Seasonal and drought‐related changes in leaf area profiles depend on height and light environment in an Amazon forest. Issue 3 (9th March 2019)

• Record Type: Journal Article
• Authors: Smith, Marielle N.; Stark, Scott C.; Taylor, Tyeen C.; Ferreira, Mauricio L.; de Oliveira, Eronaldo; Restrepo‐Coupe, Natalia; Chen, Shuli; Woodcock, Tara; dos Santos, Darlisson Bentes; Alves, Luciana F.; Figueira, Michela; de Camargo, Plinio B.; de Oliveira, Raimundo C.; Aragão, Luiz E. O. C.; Falk, Donald A.; McMahon, Sean M.; Huxman, Travis E.; Saleska, Scott R.
• Is Part Of: New phytologist. Volume 222:Issue 3(2019)
• Page Start: 1284
• Page End: 1297
• Publication Date: 2019-03-09
• Subjects: Amazon forest -- climate change -- El Niño drought -- forest canopy structure -- leaf area -- LiDAR remote sensing -- phenology; Botany -- Periodicals; 580
• DOI: 10.1111/nph.15726
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Seasonal dynamics in the vertical distribution of leaf area index (LAI) may impact the seasonality of forest productivity in Amazonian forests. However, until recently, fine‐scale observations critical to revealing ecological mechanisms underlying these changes have been lacking. To investigate fine‐scale variation in leaf area with seasonality and drought we conducted monthly ground‐based LiDAR surveys over 4 yr at an Amazon forest site. We analysed temporal changes in vertically structured LAI along axes of both canopy height and light environments. Upper canopy LAI increased during the dry season, whereas lower canopy LAI decreased. The low canopy decrease was driven by highly illuminated leaves of smaller trees in gaps. By contrast, understory LAI increased concurrently with the upper canopy. Hence, tree phenological strategies were stratified by height and light environments. Trends were amplified during a 2015–2016 severe El Niño drought. Leaf area low in the canopy exhibited behaviour consistent with water limitation. Leaf loss from short trees in high light during drought may be associated with strategies to tolerate limited access to deep soil water and stressful leaf environments. Vertically and environmentally structured phenological processes suggest a critical role of canopy structural heterogeneity in seasonal changes in Amazon ecosystem function. Abstract : See also the Commentary on this article by Atkins & Agee, 222 : 1165–1166 .