Wood specific gravity of trees in Amazonian white-water forests in relation to flooding

Abstract

Wood specific gravity (SG) was analysed from wood cores of 180 individuals belonging to 58 common upper canopy tree species of late successional white water (várzea) forests in the Mamirauá Sustainable Development Reserve, Central Amazon Basin. We tested for a SG gradient of trees along the flood gradient. Mean SG in the low várzea was 0.62 g cm-3, in the high várzea 0.57 g cm-3. SG tended to increase with height and duration of flooding. In the two species that occurred in both forest types (Hevea spruceana, Tabebuia barbata) SG was significantly lower in the high várzea trees. Therefore, height and duration of flooding seem to be important factors influencing growth and wood properties in várzea trees. In addition, SG variation depended on the core section and to a lesser extent on tree diameter and height. Compared to trees in Amazonian upland ecosystems, SG of the várzea trees was lower than SG in Central and Eastern Amazonian terra firme, but was within the same range reported for Western Amazonian terra firme.