Plant material
The most dominant canopy and subcanopy evergreen tree species were
chosen for the study. For each species, individual trees were randomly
selected from within the VCR2 plot. Branches from the same set of
individual trees were sampled during both the seasons. Leaf samples were
collected during two seasons: 1) the hottest and driest period of the
year during October 2017, referred to as ‘end of dry’ period and 2) the
end of the wet season during March–April 2018, referred to as the ‘wet’
period (Supporting Information Figure S1). Plant material was collected
in both seasons from three individuals from each of five commonly
occurring evergreen tree species: Hymenaea courbaril L.
(Fabaceae), Brosimum rubescens Taub. (Moraceae), Amaioua
guianensis Aubl. (Rubiaceae), Cheiloclinium cognatum (Miers)
A.C.Sm. (Celastraceae) and Mouriri apiranga Spruce ex Triana.
(Melastomataceae). Plant material from three individuals of two further
species, Chaetocarpus echinocarpus (Baill.) Ducke (Peraceae) andTetragastris altissima (Aubl.) Swart (Burseraceae), was only
collected in the wet period; and one tree was sampled during the end of
dry period for C. echinocarpus (Supporting Information Table S1).
Among the species studied, H. courbaril is the most dominant
emergent tree with an average height of 29.9±0.9 m. C.
echinocarpus (12.7±0.5 m), T. altissima (11.6±0.5 m), B.
rubescens (10.4±0.6 m) and A. guianensis (9.5±0.3 m) are mid
storey trees while C. cognatum (7.1±0.2 m) and M. apiranga(6.8±0.4 m) being the understorey trees.
Trained climbers harvested sunlit canopy branches of the trees between
07:00 to 08:00 AM. The excised branches were separated into small twigs
and transported to the lab (~35km) in closed Styrofoam
boxes with ice packs. Heat treatment assays were done typically within
12h of branch harvest. Fully expanded mature leaves were sampled in all
cases, but during the end of the dry period campaign, H.
courbaril trees had a new flush of leaves and hence, unavoidably for
this species younger leaves were also sampled.