The semi-arid ecosystems of the African Sahel play an important role in the global carbon cycle and are among the most sensitive ecosystems to future environmental pressures. Still, basic data of photosynthetic characteristics of Sahelian vegetation are very limited, preventing us to properly understand these ecosystems and to project their response to future global changes. Here, we aim to study and quantify key leaf traits, including photosynthetic parameters and leaf nutrients (N_leaf and P_leaf), of common C₃ and C₄ Sahelian plants (trees, lianas, and grasses) at the Dahra field site (Senegal). Dahra is a reference site for grazed semi-arid Sahelian savannah ecosystems in carbon cycle studies. Within the studied species, we found that photosynthetic parameters varied considerably between functional types. We also found significant relationships between and within photosynthetic parameters and leaf traits which mostly differed in their slopes from C₃ to C₄ plants. In agreement with the leaf economic spectrum, strong relationships (R² = 0.71) were found between SLA and N_leaf whereby C₃ and C₄ plants showed very similar relationships. By comparing our data to a global dataset of plant traits, we show that measured Sahelian plants exhibit higher photosynthetic capacity (A_sat) compared to the non-Sahelian vegetation, with values that are on average a fourfold of the global average. Moreover, Sahelian C₃ plants showed photosynthetic nutrient use efficiencies that were on average roughly twice as high as global averages. We interpreted these results as the potential adaptation of Sahelian plants to short growing season lengths via an efficient nutrient allocation to optimize photosynthesis during this period. Our study provides robust estimates of key functional traits, but also traits relationships that will help to calibrate and validate vegetation models over this data-poor region.

非洲萨赫勒地区的半干旱生态系统在全球碳循环中发挥着重要作用，是对未来环境压力最敏感的生态系统之一。尽管如此，萨赫勒植被光合特性的基本数据非常有限，阻碍了我们正确了解这些生态系统并预测它们对未来全球变化的反应。在这里，我们的目标是研究和量化常见 C ₃和 C _{4 的}关键叶片性状，包括光合参数和叶片养分（N_叶和P_叶）达赫拉田地（塞内加尔）的萨赫勒植物（树木、藤本植物和草）。Dahra 是碳循环研究中放牧半干旱萨赫勒大草原生态系统的参考地点。在研究的物种中，我们发现光合参数在功能类型之间差异很大。我们还发现光合参数和叶片性状之间和内部的显着关系，这些性状主要在 C ₃到 C ₄植物的坡度上有所不同。与叶经济谱一致， 在 SLA 和N_叶之间发现了强关系 ( R ² = 0.71)，其中 C ₃和 C ₄植物表现出非常相似的关系。通过将我们的数据与全球植物性状数据集进行比较，我们发现与非萨赫勒植被相比，测量的萨赫勒植物表现出更高的光合能力 ( A _sat )，其值平均是全球平均值的四倍。此外，萨赫勒 C ₃植物的光合养分利用效率平均约为全球平均水平的两倍。我们将这些结果解释为萨赫勒植物通过有效的养分分配来优化这一时期的光合作用，从而潜在地适应了较短的生长季节长度。我们的研究提供了对关键功能性状的可靠估计，还提供了有助于校准和验证该数据贫乏地区的植被模型的性状关系。