Relative effects of edaphic conditions and climate on palm communities in the Central Andes

Abstract

Palms (family Arecaceae) are conspicuous and structural elements in forests ecosystems of tropical regions and mountain forests in South America. Additionally, many species of palms are culturally and economically important to human populations. Because of their ecological and ethnobotanical significance, understanding the drivers of palm distribution and diversity is critical. However, most past research has focused in tropical lowland palm communities, while our understanding of montane tropical palm ecology and biogeography is comparatively lacking. We investigate the environmental factors that influence patterns of richness, composition, and abundance of palms in the Central Andes. In particular, we are interested in the relative effects that soil edaphic conditions and climate have on palm community structure. For these analyses, we used a network of 88 forest plots distributed along a broad elevational gradient (1,000 - 3,200 meters), which are part of the Madidi Project in north-western Bolivia. We carried out palm community-level analysis, as well as species-specific analyses for each of the 16 most common species. We found that soils and climate contribute differentially to shaping Andean palm diversity and distributions. We found that soils explain more variation in species composition (14.4%) than climate (3.45%), but that climate explains more variation in species richness (13%) than soils (6.1%). Moreover, species-specific analyses reveal that there is great variation in how different common species respond to their abiotic environment. Our results contribute to understanding the drivers of biodiversity for a highly important group of plants in one of the most important hotspots for biodiversity.