Abstract Detail


Martin, Claire [1], Neufeld, Howard [2].

Ecophysiological explanations for spatial and temporal variations in autumnal coloration within the canopies of ornamental red maple (Acer rubrum ‘Armstrong’) and Freeman maple (Acer x freemanii)

Some urban red maples (Freeman maples, Acer x freemanii) turn red at the top of the canopy before the bottom, while others turn simultaneously all over (A. rubrum ‘Armstrong’). My research investigated the ecophysiological mechanisms governing spatial and temporal variation in autumnal red coloration in both tree varieties. We compared leaves from the top (8-9 m) and bottom (2 m) of the canopy to see if coloration differences arise from environmental or physiological differences, or both. We used a bucket truck to reach leaves and weather stations to measure microclimates at two heights. Wind speed and solar energy were the only environmental variables that differed between upper and lower leaves. Lower leaves of Freeman maples leafed out first, reached full size ~13 days earlier, and persisted longer (~18 days) into the fall than those from the top, resulting in longer leaf lifespans by ~14 days. Mid-summer chlorophyll content in Freeman maples was higher in lower leaves, and in fall, anthocyanins accumulated earlier in upper leaves, whereas no such differences occurred in Armstrong maples. Photosynthetic rates and nitrogen content were higher in lower leaves of Freeman maples but did not differ in Armstrong maples. Higher photosynthetic rates in Freeman maples correlated with higher chlorophyll and nitrogen contents, while early accumulation of anthocyanins in upper leaves correlated with lower nitrogen content, a factor known to elevate leaf anthocyanin content. Lower nitrogen in upper leaves could be the proximate driver for early anthocyanin synthesis in upper leaves, but we do not know why this difference occurs in Freeman, but not Armstrong maples. The results of this study also provide insight into intra-canopy variation in leaf ecophysiology of open-grown trees in an urban environment, and this may help with future ecophysiological modeling studies.

1 - 497 Old 421 S, Boone, NC, 28607, United States
2 - Appalachian State University, Biology, 572 Rivers St., Boone, NC, 28608, United States

none specified

Presentation Type: Oral Paper
Number: EPH2009
Abstract ID:337
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation

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