Photosynthesis and water use efficiency in twenty tropical tree species of differing successional status in a Brazilian reforestation
Carlos
Alberto
Martinez, USP/RP/FFCLRP/Departamento de Biologia, carlosamh@ffclrp.usp.br
(Presenting)
Anselmo
Nogueira, USP/RP/FFCLRP/Departamento de Biologia, anselmo_bio@bol.com.br
Leonnardo
Lopes
Ferreira, UFSCar/Departamento de Botânica, leonnardo@lycos.co.uk
Carlos
Henrique
Prado, UFSCar/Departamento de Botânica, caique@power.ufscar.br
Leaf gas exchange characteristics were measured in twenty woody species of differing successional status ranging from pioneer species to non-pioneers (late successional species) in a Brazilian rain-reforestation ecosystem. Light saturated photosynthetic rate both calculated on either a leaf area (PNA) or a dry mass (PNM) basis, differed among species. PNA and PNM were highest in the pioneer species and lower in non-pioneer species. Variation among species was 3-fold (from 7 to 23 mmol m-2 s-1) for PNA, and 5-fold (from 50 to 275 mmol kg-2 s-1) for PNM. The highest PNA (23 mmol m-2 s-1) and PNM (275 mmol kg-2 s-1) values were recorded in the pioneer Croton urucurana, while the lowest PNA (7 mmol m-2 s-1) and PNM (50 mmol kg-2 s-1) values were recorded in the putative non-pioneer late successional specie Aspidosperma cylindrocarpon. C. urucurana also showed highest gs and E. Mass-based photosynthetic rate was highly correlated with SLM in both pioneer and non-pioneer species (r = -0.75 and -0.90, respectively). The highest values of instantaneous transpiratory efficiency (ITE) and intrinsic water use efficiency (iWUE) were also observed in the pioneer species when compared with the non-pioneer species. The results suggests that tropical pioneer species have greater ITE and iWUE than later successional species associated with their higher photosynthetic capacity. Multivariate principal components analysis (PCA) was useful to separate in a two-dimensional space the pioneer and non-pioneers species using gas exchange and SLM parameters. Supported by CNPq
Submitted by Carlos Alberto Martinez on 17-MAR-2004