Indirect effects of warming via phenology on reproductive success of alpine plants

Abstract

Climate warming has induced pronounced shifts in the phenology of alpine plants worldwide, yet the impact of these changes on plant reproduction remains unclear, although phenology plays a vital role in reproduction. Based on a 7‐year field warming and altered precipitation experiment initiated in 2017, we measured three reproductive phenological events and seven reproductive traits of six dominant species, belonging to two flowering functional groups, to assess the effects of climate change on reproductive phenology and the reproductive consequence of changing the phenology in an alpine meadow on the eastern Tibetan Plateau from 2021 to 2023. Warming significantly advanced the start of flowering in early‐spring flowering (ESF) and mid‐summer flowering (MSF) plants, while the fruiting period of ESF plants remained stable. Furthermore, warming led to a decrease in the number of seeds and productivity of alpine plants, while seed size remained stable. Phenological changes regulate the reproductive success of alpine plants. Specifically, the start of flowering for ESF plants and the start of fruiting for MSF plants regulated the number of seeds and productivity of the two flowering functional groups, respectively. The increase in phenological niche overlap and intensification of interspecific competition, caused by different phenological responses of the flowering functional groups to warming, also are key factors contributing to the decline in seed production of alpine plants. Synthesis. These results demonstrate that the reproductive success of alpine plants would be decreased by earlier reproduction under climate warming, and alpine plants tend to maintain stable seed size in response to climate change. Our study emphasizes the important regulatory and indicative role of reproductive phenology in the sexual reproduction of alpine plants under future climate change.