A comparison of five indirect methods for characterizing the light environment in a tropical forest

Abstract : We compared five methods for measuring light availability in the tropical forest understorey: the LAI-2000 PCA, an empirical LAI-metre, a densiometre, photosensitive diazo paper metres, and hemispherical photographs. Measurements were made along three 250 m transects and adjacent to 95 seedlings on four logged or virgin plots of a French Guianese forest. Correlation analysis showed that more mobile and less expensive methods, such as the LAI metre and diazo paper metres, can provide similar information to more cumbersome or expensive equipment such as the LAI-2000 metre or hemispherical photographs. All instruments except the densiometre detected differences among seedlings from different post-logging microsites. Few significant correlations were found between light measures and the number of trees or their basal area within 10 m, which may reflect an increase in the density of smaller stems and lianas during post-logging succession.