Authors: Stephanie Pau*, Florida State University, Susan Cordell, Institute of Pacific Islands Forestry, Pacific Southwest Research Station, USDA Forest Service, Hilo, Hawai‘i 96720, U.S.A., Rebecca Ostertag, Department of Biology, University of Hawai‘i at Hilo, Hilo, Hawai‘i 96720, U.S.A., Faith Inman-Narahari, Institute of Pacific Islands Forestry, Pacific Southwest Research Station, USDA Forest Service, Hilo, Hawai‘i 96720, U.S.A., Lawren Sack, Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095-1606, U.S.A.
Topics: Biogeography, Earth Science, Environment
Keywords: Hawaii, Hawaiian Islands, biodiversity, tropical forest, climate change
Session Type: Poster
Presentation File: No File Uploaded
Understanding the way tropical tree phenology responds to climate is vital for predicting how climate change may alter ecological functioning of tropical forests. The Hawaiian flora is well studied yet there are few systematic investigations of plant phenology and their abiotic drivers. We examined the effects of temperature, rainfall, and photosynthetically active radiation (PAR) on seed phenology of four dominant species and community-level leaf phenology in a montane wet forest on Hawaiʻi using monthly data collected over ~6 years. We expected that species phenologies would be better explained by variation in temperature and PAR than rainfall because rainfall at this site is not limiting. For three species, including two foundational species in Hawaiian forests (Acacia koa and Metrosideros polymorpha), seed production declined with increasing maximum temperatures, increased with rainfall, and responses to PAR were the most variable across all four species. Community-level leaf phenology decreased with minimum temperatures, increased with rainfall, and showed a peak with PAR ~400 μmol s-1m-2. Our results show that seed and leaf phenology at this site are highly sensitive to climatic variability, with the direction of responses representing favorable or unfavorable conditions for growth and reproduction. Divergent responses to climate change could alter community composition if reproduction or growth declines for some species but not others. How the reproduction and growth of different species will respond to climate change has potential consequences for future shifts in species distributions and the persistence of biodiversity.