The maximum seasonal vegetation photosynthesis (Phomax) is crucial to regulating the global carbon dynamics. Of particular importance are the seasonal increments in vegetation photosynthesis (ΔPho), which provide key insights into understanding Phomax. However, the interannual variability of ΔPho within the photosynthesis‐up period (PUP) and its influencing factors remain unclear. To address this gap, we identified PUP and quantified the multi‐year characteristics of ΔPho using satellite‐derived solar‐induced chlorophyll fluorescence. We further investigated the response of ΔPho in northern ecosystems to climate change and vegetation greening by integrating climate data and the normalized difference vegetation index. In the northern ecosystems, longer PUP often spatially correlated with a higher ΔPho. An increasing trend was evident regarding the multi‐year variations in ΔPho, suggesting enhanced vegetation photosynthesis within the PUP. This phenomenon is primarily driven by increased solar radiation and intensified vegetation greening. Additionally, based on the results derived from satellite data, we found three pieces of evidence for the decoupling trend between vegetation photosynthesis and greening under the influence of climate change: first, the inconsistent trends between ΔPho and greening; second, the declining moving trend in the correlation coefficient between ΔPho and greening, approximately 9.17 × 10−4; and third, the weakened dominant role of greening on ΔPho. These findings were further supported by results from ecosystem model simulations. In summary, this study provides insights into the interannual variability of ΔPho and its influencing factors and indicates that vegetation dynamics and terrestrial carbon cycle are likely to become more complex under future climate change scenarios.

中文翻译：

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光合作用上升期北方生态系统植被光合作用与绿化耦合的下降


最大季节性植被光合作用 （Phomax） 对于调节全球碳动力学至关重要。特别重要的是植被光合作用 （ΔPho） 的季节性增量，这为理解 Phomax 提供了关键见解。然而，ΔPho 在光合作用提升期 （PUP） 内的年际变化及其影响因素仍不清楚。为了解决这一差距，我们鉴定了 PUP 并使用卫星衍生的太阳诱导叶绿素荧光量化了 ΔPho 的多年特征。我们通过整合气候数据和归一化差值植被指数，进一步研究了北方生态系统 ΔPho 对气候变化和植被绿化的响应。在北部生态系统中，较长的 PUP 通常在空间上与较高的 ΔPho 相关。ΔPho 的多年变化呈明显的增加趋势，表明 PUP 内植被光合作用增强。这种现象主要是由于太阳辐射增加和植被绿化加剧造成的。此外，基于卫星数据得出的结果，我们发现了气候变化影响下植被光合作用与绿化脱钩趋势的三个证据：一是 ΔPho 与绿化之间的不一致趋势;其次，ΔPho 与绿化之间相关系数的下降趋势，约为 9.17 × 10−4;第三，绿化对 ΔPho 的主导作用减弱。生态系统模型模拟的结果进一步支持了这些发现。 综上所述，本研究为ΔPho的年际变化及其影响因素提供了见解，并表明在未来气候变化情景下，植被动态和陆地碳循环可能会变得更加复杂。