Effect of simulated extreme rainfall on the vegetative phenology of perennial and annual herbaceous plants from a Brazilian dry forest

• Published in: Plant biology (Stuttgart, Germany) Germany), 2024-08, Vol.26 (5), p.868-877
• Main Authors: Aguiar, B. A. de S., Lopes, C. G. R., Sousa, G. M., Medeiros, M. J. L., Silva, K. A., Araújo, E. de L.
• Format: Article
• Language: English
• Subjects: Abscission; Annual precipitation; Annual rainfall; Brazil; Change detection; Climate Change; Climate prediction; Drought; Droughts; Dry forests; Extreme drought; Extreme weather; Forests; leaf emergence; Leaves; Plant growth; Plant Leaves - growth & development; Plant Leaves - physiology; Plants (botany); Precipitation; Rain; Rainfall; Rainy season; Seasons; senescence; Species; Statistical analysis; Tropical forests; Water availability; water stress
• ISSN: 1435-8603; 1438-8677; 1438-8677
• DOI: 10.1111/plb.13674

Detecting changes in the phenological responses of herbaceous species as a function of predicted climate change is important for forecasting future scenarios for the functioning of dry tropical forests, especially when predicting an increase in the frequency and intensity of extreme droughts. Because of the sensitivity of plants to water availability, our study hypothesizes that if years become drier or wetter, herbaceous plants will synchronously change the onset, duration, and intensity of their vegetative phenophases. We used a historical series of 60 years of precipitation observations for the Caatinga vegetation to define daily average of precipitation for rainy (Twet), median (Tcontrol), and dry (Tdry) years. We simulated past average daily rainfall (Twet, Tcontrol, and Tdry) while growing two herbaceous perennials and two herbaceous annuals. We monitored plant growth and measured the activity (absence or presence) and intensity of vegetative phenophases. We used circular statistical analysis to assess differences between treatments. Our results revealed that leaf production was seasonal but relatively uniform for perennial species and highly seasonal (wet season) for annual species. Simulated dry years induced lower leaf emergence concentrated over a few months in annual species, but this effect was more strongly significant in one of the two perennial species. Both annual and perennial species can experience delayed and less intense leaf abscission during the rainy season in years with below‐average precipitation. In contrast, large voluminous rains in years with above‐average precipitation can accelerate and intensify the process of leaf renewal. If future precipitation reductions occur, the changes in phenological response indicate that the cover of annual and perennial herbaceous species in this study will likely decrease, altering the landscape and functioning of dry tropical forests. However, the potential trade‐offs observed may help populations of these species to persist during years of severe drought in the Caatinga. We investigate how extreme rainfall simulations impact the growth cycles of perennial and annual herbaceous species from a Brazilian dry forest.