Differences in phenology between non‐native C4 grasses and native C3 and C4 grasses in a seasonally dry ecosystem

Abstract

Plant species phenology is an important driver of invasions in seasonal climates. The phenology of non‐natives is generally uncoupled from that of native species. Grasses cover a large proportion of the land surface and are important invaders around the world. Interestingly, the phenology of native and non‐native grasses could be modulated by the different metabolic pathways. We aimed to compare the vegetative and reproductive phenology of invasive C₄ grasses with that of coexisting native C₃ and C₄ grasses and to explore the relationship between phenology and climate. We recorded the onset, duration and synchronicity of vegetative and reproductive phenology (flowering and fruiting) during 1 year. Native C₃ grasses had 50% of their above‐ground biomass green earlier and remained in that state for a longer period than non‐native and native C₄ grasses. Flowering and fruiting occurred earlier in non‐native C₄ grasses than in native C₄ grasses. The flowering period was longer in non‐native C₄ than in native C₃ and C₄, with the non‐native Melinis repens (Poaceae), a highly invasive species worldwide, accounting for most of the difference. Non‐native C₄ tended to exhibit a lower flowering and fruiting synchrony than both native C₃ and C₄ species. Finally, reproductive and vegetative phenology was positively associated with temperature, while precipitation was mostly associated with C₄ species. The uncoupled vegetative phenology observed could be related to differences in metabolism among the studied species, while the uncoupled reproduction between non‐native and native C₄ grasses could be due to an advantage in resource use by non‐native species. Our work provides the first insight into the possible role of the species origin and metabolic pathways in the vegetative and reproductive phenology of invasive non‐native C₄ and native C₃ and C₄ grasses. Finally, we suggest future directions to elucidate these processes.