Solar-induced chlorophyll fluorescence (SIF) has recently emerged as a promising tool for estimating gross primary production (GPP). To date, there is ongoing debate regarding whether the strong correlations between SIF and GPP persist under dry conditions. Here, we conducted continuous far-red SIF measurements in a semi-arid grassland from 2017 to 2019 to investigate its association with GPP. Our findings revealed strong correlations in the seasonal patterns of SIF and GPP during dry conditions (R2=0.79). After disentangling the effects of photosynthetically active radiation and soil water content, we observed consistent responses to environmental variables in both SIF and GPP under dry conditions. Furthermore, we conducted a dominance analysis to assess the contributions of physiological and non-physiological components to the variations in SIF and GPP. Our results demonstrated a substantial increase in the contributions of physiological components to both SIF (wet: 19.29%; dry: 60.23%) and GPP (wet: 20.89%; dry: 28.38%) during dry conditions, highlighting a shift towards enhanced physiological regulation of SIF and GPP in response to dry conditions. In conclusion, our findings provide valuable insights into the GPP-SIF relationships in semi-arid grasslands under dry conditions. These insights hold the potential to refine and constrain model predictions under climate change.

中文翻译：

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半干旱草原干燥条件下太阳诱导的叶绿素荧光追踪冠层光合作用


太阳诱导的叶绿素荧光（SIF）最近已成为估算总初级生产力（GPP）的有前途的工具。迄今为止，关于 SIF 和 GPP 之间的强相关性是否在干燥条件下持续存在的争论仍在继续。在这里，我们于2017年至2019年在半干旱草原进行了连续的远红SIF测量，以研究其与GPP的关联。我们的研究结果表明，在干燥条件下，SIF 和 GPP 的季节性模式具有很强的相关性（R2=0.79）。在解开光合有效辐射和土壤含水量的影响后，我们观察到干燥条件下 SIF 和 GPP 对环境变量的一致响应。此外，我们进行了显性分析，以评估生理和非生理成分对 SIF 和 GPP 变化的贡献。我们的结果表明，在干燥条件下，生理成分对 SIF（湿：19.29%；干：60.23%）和 GPP（湿：20.89%；干：28.38%）的贡献大幅增加，凸显了向增强生理调节的转变SIF 和 GPP 对干燥条件的响应。总之，我们的研究结果为干旱条件下半干旱草原的 GPP-SIF 关系提供了有价值的见解。这些见解有可能完善和限制气候变化下的模型预测。