UCB Moorea Class: Biology and Geomorphology of Tropical Islands

Wood-decaying macrofungi are an important component of forest ecosystems because they are the major decomposers of dead woody debris and are crucial for nutrient cycling. This is especially true in the tropics where biomass is high. However, most studies to date have focused on temperate forests in the northern hemisphere. Little is known about wood-inhabiting fungi in French Polynesia. In fact, no identification materials exist. The following study seeks to fill this gap in knowledge. First, a general survey was done of the wood-fungi occurring in the mountains of Moorea. Next, in a pilot study, all Hibiscus tiliaceus dead wood (>1cm) was measured and surveyed for fungi using 10, 25-meter line transects. The aim of this phase was to determine if wood with fungi has different characteristics than wood without. Fungi were found on 61% of wood surveyed, but larger logs, and wood of intermediate decay were more likely to have at least one species. An additional 20 transects focused only on wood with fungi. A total of 114 species were found on 644 pieces of Hibiscus tiliaceus wood. However, 36.8% species were found only once and most wood had only 1 or 2 species. There were a few very abundant species, and the others were rare. When common species were examined individually, it was evident that many had preferences for certain wood sizes and decomposition. Species richness was found to positively correlate with average diameter, and wood of intermediate decay was also found to have greater species richness. In general, the results of this study were found to support much of the research conducted in temperate forests. Although the details differ, the underlying trends of diversity and succession are surprisingly similar.