小麦主要种植区黄淮海平原典型县市的冬小麦为研究对象,以植物净初级生产力模型对冬小麦估产进行研究。其中光合有效辐射数据(PAR)主要通过TOM S传感器紫外反射率月数据来计算获得。并且通过投影转换和内插方法,将分辨率由...该文以中国冬小麦主要种植区黄淮海平原典型县市的冬小麦为研究对象,以植物净初级生产力模型对冬小麦估产进行研究。其中光合有效辐射数据(PAR)主要通过TOM S传感器紫外反射率月数据来计算获得。并且通过投影转换和内插方法,将分辨率由经度1.25度、纬度1度转为250 m。光合有效辐射分量(f PAR)主要通过250 m分辨率M OD IS的最大值合成法生成的N DV I月数据和f PAR之间的统计直线关系(f PAR=a N DV I+b)来反演。在研究中光能转化有机质效率(ε)被视为常数,其值通过前人研究结果确定。然后计算冬小麦净初级生产力(N P P=ε×f PAR×PAR)。文中主要考虑冬小麦产量形成关键期内N P P的形成,然后将累积的N P P转化为作物干物质的量,最后通过冬小麦收获指数修正,得到估计的冬小麦产量。而且利用地面实际调查产量数据对所预测的植物净初级生产力N P P和所预测的产量进行了验证,通过N P P计算的冬小麦生物量与实际生物量间相对误差为-4.30%;预测冬小麦产量与实际小麦产量间相对误差平均为-4.41%,结果令人满意。展开更多
光合有效辐射(Photo-synthetically Active Radiation,PAR)是研究全球变化与陆地生态系统变化的核心之一,不仅是衡量生态系统光合作用变化、碳收支变化的重要数据来源,也是反映全球气候变化主要驱动因子。本文在回顾PAR估算方法的基础上...光合有效辐射(Photo-synthetically Active Radiation,PAR)是研究全球变化与陆地生态系统变化的核心之一,不仅是衡量生态系统光合作用变化、碳收支变化的重要数据来源,也是反映全球气候变化主要驱动因子。本文在回顾PAR估算方法的基础上,综合分析了传统方法中的气候学方法、模型参数方法,及在此基础上发展起来的基于遥感的转换系数、模型化参数法的优缺点,并对PAR估算方法研究做出了展望。气候学法、模型参数法等传统方法一直是进行PAR估算的常用手段。然而,随着对生态系统研究的日益深入,基于遥感的估算方法已经成为一种新的手段,凭借遥感覆盖范围广的优势,它使得获取区域乃至全球PAR估算成为可能。因此,如何利用遥感数据获取长时间序列PAR,成为目前关注的重点之一。已有研究表明,查找表方法之类的定量化估算方法将成为主要的估算方法,它不仅在机理上解释了PAR的传输过程,而且增强了估算方法的可靠性、可操作性与普适性。展开更多
以杏树为试材，为了解杏树冠层内透光率随树龄和叶面积指数的变化，采用LP-80型冠层分析仪测定了光合有效辐射PAR（Photosynthetically Active Radiation）在不同树龄杏树冠层三维空间上的分布情况，研究了杏树冠层内透光率随树龄（2-6...以杏树为试材，为了解杏树冠层内透光率随树龄和叶面积指数的变化，采用LP-80型冠层分析仪测定了光合有效辐射PAR（Photosynthetically Active Radiation）在不同树龄杏树冠层三维空间上的分布情况，研究了杏树冠层内透光率随树龄（2-6a）和叶面积指数的变化。结果表明，杏树冠层内部平均PAR的垂直分布具有随着向下累计叶面积指数的增加而递减的趋势，在冠层中上部，透光率较高，PAR递减很明显，冠层下部则维持较低水平，变化不大，在相同的天气和时间条件下不同树龄冠层内PAR同一相对高度的透光率有随树龄增加而递减的趋势，但在不同时刻不同天气条件下，即使同一棵树相同高度同一方位冠层内也具有不同的消光系数，影响杏树冠内光分布的因素是多样的，它们之间存在着复杂的关系；2～6年生杏树冠层中部的全天平均透光率分别为49．5％、30．0％、27．5％、13．4％和7．8％，冠层下部的平均透光率分别为29．1％、12．1％、10．9％、6．4％和5．9％；杏树冠层叶面积指数LAI（kaf Area Index）与透光率呈极显著指数相关关系，其表达式为Y=131．39e^-0．8963X（R^2=0．907^＊＊）；试验结果也可为果树冠层内PAR三维空间分布的模拟研究及冠层结构的优化提供试验方法和理论验证上的参考。展开更多
研究利用基于冠层辐射传输与植物生理过程的MAESTRA模型,结合中国东部鼎湖山、千烟洲及长白山3个典型森林生态系统的CO2通量观测数据,对光合有效辐射（Photosynthetically Active Radiation,PAR）总量及其散射辐射比例变化影响下生态系...研究利用基于冠层辐射传输与植物生理过程的MAESTRA模型,结合中国东部鼎湖山、千烟洲及长白山3个典型森林生态系统的CO2通量观测数据,对光合有效辐射（Photosynthetically Active Radiation,PAR）总量及其散射辐射比例变化影响下生态系统总初级生产力（Gross Primary Productivity,GPP）的变化进行了模拟与敏感性分析,从而探讨这两者的变化对森林生态系统GPP的综合影响。研究结果表明：PAR总量变化对GPP的影响程度由PAR总量变化幅度以及GPP对PAR总量变化的敏感程度所决定,较低的PAR总量与较高的温度条件下GPP对PAR总量变化较敏感;散射辐射比例增大可以提高森林冠层对入射PAR的吸收和利用效率,其对GPP的影响程度由散射辐射量的变化以及散射辐射与直射辐射在吸收与利用效率上的差别所决定,较高温度与叶面积条件下该差别较大;PAR总量与散射辐射比例共同变化对GPP的综合影响取决于上述两个过程的抵消结果,入射PAR较强时两者抵消作用通常更明显,在全年总量上,散射辐射比例变化对GPP的影响能抵消PAR总量变化影响的1/3~1/2。展开更多
