Authors: Grant Elliott*, University of Missouri
Topics: Biogeography, Climatology and Meteorology, Physical Geography
Keywords: autumn climate, biogeography, climate change, eastern forests, oak, phenology
Session Type: Poster
Presentation File: No File Uploaded
Seasonal climate variability drives patterns of tree phenology in temperate deciduous forests across eastern North America, yet it is unclear how species respond to climate extremes, particularly during autumn. This is increasingly important to understand as canopy dominance transitions from oak to maple. In this opportunistic field study, I compare high-resolution measurements of autumn tree phenology across an oak-hickory forest in central Missouri during the warmest autumn on record (2016; 3.1°C above mean) with data from 2017–2018 to test for significant intraspecific and interspecific differences in phenological response. I measured five phenophase levels of leaf color change along ca. 1 km of trails in Rock Bridge State Park for 164 trees, including black oak, chinkapin oak, red oak, white oak, shagbark hickory, and sugar maple. During 2016 there were significantly shorter periods (p < 0.01) of leaf color onset (mean -16.4 ± 4.8 days) and complete leaf color change (-14 days ± 5.4) for all species. Further, duration of peak color was significantly longer (6.8 ± 2.2) in oaks and this phenophase was reached 14–20 days later than maple; no significant differences in peak color measured for hickory or maple. Community-level trends over three years showed that maple transitioned into each autumn phenophase significantly earlier than oaks (4–29 days), irrespective of first autumn frost or climate regime. Results suggest that the ongoing transition to maple canopy dominance could play a stronger role than climate extremes in governing future patterns of autumn tree phenology across oak-hickory forests.