引用本文:任小丽,何洪林,张黎,葛蓉,曾纳,李攀,于贵瑞,等.散射辐射对青藏高原高寒草地总初级生产力模拟的影响[J].环境科学研究,2017,30(12):1898-1907.
REN Xiaoli,HE Honglin,ZHANG Li,GE Rong,ZENG Na,LI Pan,YU Guirui,et al.Effects of Diffuse Radiation on Estimation of Gross Primary Production of Alpine Grasslands on the Tibetan Plateau[J].Reserrch of Environmental Science,2017,30(12):1898-1907.]
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散射辐射对青藏高原高寒草地总初级生产力模拟的影响
任小丽1, 何洪林1,2, 张黎1,2, 葛蓉1,2, 曾纳1,2, 李攀3, 于贵瑞1,2
1. 中国科学院地理科学与资源研究所, 生态系统网络观测与模拟重点实验室, 北京 100101;2. 中国科学院大学资源与环境学院, 北京 100190;3. 中国科学院地球化学研究所, 环境地球化学国家重点实验室, 贵州 贵阳 550081
摘要:
太阳辐射的散射组分能够增强植被冠层LUE(light use efficiency,光能利用率),因此需要在生产力模型中显式地加入散射辐射的影响,从而更准确地模拟植被冠层光合作用.以青藏高原高寒草地为研究对象,改进光能利用率模型,增加散射辐射模块,利用站点通量观测数据估计模型关键参数;结合区域尺度气象数据和遥感数据,模拟了2003—2008年青藏高原高寒草地区域尺度GPP(gross primary production,总初级生产力),并量化了GPP模拟的不确定性,进而通过分析模型改进前后GPP空间分布及其不确定性的差异量化了散射辐射的作用.结果表明:考虑散射辐射对LUE的影响后,模型参数优化效果明显提升,青藏高原高寒草地GPP的模拟效果得到提升;2003—2008年青藏高原高寒草地GPP模拟值呈现东南部较大,西北部较小的空间格局,与不考虑散射辐射的结果一致,但GPP平均值由312.3 g/(m2·a)增至341.7 g/(m2·a),增幅约9.4%,说明不考虑散射辐射会低估青藏高原高寒草地GPP;GPP模拟值不确定性的空间分布与不考虑散射辐射的结果一致,但是平均不确定性大小有所降低,从9.15%降至8.66%.研究显示,若在青藏高原高寒草地的GPP模拟中不考虑散射辐射,虽不会影响其空间格局,但会低估GPP模拟值的大小,同时增加其不确定性.
关键词:  散射辐射  光能利用率  总初级生产力  不确定性分析
DOI:10.13198/j.issn.1001-6929.2017.03.23
分类号:X87
基金项目:国家重点研发计划项目(2016YFC0500204);国家自然科学基金项目(41571424);科技基础性工作专项(2015FY110700)
Effects of Diffuse Radiation on Estimation of Gross Primary Production of Alpine Grasslands on the Tibetan Plateau
REN Xiaoli1, HE Honglin1,2, ZHANG Li1,2, GE Rong1,2, ZENG Na1,2, LI Pan3, YU Guirui1,2
1. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;2. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China;3. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
Abstract:
The effects of diffuse radiation on photosynthesis must be incorporated into ecosystem models to accurately simulate gross vegetation photosynthesis, since diffuse radiation can enhance vegetation canopy light use efficiency (LUE). We modified an LUE model to incorporate the effects of diffuse radiation on photosynthesis to simulate the gross primary production (GPP) of alpine grasslands on the Tibetan Plateau during 2003-2008, and quantified the effects of diffuse radiation on the estimation and uncertainty of GPP. Values of key model parameters were estimated using eddy covariance observational data. The results showed that:(1) The performance of the modified model in simulating GPP was improved by considering the impacts of diffuse radiation on LUE, with high correlation between the modeled and observed GPP (R2 > 0.80). (2) Compared to the results without considering diffuse radiation, GPP simulated by the modified model kept the same heterogeneous spatial pattern across the Tibetan Plateau, i. e., higher in the southeast and lower in the northwest. When incorporating the effects of diffuse radiation, the mean annual GPP in Tibetan alpine grasslands increased 9.4%, from 312.3 g/(m2·a) to 341.7 g/(m2·a). (3) The spatial distribution of the uncertainty in GPP was opposite to that of GPP, with larger uncertainty occurring in regions with lower GPP, which was consistent with the results without considering diffuse radiation. The mean uncertainty decreased from 9.15% to 8.66% when diffuse radiation was considered. These results indicated that the magnitude of GPP will be underestimated, and the uncertainty of GPP will be overestimated, if the effects of diffuse radiation are not considered in the LUE model. This emphasizes the importance of diffuse radiation in GPP simulation using the LUE model.
Key words:  diffuse radiation  light use efficiency (LUE)  gross primary production (GPP)  uncertainty analysis