Photosynthetic rates of four tree species in the upper canopy of a tropical rain forest at the Pasoh Forest Reserve in Peninsular Malaysia

• Main Authors: Furukawa, Akio, Toma, Takeshi, Maruyama, Yutaka, Matsumoto, Yosuke, Uemura, Akira, Abdullah, Ahmad Makmom, Awang, Muhamad
• Format: Article
• Language: English
• Published: The Japan Society of Tropical Ecology 2001
• Online Access: http://psasir.upm.edu.my/id/eprint/48660/1/Photosynthetic%20rates%20of%20four%20tree%20species%20in%20the%20upper%20canopy%20of%20a%20tropical%20rain%20forest%20at%20the%20Pasoh%20Forest%20Reserve%20in%20Peninsular%20Malaysia.pdf; http://psasir.upm.edu.my/id/eprint/48660/; https://www.jstage.jst.go.jp/article/tropics/10/4/10_4_519/_article

Measurements of photosynthesis (A) and stomatal conductance (gs) were conducted using the leaves of four tropical tree species (Dipterocarpus sublamellatus, Neobalanocarpus heimii, Ptychopyxis caput-medusae, and Xanthophyllum amoneum) in the canopy of the lowland forest at the Pasoh Forest Reserve in peninsular Malaysia. A canopy walkway was used to reach the canopy of 30- to 40-m-tall trees and diurnal changes in A and gs were determined. The diurnal patterns for A differed between days and between species, though A of the four species were similar but quite low. In general, A increased with increasing photosynthetically active radiation (PAR) before noon, then declined. As well, a linear relationship was detected between gs and A, but no statistically significant correlation could be confirmed between these two factors for D. sublamellatus and P. caput-medusae in November and July. The value of gs decreased with increasing vapor pressure deficit for D. sublamellatus, but the other species did not show this response.