Vegetation carbon phenology is a key indicator of vegetation actual photosynthesis activity and regulates terrestrial ecosystem carbon balance. A comprehensive understanding of the structural difference of carbon phenology and greenness phenology is still lacking. This study evaluated the structural difference of vegetation greenness phenology and carbon phenology on 95 eddy covariance flux sites (637 site‐years). Vegetation greenness phenology is extracted from remote sensing vegetation indices (i.e., enhanced vegetation index [EVI] and normalized difference vegetation index [NDVI]) of Moderate Resolution Imaging Spectroradiometer satellites; carbon phenology is extracted from daily gross primary production estimates at flux sites. We found that there exists remarkable asynchronization between vegetation greenness phenology and carbon phenology on the 95 flux sites. Generally, the asynchronization is more prevalent in the withering season, with the bias about 18.7 ± 13.0 days for EVI and about 29.8 ± 14.4 days for NDVI. In comparison, in the green‐up season, the bias is only about −1.6 ± 12.9 days for EVI and −6.0 ± 13.8 days for NDVI. We found that photoperiod is the dominant factor controlling the asynchronization and the decrease of photosynthetic capacity in the withering season, other than photosynthetically active radiation or temperature. Our study also reveals that EVI × PC and NDVI × PC are good proxies of vegetation carbon phenology, where PC is the photoperiod constraint and is quantified as . Using PC in the withering season reduces the bias of EVI from 18.7 ± 13.0 days to −2.4 ± 11.2 days and the bias of NDVI from 29.8 ± 14.4 days to −1.1 ± 12.7 days.

中文翻译：

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光周期解释了植被碳物候与植被绿色物候之间的不同步

植被碳物候学是植被实际光合作用活动的关键指标，并调节陆地生态系统的碳平衡。仍然缺乏对碳物候和绿色物候的结构差异的全面了解。这项研究评估了95个涡动协方差通量位点（637个位年）的植被绿色度物候学和碳素物候学的结构差异。从中分辨率成像光谱仪卫星的遥感植被指数（即增强植被指数[EVI]和归一化差异植被指数[NDVI]）中提取植被绿色物候；碳物候是从通量站点的每日一次总生产估算中提取的。我们发现在95个通量位点上，植被绿度物候与碳物候之间存在显着的不同步。通常，异步在枯萎季节更为普遍，EVI的偏差约为18.7±13.0天，NDVI的偏差约为29.8±14.4天。相比之下，在绿色季节，EVI的偏差仅为-1.6±12.9天，NDVI的偏差仅为-6.0±13.8天。我们发现光周期是控制枯萎季节异步和光合能力下降的主要因素，而不是光合有效辐射或温度。我们的研究还表明，EVI×PC和NDVI×PC是植被碳物候学的良好代表，其中PC是光周期约束，被量化为 异步在枯萎季节更为普遍，EVI的偏差约为18.7±13.0天，NDVI的偏差约为29.8±14.4天。相比之下，在绿色季节，EVI的偏差仅为-1.6±12.9天，NDVI的偏差仅为-6.0±13.8天。我们发现，光周期是控制枯萎季节异步和光合能力下降的主要因素，而不是光合有效辐射或温度。我们的研究还表明，EVI×PC和NDVI×PC是植被碳物候学的良好代表，其中PC是光周期约束，被量化为 异步在枯萎季节更为普遍，EVI的偏差约为18.7±13.0天，NDVI的偏差约为29.8±14.4天。相比之下，在绿色季节，EVI的偏差仅为-1.6±12.9天，NDVI的偏差仅为-6.0±13.8天。我们发现，光周期是控制枯萎季节异步和光合能力下降的主要因素，而不是光合有效辐射或温度。我们的研究还表明，EVI×PC和NDVI×PC是植被碳物候学的良好代表，其中PC是光周期约束，被量化为 我们发现，光周期是控制枯萎季节异步和光合能力下降的主要因素，而不是光合有效辐射或温度。我们的研究还表明，EVI×PC和NDVI×PC是植被碳物候学的良好代表，其中PC是光周期约束，被量化为 我们发现，光周期是控制枯萎季节异步和光合能力下降的主要因素，而不是光合有效辐射或温度。我们的研究还表明，EVI×PC和NDVI×PC是植被碳物候学的良好代表，其中PC是光周期约束，被量化为。在枯萎季节使用PC可将EVI的偏差从18.7±13.0天减少到-2.4±11.2天，将NDVI的偏差从29.8±14.4天减少到-1.1±12.7天。