Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, United Kingdom.
Leverhulme Centre for Nature Recovery, University of Oxford, Oxford, UK.
Nat Commun. 2024 Nov 6;15(1):9574. doi: 10.1038/s41467-024-53949-0.
Tropical forests dominate terrestrial photosynthesis, yet there are major contradictions in our understanding due to a lack of field studies, especially outside the tropical Americas. A recent field study indicated that West African forests have among the highest forests gross primary productivity (GPP) yet observed, contradicting models that rank them lower than Amazonian forests. Here, we show possible reasons for this data-model mismatch. We found that biometric GPP measurements are on average 56.3% higher than multiple global GPP products at the study sites. The underestimation of GPP largely disappears when a standard photosynthesis model is informed by local field-measured values of (a) fractional absorbed photosynthetic radiation (fAPAR), and (b) photosynthetic traits. Remote sensing products systematically underestimate fAPAR (33.9% on average at study sites) due to cloud contamination issues. The study highlights the potential widespread underestimation of tropical forests GPP and carbon cycling and hints at the ways forward for model and input data improvement.
热带森林主导着陆地光合作用，但由于缺乏实地研究，特别是在热带美洲以外地区，我们对其的理解存在很大的矛盾。最近的一项实地研究表明，西非森林的总初级生产力（GPP）是迄今为止观察到的最高的，这与将其排名低于亚马逊森林的模型相矛盾。在这里，我们展示了造成这种数据-模型不匹配的可能原因。我们发现，在研究地点，生物计量 GPP 测量值比多个全球 GPP 产品平均高出 56.3%。当一个标准的光合作用模型由（a）分数吸收光合辐射（fAPAR）和（b）光合作用特征的本地现场测量值来告知时，GPP 的低估在很大程度上消失了。由于云污染问题，遥感产品系统地低估了 fAPAR（在研究地点平均为 33.9%）。该研究强调了对热带森林 GPP 和碳循环的广泛低估的可能性，并暗示了模型和输入数据改进的方法。
