Vegetation Analysis of the Pasonanca Natural Park, Zamboanga City, Philippines

This study was a vegetation analysis of the Pasonanca Natural Park. The lack of recent biological studies focusing on the flora of the park has left many of its species, including their status unknown. Some of the species are of global conservation importance. The sampling sites covered Canucutan, Muruk 3 and Baluno. Three stations were established at intervals of 300 m each in Canucutan and Muruk 3 and 4 stations in Baluno. Five nested quadrats, each measuring 100 m 2 with subplots measuring 5m x 5m and 1m x 1m were plotted at intervals of 10 m in each station. There were 283 individuals belonging to 45 species, 27 genera and 25 families. The taxonomic composition was mainly angiosperms and Pteridophytes comprising 37 (82.22%) and 8 (17.78%) respectively. There were 30 species with known geographic range; and of these, 60% were endemic or native, 33.33% were cosmopolitan and 6.67% were exotic. Data on species composition, distribution, importance values, and diversity indices show that species diversity is high in all 3 sites. Species evenness though was fairly high in Canucutan compared to Muruk 3 and Baluno based on Simpson’s measure of evenness. Conversely, all 3 sites have comparatively high species evenness based on Shannon-Wiener’s measure of evenness. There were few species under the threatened category (either vulnerable or critically endangered). Several species though were either not threatened (33%) or not evaluated (27%). The ecologically important species belong to families Araceae, Arecaceae, Euphorbiaceae, Maranthaceae and Athyriaceae. Keywords : Vegetation analysis, species diversity, species evenness, Natural Park