Diversity Patterns of Tropical Epigeal Beetle Assemblages Associated with Monoculture and Polyculture Plantations with Big-Leaf Mahogany.

Abstract

Although commercial forest plantations have experienced a major growth in the tropics over the past decades, little attention has been paid to their role in the conservation of epigeal arthropod communities. We studied diversity patterns of the epigeal beetle community in monoculture and polyculture forest plantations with big-leaf mahogany (Swietenia macrophylla). Likewise, we explored the existence of indicator species of each plantation type. Our findings highlight that each plantation type promotes multiple impacts on diversity patterns. We found that monocultures positively influenced overall beetle species richness and ecological diversity. When broken down by guild, both predator and decomposer species richness were similar between monoculture and polyculture, whereas for beetle diversity we found contrasting responses by guild: decomposer diversity was greater in monoculture whereas predator diversity was higher in polyculture. In addition, species composition differed between monoculture and polyculture, except for the predator guild. Species turnover was the main component explaining beta diversity patterns at all levels, indicating that each plantation type promotes biologically distinct epigeal assemblages. Few superabundant heliophile species dominated the beetle community structure; moreover, monocultures had a composition skewed towards heliophile species whereas polyculture favored umbrophile species. These patterns could be attributed to differences in habitat complexity between plot types, namely differences in tree cover. Additionally, indicator species only were identified in polycultures, reflecting their higher spatial complexity. Monoculture and polyculture plantations with big-leaf mahogany are complementary agroecosystems for preserving diverse epigeal beetle communities and should be considered valuable tools for conservation purposes in the tropics.