Carbon dioxide absorption and physiological characteristics of selected tropical lowland tree species for revegetation

Abstract

Biological diversity can make a significant contribution to reducing greenhouse gases in the atmosphere. Trees form an essential part of the functioning of the terrestrial biosphere, especially in the carbon cycle. Yet, tree photosynthesis is far less studied than crop photosynthesis. This research aims to assess CO2 absorption-related physiological characteristics of selected tropical lowland trees that are curated in Cibinong Science Center-Botanical Garden (CSC-BG) Indonesia for revegetation prospecting. CO2 absorption, stomatal conductance, and transpiration were measured using an infrared gas analyzer photosynthesis system. Meanwhile, leaf chlorophyll content was estimated using a SPAD chlorophyll-meter. CO2 absorption rate ranged from 3.42 to 20 μmol m-2 s-1. The highest rate was observed in Teijsmanniodendron bogoriense followed by Tectona grandis (19.67 μmol m-2 s-1). The rate of transpiration ranged from 4.7 μmol m-2 s-1 to 7.82 μmol m-2 s-1. Diospyros discolor was the highest, followed by T. grandis (7.65 μmol m-2 s-1). CO2 absorption and rate of transpiration were positively correlated to stomatal conductance. In contrast, the CO2 absorption and chlorophyll content were very weakly correlated. The stomatal conductance ranged from 0.14 to 0.54 μmol m-2 s-1, with that of T. grandis was the highest, followed by Erythrina crista-galli (0.53 μmol m-2 s-1), whereas the chlorophyll content ranged from 31 up to 78.43 SPAD.