Early flowering enhances performance among conspecifics

Timing plays a crucial role in plant survival as it determines the environmental conditions during which each phenophase develops. In Mediterranean regions, with high temperatures and low precipitation during summer, the timing of flowering may impact plant performance. Different species avoid harsh abiotic conditions by flowering weeks or months earlier than others. On a shorter time scale, conspecifics that flower just a few days earlier may also gain biotic advantages, such as reduced competition for nutrients or pollinators. We propose that earlier flowering, whether by days for conspecifics or by weeks to months for different species, allows plants to avoid biotic and abiotic stress, respectively, leading to increased reproductive success and growth. We hypothesize that: (i) earlier-flowering species will have higher growth and reproductive success than other species co-occurring in the community, and (ii) earlier-flowering conspecifics will show higher growth and reproductive success than the average of their co-occurring conspecifics. A field study was conducted in SE Spain using 98 co-occurring individuals of four species. We monitored phenology, water loss, and growth over a growing season and estimated relative individual reproduction. Early-flowering species did not show higher relative reproduction than late, co-occurring flowering species, although they differed in water loss. However, early-flowering conspecifics had higher growth and relative reproduction than later-flowering conspecifics, but did not differ in water loss. Our results suggest that early flowering might reduce intraspecific competition among conspecifics, rather than enhance performance of those species that avoid harsh summer conditions (high temperatures and low precipitations).