Assessing variability of optimum air temperature for photosynthesis across site-years, sites and biomes and their effects on photosynthesis estimation
Assessing variability of optimum air temperature for photosynthesis across site-years, sites and biomes and their effects on photosynthesis estimation
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DOI：
10.1016/j.agrformet.2020.108277
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发表时间：
2021-03
影响因子：
6.2
通讯作者：
Q. Chang;Xiangming Xiao;R. Doughty;Xiaocui Wu;Wenzhe Jiao;Yuanwei Qin
中科院分区：
文献类型：
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作者：
Q. Chang;Xiangming Xiao;R. Doughty;Xiaocui Wu;Wenzhe Jiao;Yuanwei Qin
植被的总初级生产力(GPP)受气温的影响。生物地球化学模型使用最佳气温(T Opt)参数，该参数来自特定生物组的查询表(T opt−b−LT)。许多研究表明，植物具有适应环境条件随时间变化的能力，这表明生物地球化学模型中的静态T opt−b−LT参数可能不能很好地反映实际的T opt，并在GPP估计中引入不确定性。在这里，我们使用来自涡旋协方差(EC)通量塔站点(GPP EC)(T OPT−b−EC，T OPT−SY−EC，T OPT−S−EC)的全球平均气温数据，以及来自MODIS图像的增强型植被指数(T OPT−b−EVI，T OPT−SY−EVI，T opt−S−EVI)来估计特定生物群、特定地点和特定地点的最佳气温。我们评估了四个T opt参数(T opt−b、T opt−SY、T opt−S和T opt−b−LT)之间的一致性，并评估了它们对基于卫星的全球PP估计的影响。我们发现MODIS EVI的T opt参数与GPP EC的T opt参数具有很好的一致性，这表明EVI可以作为一个变量来估计大空间域上单个像素点的T opt。T opt−b、T opt−SY和T opt−S与T opt−b−LT有显著差异。对于所有土地覆盖类型，使用T OPT−b和T OPT−SY估算的GPP与GPP EC的一致性比使用T OPT−b−LT时更一致。我们使用T opt−SY显著改善了生物多样性的8天和年度全球生产总值估计(从1%提高到34%)，特别是对农田、草原和开阔灌木丛。我们的简单计算表明，当使用我们建议的T opt−SY−EVI而不是使用静态T opt−b−LT时，全球GPP估计/年的差异高达10pgC。我们估计T opt的新方法有可能改进基于卫星模型的GPP估计，这可能导致更好地理解碳-气候相互作用。
Gross primary productivity (GPP) of vegetation is affected by air temperature. Biogeochemical models use the optimum air temperature (T opt) parameter, which comes from biome-specific look-up tables (T opt− b− LT). Many studies have shown that plants have the capacity to adapt to changes in environmental conditions over time, which suggests that the static T opt− b− LT parameters in the biogeochemical models may poorly represent actual T opt and induce uncertainty in GPP estimates. Here, we estimated biome-specific, site-year-specific, and site-specific optimum air temperature using GPP data from eddy covariance (EC) flux tower sites (GPP EC)(T opt− b− EC, T opt− sy− EC, T opt− s− EC), the Enhanced Vegetation Index (EVI) from MODIS images (T opt− b− EVI, T opt− sy− EVI, T opt− s− EVI), and mean daytime air temperature (T DT). We evaluated the consistency among the four T opt parameters (T opt− b, T opt− sy, T opt− s and T opt− b− LT), and assessed how they affect satellite-based GPP estimates. We find that T opt parameters from MODIS EVI agree well with those from GPP EC, which indicates that EVI can be used as a variable to estimate T opt at individual pixels over large spatial domains. T opt− b, T opt− sy, and T opt− s differed significantly from T opt− b− LT. GPP estimates using T opt− b and T opt− sy were more consistent with GPP EC than when using T opt− b− LT for all the land cover types. Our use of T opt− sy substantially improved 8-day and annual GPP estimates across biomess (from 1% to 34%), especially for cropland, grassland, and open shrubland. Our simple calculation shows that global GPP estimates differ by up to 10 Pg C/yr when using our suggested T opt− sy− EVI instead of using the static T opt− b− LT. Our new approach on estimating T opt has the potential to improve estimates of GPP from satellite-based models, which could lead to better understanding of carbon-climate interactions.