文摘As a powerful approach,the advantage of usig remote sensing to estimate and supervise net primary productivity of terrestrial vegetation lies not only in that it is free from a lot of trivially detailed field works,but also in that it realizes the estimation of NPP in a large region.So it largely pushes forward global change research.According to this kind of approach,this paper mainly discusses on the role of vegetation index,PAR and light energy efficiency on the estimation of NPP,and puts forward a few suggestions on improving the NPP models.
基金This study was performed under the auspice of the National Key Project for Basic Research (Grant No. 2002CB412501) the National Natural Science Foundation of China (Grant no. 30470280)+1 种基金 Knowledge Innovation Program of Chinese Academy of Sciences (KZCX3-SW-339)Damxung Grassland Station of Tibetan Autonomous Region provided observation site and person-nel. Special thanks are extended to Mr Guo Wanjun, Suo- lang Ciren, Huang Qingyi and Yang Junping for their help in data collecting.
文摘Knowledge of seasonal variation of net ecosystem CO2 exchange (NEE) and its biotic and abiotic controllers will further our understanding of carbon cycling process, mechanism and large-scale modelling. Eddy covariance technique was used to measure NEE, biotic and abiotic factors for nearly 3 years in the hinterland alpine steppe--Korbresia meadow grassland on the Tibetan Plateau, the present highest fluxnet station in the world. The main objectives are to investigate dynamics of NEE and its components and to determine the major controlling factors. Maximum carbon assimilation took place in August and maximum carbon loss occurred in November. In June, rainfall amount due to monsoon climate played a great role in grass greening and consequently influenced interannual variation of ecosystem carbon gain. From July through September, monthly NEE presented net carbon assimilation. In other months, ecosystem exhibited carbon loss. In growing season, daytime NEE was mainly controlled by photosynthetically active radiation (PAR). In addition, leaf area index (LAI) interacted with PAR and together modulated NEE rates. Ecosystem respiration was controlled mainly by soil temperature and simultaneously by soil moisture. Q10 was negatively correlated with soil temperature but positively correlated with soil moisture. Large daily range of air temperature is not necessary to enhance carbon gain. Standard respiration rate at referenced 10℃(R10) was positively correlated with soil moisture, soil