Drought stress and dominant removal: effects on reproductive allocation
There were clear differences in the RA patterns between species, as estimated by their mean and their stability over the years (Fig. 1). These patterns cannot be explained by the competitive dominance of species alone. Even subordinate species differ. Reproductive allocation was on average lower for C. canescens and C. elata at permanently low water level and with inter-annual water treatment, indicating a higher relative investment in non-reproductive biomass (Fig. 1a). After dominant removal, C. canescens produced relatively less flowering ramets in the high water treatment (control), but allocated more to flowering ramets in both drought stress treatments. No mean RA response to either drought stress or dominant removal was observed for the other two subordinate species (C. elongata and D. cespitosa ). For these species, RA showed a non-significant trend suggesting an interaction with dominant removal, increasing under high water conditions and decreasing under low water conditions (Fig. 1a).
Stability of RA over time decreased with permanent drought treatment forC. canescens and C. elongata , whereas C. elata showed no response (Fig. 1b). D. cespitosa was the only species with significant interactions between dominant removal and water treatments. When the dominant species was removed, its RA was more stable in high water, but less stable in permanent low water. With inter-annual water treatment, stability decreased significantly only forC. elongata , indicating increased year-to-year variation in RA.