Photosynthesis and water use efficiency in twenty tropical tree species of differing succession status in a Brazilian reforestation

Abstract

Leaf gas exchange characteristics were measured in twenty woody species that differ in succession status ranging from pioneer species (PS) to late succession species (LS) in a Brazilian rain-reforestation ecosystem. Photon-saturated photosynthetic rate, calculated per either a leaf area (P NA) or a dry mass (P NM) basis, differed among species. P NA and P NM were highest in PS and lowest in LS. Variation among species was 3-fold (from 7 to 23 μmol m -2 s -1) for P NA, and 5-fold (from 50 to 275 μmol kg -2 s -1) for P NM. The highest P NA (23 μmol m -2 s -1) and P NM (275 μmol kg -2 s -1) values were recorded in PS Croton urucurana, while the lowest P NA (7 μmol m -2 s -1) and P NM (50 μmol kg -2 s -1) values were recorded in LS Aspidosperma cylindrocarpon. A considerable overlap was recorded between PS and LS in values of stomatal conductance (g s), transpiration rate (E), and leaf mass to area ratio (ALM). However, C. urucurana also showed highest g s and E. P NM was highly correlated with ALM in both PS and LS (r = -0.75 and -0.90, respectively). The high values of instantaneous transpiration efficiency (ITE) and intrinsic water use efficiency (WUE i) were also observed in the PS when compared with the LS.