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

Abstract

Tropical volcanoes are an important but understudied ecosystem, and the relationships between plant species diversity and compositional change and elevation may differ from mountains created by uplift, because of their younger and more homogeneous soils. We sampled vegetation over an altitudinal gradient on Mt. Rinjani, Lombok, Indonesia. We modeled alpha- (plot) and beta- (among plot) diversity (Fisher's alpha), compositional change, and biomass against elevation and selected covariates. We also examined community phylogenetic structure across the elevational gradient. We recorded 902 trees and shrubs among 92 species, and 67 species of ground-cover plants. For understorey, subcanopy and canopy plants, an increase in elevation was associated with a decline in alpha-diversity, whereas data for ground-cover plants suggested a hump-shaped pattern. Elevation was consistently the most important factor in determining alpha-diversity for all components. The alpha-diversity of ground-cover vegetation was also negatively correlated with leaf area index, which suggests low light conditions in the understorey may limit diversity at lower elevations. Beta-diversity increased with elevation for ground-cover plants and declined at higher elevations for other components of the vegetation. However, statistical power was low and we could not resolve the relative importance to beta-diversity of different factors. Multivariate GLMs of variation in community composition among plots explained 67.05%, 27.63%, 18.24%, and 19.80% of the variation (deviance) for ground-cover, understorey, subcanopy and canopy plants, respectively, and demonstrated that elevation was a consistently important factor in determining community composition. Above-ground biomass showed no significant pattern with elevation and was also not significantly associated with alpha-diversity. At lower elevations communities had a random phylogenetic structure, but from 1600 m communities were phylogenetically clustered. This suggests a greater role of environmental filtering at higher elevations, and thus provides a possible explanation for the observed decline in diversity with elevation.

Phylogenetic diversity in the Western Ghats biodiversity hotspot reflects environmental filtering and past niche diversification of trees

“…Temperature stress at high altitudes could result in phylogenetic clustering, as reported for other taxa like birds, bees, butterflies, microbes (Qian et al, 2014 and references therein), and plants (e.g., Dossa et al, 2013). However, we found deep phylogenetic overdispersion in higher elevation forests.…”

New insights on above ground biomass and forest attributes in tropical montane forests

“…Compared with TMF outside Africa, our AGB estimates (which range from 117 to 612 Mg ha -1 , mean of all plots studied 276 Mg ha -1 ) seem high, particularly in Mt Nyiro. For example, AGB ranged between and 200 Mg ha -1 (1500-2500m) in Andean TMF (Girardin et al, 2014), between 100 and Mg ha -1 (1000 and 2200m) at Mt Rinjani in Indonesia (Dossa et al, 2013), while it was estimated at Mg ha -1 and 271 Mg ha -1 for submontane and montane Atlantic forest in Brazil (Alves et al, 2010). Interestingly, it has been reported that Asian and Neotropical TMFs have similar mean AGB (257 and 247 Mg ha −1 , n = 31 and 56, respectively) while that of African TMF is higher (527 Mg ha −1 n = 7) (Spracklen and Righelato, 2014).…”

“…Generally, there is a decline in tree species richness with increasing altitude (e.g. Dossa et al, 2013;Sassen and Sheil, 2013;Girardin et al, 2014), because of a greater role of environmental filtering at higher elevations (e.g. cooler temperatures, fog, reduced light incidence and higher relative humidity).…”

Retrieval of Tropical Peatland Forest Biomass From Polarimetric Features in Central Kalimantan, Indonesia

“…Recently, many researchers have found that forest diversity is positively linked with aboveground biomass [45][46][47][48][49]. However, the quantitative relationship between AGB and structure -species diversity is poorly understood.…”