Determinants of Piper (Piperaceae) climber composition in a lowland tropical rainforest in New Guinea

Abstract

Climbing plants form a substantial component of tropical forest diversity. Climbers are a diverse group comprising various ecological strategies dependent on tree support and are affected by biotic and abiotic forest conditions. In a lowland primary tropical rainforest in Papua New Guinea, we studied the distribution of root climbers from genus Piper in relation to topography (slope, convexity, altitude) and properties of vegetation and of individual host trees (basal area of trees, and host tree size, abundance and species identity). In total, 1,058 Piper climber individuals belonging to 8 species occupied 13.7% of tree trunks with a diameter at breast height (DBH) > 1 cm. All Piper species generally avoided similar habitat conditions – higher altitude, steeper slopes, more closed canopy layer and bigger total basal area of host vegetation. The preferences of Piper climbers for some tree species are primarily determined by properties of host trees, mainly their DBH. Therefore, the probability of Piper presence on a tree increased with individual host tree DBH. Piper species were more frequently found on rare than common tree species. However, this relationship might be also explained by their affinity for higher tree DBH. Our findings point to non-random association between climbers and their host trees, in a complicated interplay with local environmental conditions. These interactions have very probably consequences for forest vegetation dynamics and maintenance of diversity.