Miaojun Ma, Lanzhou University, discusses his article: Indirect effects of warming via phenology on reproductive success of alpine plants
Background
More and more empirical evidence shows that climate change has altered the reproductive performance of alpine plants, including reproductive phenology and reproductive output. Altered plant phenology can expose species to novel abiotic conditions during growth and modify species interactions, both of which could drive changes in plant reproduction. The loss of potential for sexual reproduction can have long-lasting effects on offspring genetic variability, species demographics, community composition, and many other ecosystem functions. However, little is known about the response of reproductive performance in alpine plants to climate change and its driving mechanisms.
The Tibetan Plateau has experienced more rapid climate warming than the global average, coupled with complex spatiotemporal precipitation variation. Based on a 7-yr field warming and altered precipitation experiment initiated in 2017 in an alpine meadow on the eastern Tibetan Plateau, 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.
Hypotheses
Specifically, we tested two hypotheses; first, we predicted that warming and precipitation reduction decrease the number of flowers by reducing water availability, and further reduce the number of fruits and seeds through cascading effects. Second, we predicted that the response of reproductive phenology explains the effects of warming and precipitation on reproduction because they partly reflect plant resource acquisition ability and reproductive strategy and may differ among functional groups. Finally, we predicted that warming and altered precipitation have different effects on seed number and seed size, because trade-offs between seed number and size are very common.
Key findings
Our results showed that warming advanced the first flowering date of both flowering functional groups, yet the start of fruit setting and ripening of early-spring flowering plants remained stable. The reproduction of early-spring flowering plants was affected by warming, while that of mid-summer flowering plants was affected by warming and altered precipitation. Warming reduced the seed number and seed productivity by changing the reproductive phenology. Decrease in seed numbers in alpine plants was mediated by changes in reproductive phenology and phenological overlap between flowering functional groups under warming and altered precipitation.
Implications
This study emphasizes the important regulatory and indicative role of reproductive phenology in the sexual reproduction of alpine plants under future climate change. Our findings provided new field evidence that phenology mediated the reproductive response of alpine plants to climate change. We found complex linkages among phenology, seed production, and population dynamics, suggesting the necessity of elucidating the full life history for of plants to predict the future dynamics of plant populations and communities under climate change. We would also like to emphasize the importance of changes in timing between different phenological events among flowering functional groups and explore their potential ecological implications.