陆地生物圈模型如果不考虑低温下量子产率和凸度的降低，可能会高估北极的 CO 同化。

Terrestrial biosphere models may overestimate Arctic CO assimilation if they do not account for decreased quantum yield and convexity at low temperature.

机构信息

Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, 11973-5000, USA.

Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6301, USA.

出版信息

New Phytol. 2019 Jul;223(1):167-179. doi: 10.1111/nph.15750. Epub 2019 Mar 18.

DOI:10.1111/nph.15750

PMID:30767227

Abstract

How terrestrial biosphere models (TBMs) represent leaf photosynthesis and its sensitivity to temperature are two critical components of understanding and predicting the response of the Arctic carbon cycle to global change. We measured the effect of temperature on the response of photosynthesis to irradiance in six Arctic plant species and determined the quantum yield of CO fixation ( ) and the convexity factor (θ). We also determined leaf absorptance (α) from measured reflectance to calculate on an absorbed light basis ( ) and enabled comparison with nine TBMs. The mean was 0.045 mol CO mol absorbed quanta at 25°C and closely agreed with the mean TBM parameterisation (0.044), but as temperature decreased measured diverged from TBMs. At 5°C measured was markedly reduced (0.025) and 60% lower than TBM estimates. The θ also showed a significant reduction between 25°C and 5°C. At 5°C θ was 38% lower than the common model parameterisation of 0.7. These data show that TBMs are not accounting for observed reductions in and θ that can occur at low temperature. Ignoring these reductions in and θ could lead to a marked (45%) overestimation of CO assimilation at subsaturating irradiance and low temperature.

摘要

陆地生物圈模型（TBMs）如何表示叶片光合作用及其对温度的敏感性是理解和预测北极碳循环对全球变化响应的两个关键组成部分。我们测量了温度对六种北极植物物种光合作用对辐照度响应的影响，并确定了 CO2 固定的量子产量（）和凸度因子（θ）。我们还从测量的反射率中确定了叶片吸收率（α），以计算基于吸收光的（），并与九个 TBMs 进行比较。在 25°C 时，平均为 0.045 mol CO/mol 吸收量子，与 TBM 参数化的平均值（0.044）非常吻合，但随着温度降低，测量的值与 TBMs 出现分歧。在 5°C 时，测量的值明显降低（0.025），比 TBM 估计值低 60%。θ也在 25°C 和 5°C 之间显著降低。在 5°C 时，θ比 0.7 的常见模型参数低 38%。这些数据表明，TBMs 没有考虑到在低温下可能发生的和 θ 的观测减少。忽略和 θ 的这些减少可能导致在亚饱和辐照度和低温下 CO2 同化的显著高估（45%）。