temperature, LAI and aboveground biomass. Rainfall patterns in growing season markedly influenced soil moisture and therefore soil moisture controlled seasonal change of ecosystem respiration. Pulse rainfall in the beginning and at the end of growing season induced great ecosystem respiration and consequently a great amount of carbon was lost. Short growing season and relative low temperature restrained alpine grass vegetation development. The results suggested that LAI be usually in a low level and carbon uptake be relatively low. Rainf
文摘该文以中国冬小麦主要种植区黄淮海平原典型县市的冬小麦为研究对象,以植物净初级生产力模型对冬小麦估产进行研究。其中光合有效辐射数据(PAR)主要通过TOM S传感器紫外反射率月数据来计算获得。并且通过投影转换和内插方法,将分辨率由经度1.25度、纬度1度转为250 m。光合有效辐射分量(f PAR)主要通过250 m分辨率M OD IS的最大值合成法生成的N DV I月数据和f PAR之间的统计直线关系(f PAR=a N DV I+b)来反演。在研究中光能转化有机质效率(ε)被视为常数,其值通过前人研究结果确定。然后计算冬小麦净初级生产力(N P P=ε×f PAR×PAR)。文中主要考虑冬小麦产量形成关键期内N P P的形成,然后将累积的N P P转化为作物干物质的量,最后通过冬小麦收获指数修正,得到估计的冬小麦产量。而且利用地面实际调查产量数据对所预测的植物净初级生产力N P P和所预测的产量进行了验证,通过N P P计算的冬小麦生物量与实际生物量间相对误差为-4.30%;预测冬小麦产量与实际小麦产量间相对误差平均为-4.41%,结果令人满意。
文摘光合有效辐射(Photo-synthetically Active Radiation,PAR)是研究全球变化与陆地生态系统变化的核心之一,不仅是衡量生态系统光合作用变化、碳收支变化的重要数据来源,也是反映全球气候变化主要驱动因子。本文在回顾PAR估算方法的基础上,综合分析了传统方法中的气候学方法、模型参数方法,及在此基础上发展起来的基于遥感的转换系数、模型化参数法的优缺点,并对PAR估算方法研究做出了展望。气候学法、模型参数法等传统方法一直是进行PAR估算的常用手段。然而,随着对生态系统研究的日益深入,基于遥感的估算方法已经成为一种新的手段,凭借遥感覆盖范围广的优势,它使得获取区域乃至全球PAR估算成为可能。因此,如何利用遥感数据获取长时间序列PAR,成为目前关注的重点之一。已有研究表明,查找表方法之类的定量化估算方法将成为主要的估算方法,它不仅在机理上解释了PAR的传输过程,而且增强了估算方法的可靠性、可操作性与普适性。
文摘以杏树为试材，为了解杏树冠层内透光率随树龄和叶面积指数的变化，采用LP-80型冠层分析仪测定了光合有效辐射PAR（Photosynthetically Active Radiation）在不同树龄杏树冠层三维空间上的分布情况，研究了杏树冠层内透光率随树龄（2-6a）和叶面积指数的变化。结果表明，杏树冠层内部平均PAR的垂直分布具有随着向下累计叶面积指数的增加而递减的趋势，在冠层中上部，透光率较高，PAR递减很明显，冠层下部则维持较低水平，变化不大，在相同的天气和时间条件下不同树龄冠层内PAR同一相对高度的透光率有随树龄增加而递减的趋势，但在不同时刻不同天气条件下，即使同一棵树相同高度同一方位冠层内也具有不同的消光系数，影响杏树冠内光分布的因素是多样的，它们之间存在着复杂的关系；2～6年生杏树冠层中部的全天平均透光率分别为49．5％、30．0％、27．5％、13．4％和7．8％，冠层下部的平均透光率分别为29．1％、12．1％、10．9％、6．4％和5．9％；杏树冠层叶面积指数LAI（kaf Area Index）与透光率呈极显著指数相关关系，其表达式为Y=131．39e^-0．8963X（R^2=0．907^＊＊）；试验结果也可为果树冠层内PAR三维空间分布的模拟研究及冠层结构的优化提供试验方法和理论验证上的参考。
文摘研究利用基于冠层辐射传输与植物生理过程的MAESTRA模型,结合中国东部鼎湖山、千烟洲及长白山3个典型森林生态系统的CO2通量观测数据,对光合有效辐射（Photosynthetically Active Radiation,PAR）总量及其散射辐射比例变化影响下生态系统总初级生产力（Gross Primary Productivity,GPP）的变化进行了模拟与敏感性分析,从而探讨这两者的变化对森林生态系统GPP的综合影响。研究结果表明：PAR总量变化对GPP的影响程度由PAR总量变化幅度以及GPP对PAR总量变化的敏感程度所决定,较低的PAR总量与较高的温度条件下GPP对PAR总量变化较敏感;散射辐射比例增大可以提高森林冠层对入射PAR的吸收和利用效率,其对GPP的影响程度由散射辐射量的变化以及散射辐射与直射辐射在吸收与利用效率上的差别所决定,较高温度与叶面积条件下该差别较大;PAR总量与散射辐射比例共同变化对GPP的综合影响取决于上述两个过程的抵消结果,入射PAR较强时两者抵消作用通常更明显,在全年总量上,散射辐射比例变化对GPP的影响能抵消PAR总量变化影响的1/3~1/2。
