Manavalan, M.; Thakur, D.; Schaumberger, A.; Bahn, M.; Münzbergova, Z.

Background and Aims: Since the Industrial Revolution, rising atmospheric CO2, warming, and more frequent droughts have significantly impacted ecosystems. While the response of leaf functional traits to these global change factors have been widely studied, reproductive traits remain relatively understudied, despite their key role in the diversification and distribution of flowering plants. Here, we investigated how elevated CO2, warming, drought, and their interactions affect floral, leaf and seed traits in two model grassland species. We also examined how these factors influence trait coordination. Methods: Two perennial herbs, Lotus corniculatus and Crepis capillaris, were sampled from a 10-year climate manipulation experiment. We measured resource economic traits related to organ size, construction cost, and dry matter content in both leaves and flowers, along with seed size and number. Univariate and multivariate analyses were used to assess trait responses, and rank-abundance curves were employed to visualize changes in trait coordination across treatments. Key Results: Floral traits, like leaf traits, exhibit trade-offs among themselves but are largely independent of leaf traits. Trait responses to global change factors were inconsistent across species, with drought being the dominant factor affecting only leaf traits in L. corniculatus and all organ types in C. capillaris. Extreme global change conditions led to stronger trait coordination in L. corniculatus, while C. capillaris showed less coordination. Conclusion: Our results show that floral economic traits, like leaf traits, are responsive to individual and combined effects of global change factors. This highlights their importance in shaping plant strategies under environmental stress and emphasizes the need to better integrate floral traits into the whole-plant economic framework.