Primary Succession along an Elevation Gradient 15 Years after the Eruption of Mount Pinatubo, Luzon, Philippines

Abstract

Abstract:We determined vegetation structure and environmental variables in the Pasig-Potrero and Sacobia River systems on the east flank of Mount Pinatubo, Luzon, Philippines, to define growth form and taxonomic groups that have influenced primary succession during the 15 yr since the eruption. We selected eight sites within an east-west range of 11.5 km, a north-south range of 7 km, and an elevation gradient of ca. 500 m. The 58 plant taxa we encountered among 63 sampled plots belonged to 21 families. Cover was dominated by Parasponia rugosa (tree) and Saccharum spontaneum (large grass). Cover of these two species was inversely related at the plot level. Exotic species represented nearly 60% of this flora but only 32% of the vegetation cover. Family richness was high for Asteraceae, Fabaceae, and Poaceae. Elevation, distance to the caldera, and distance to human settlement exhibited the most control over the vegetation. The influence of elevation on cover, species composition, and structure differed in these adjacent canyons. Plot species richness, cover, and diversity indices were greatest at the highest elevation of the Pasig-Potrero River. On a small scale, current dominant species may control progression of species assemblages as mediated by geophysical, chemical, facilitative, and competitive changes. Our findings indicate that ongoing anthropogenic disturbances and the prevalence of exotic species may prevent the vegetation from returning to its preeruption state. The invasive Pennisetum setaceum and Chromolaena odorata were widespread in this landscape, and their negative influence on vegetation recovery is probable. Ours is the first detailed survey of vegetation on newly created volcanic surfaces in the region and provides a baseline for understanding the landscape-level processes determining continuing succession.

Factors Determining Forest Diversity and Biomass on a Tropical Volcano, Mt. Rinjani, Lombok, Indonesia

“…The environments immediately resulting from volcanic eruptions are not suitable for most life forms [35], but over time, as a soil develops, detritivore and scavenger based communities are replaced by early successional communities dominated by pioneer plants and associated fauna, and thereafter community recovery proceeds more rapidly [31], [36], [37]. However, to date most of the studies on volcanoes have dealt with the recolonisation and successional processes following eruption [31], [38], [39]. Tropical volcanoes comprise an important ecosystem, particularly in SE Asia, that differs in important ways from non-volcanic mountain ecosystems in the tropics.…”

Recovering plant biodiversity

“…1 This pattern was likely a result of greater population density of native animal dispersers that vector the Musa seeds into the canyons four large grasses allow this functional group to maintain integrity of ecosystem services in diverse habitats. Conversely, ecosystem services provided by a species that lacks redundancies may be at greater risk during continued disturbances.…”

“…1 For example, species that belong to functional groups with redundancies may provide ecosystem services that are duplicated by the other taxa in the functional group. The four large grasses in Mount Pinatubo provide a pertinent example.…”

“…Therefore, we recently published an exhaustive list of vascular plants that have assembled on two disturbed riparian drainages on the eastern flanks of Mount Pinatubo. 1 As the first paper of its kind on Mount Pinabuto, the results may aid in understanding tropical vegetation recovery following destruction or damage by other disturbances such as agriculture, landslides and forestry. 2 Here I explore issues and observations that resulted from the field work and data analysis, focusing on potential drivers of floristic diversity and distribution.…”

Invasions of Plant Communities – More of the Same, Something Very Different, or Both?

“…Mt. Pinatubo, in the Philippines (not listed), the other great 20th century volcanic eruption (Gran and Montgomery, 2005) has been studied sparingly (Marler and del Moral, 2010) due to its isolation and political unrest. Only stable floodplains have developed greatly and the vegetation there is strongly influenced by agricultural species.…”