Discussion
Our experimental evaluation of the multiple resource limitation model confirmed that the reproductive allocation patterns of species strongly depend on both light limitation (dominant removal) and the level of belowground water resources. This observation provides empirical support for the evolutionary importance of interactions between above- and belowground resource levels for variation in reproductive investment in clonal plants (Herben et al. 2015; Tonnabel et al. 2017). The heritability and potential for further evolution of the proportion of flowering ramets in clonal plants has previously been supported (Kleunen et al. 2002; De Kort et al. 2020). The adaptive role of plasticity in reproductive allocation under stress conditions has also been demonstrated (Santos-del-Blanco et al. 2013). This contrasts with the non-adaptive null hypothesis for resource matching in flowering. The resource matching assumes a constant allocation of a proportional fraction of annual resources to both seed reproduction and vegetative growth, and that species reproductive allocation does not change with resource level (Kelly & Sork 2002; Pearse et al. 2016; Bogdziewicz et al. 2020). Consistent with our expectations of species reproductive trade-offs in the herbaceous community, we found that the competitively dominant species require more belowground resources for seed reproduction, while competitively weaker subordinate species can reproduce at lower resource levels (Fig. 1a).