Tropical Plant Research

Sutomo*, Richard J. Hobbs and Viki A. Cramer

Abstract:
Patterns of plant community structure and composition during secondary succession following volcanic-fire induced disturbance of nuées ardentes was examined in Mount Merapi National Park, Indonesia. Five sites with different age (time since fire) and one undisturbed site were sampled. Species richness, diversity, turnover and importance value index (IVI) were calculated. Sixty one species belonging to 29 families were recorded in the study sites. The highest number of species belonged to the Poaceae (10), followed by Fabaceae (9) and then Asteraceae (6). The number of species present varied as time progressed with a rising trend of species richness and diversity over time and significant differences in species richness and diversity among sites (ANOVA, p = 0.05). Species turnover was highest between the 2006 and 1998 sites, and then between the 1997 and 1994 sites. Species turnover between the 1998-1997 sites was similar to the turnover between the 1994 site and the reference site. In terms of vertical structure, four strata were identified in the fire sites whereas in the reference site, all five stratums (A, B, C, D, and E) were present. In terms of quantitative structure based on IVI, each site had different dominating species for tree, groundcover and seedling layers. Non metric multidimensional scaling (NMDS) ordination of plots and analysis of similarity (ANOSIM) test results showed that there were significant differences in species composition between sites (Global R_ANOSIM = 0.93, P < 0.001). In the Mount Merapi succession, the changes in abundance of some invasive species such as I. cylindrica, Brachiaria spp., and Eupatorium spp. are important to note. These invasive species have different timing in entering the system, but Imperata cylindrica was noted almost constantly in every stage of succession except in the undisturbed site.