Biodiversity in tropical plantations is influenced by surrounding native vegetation but not yield: A case study with dung beetles in Amazonia

Emma J. Sayer,Jos Barlow,Wallace Beiroz,Julio Louzada,Cézar Borges,Eleanor M. Slade

doi:10.1016/j.foreco.2019.04.036

Abstract

Human-modified forests, including plantations and managed forest, will be a major component of tropical landscapes in the near future. To conserve biodiversity across modified tropical landscapes we must first understand what influences diversity in planted areas. We studied dung beetle communities in Eucalyptus plantations to assess the influence of local (canopy openness and soil texture) and landscape factors (surrounding native forest cover) on taxonomic and functional diversity, and to determine whether biodiversity in plantations is affected by timber production. Dung beetle community composition in Eucalyptus plantations was largely explained by the surrounding native forest cover, as Simpson’s diversity and functional diversity (Rao’s quadratic entropy) increased with the extent of native forest in buffer areas. However, the abundance of dung beetle species associated with native forest was not explained by any of the explanatory variables. The coarse sand content of the soil explained much of the functional similarity between plantations and native forests, as well as variation in dung beetle community structure. The total abundance of dung beetles in plantations increased with coarse sand content, whereas body mass declined, and dung beetle abundance and functional originality decreased with canopy openness. Timber production intensity did not explain the variation in any of the measured diversity parameters. If enhancing biodiversity in plantations is a management goal, then these results highlight the importance of restoring or retaining native forest areas in modified landscapes. They also suggest that integrated management could improve biodiversity in Eucalyptus plantations without reducing timber production.

Highlights

Planted forests are rapidly expanding at a rate of around 5 million ha-1 yr-1, with much of that increase occurring in tropical landscapes as a result of the growing global demand for timber, cellulose and oils (FAO 2010, Vijay et al 2016)
We evaluated the extent of native forest cover around each plantation as a key landscape condition, as dung beetle communities in modified habitats may depend on native forest as a source of species (Gray et al 2016)
We evaluated how local forest structure, landscape context and timber production influence the taxonomic and functional diversity of dung beetles in Eucalyptus plantations

Summary

Introduction

Planted forests are rapidly expanding at a rate of around 5 million ha-1 yr-1, with much of that increase occurring in tropical landscapes as a result of the growing global demand for timber, cellulose and oils (FAO 2010, Vijay et al 2016). A growing number of studies have shown how some taxa can persist in tropical crops that emulate structural aspects of native forests and landscapes, including cocoa agroforestry (Schroth and Harvey 2007, Cassano et al 2012), oil palm (Koh and Wilcove 2008, Gray et al 2014, Dislich et al 2016), coffee plantations (Tadesse et al 2014), and timber monocultures including Eucalyptus (Bremer and Farley 2010). Native species from forest remnants can improve ecosystem functioning within modified areas (Blitzer et al 2012), ecosystem processes can change as a result of the distinct functional structure of the biological community in the modified habitats (Hobbs et al.2009, Tavares et al 2019)

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Conclusion