DOI: 10.5061/dryad.zcrjdfnf2
title: Removing understory vegetation in oil palm agroforestry reduces ground-foraging ant abundance but not species richness

description: Ants are known to provide valuable ecosystem services in agricultural
 landscapes, including oil palm plantations. Their communities are less
 diverse and more uneven in oil palm compared with forest, and this may
 increase their vulnerability to disturbance. This study quantifies ant
 communities in oil palm agroforestry and experimentally tests their
 robustness to a common-practice high-disturbance management intervention:
 removing understory vegetation. Fieldwork was based at the Biodiversity
 and Ecosystem Function in Tropical Agriculture (BEFTA) Understory
 Vegetation Project in Sumatra, Indonesia, where three treatments varying
 in their degree of understory vegetation management were established in
 2014: (1) widespread herbicide was applied removing all understory
 vegetation (Reduced); (2) herbicide was applied to the harvesting paths
 and circles, and other vegetation was allowed to grow (Normal – control);
 (3) no herbicide was applied (Enhanced). We measured ground-foraging ant
 communities before and after the treatments were implemented, using
 pitfall traps over 324 trap-nights (a trap-night is one trap set for one
 night). We investigated how ant abundance, species richness, species
 evenness, beta diversity, and community composition differed between the
 treatments. We found 3507 ants across 68 species or morphospecies. Seven
 of these were highly abundant and accounted for 78% of individuals.
 Post-treatment ant abundance was lower in the reduced treatment (mean per
 plot: 84) than in the normal (159) and enhanced (131) treatments, which
 did not differ from each other. Species richness, species evenness, beta
 diversity and community composition were not affected by the vegetation
 treatments. We recommend that oil palm growers maintain understory
 vegetation in oil palm plantations to support ground-foraging ants. Though
 not tested here, this may also improve ant-mediated ecosystem services,
 such as pest control, seed dispersal, nutrient redistribution, and the
 maintenance of soil health. This study demonstrates that enhancing habitat
 complexity through management practices can support biodiversity in
 monocrop landscapes.
description: Fieldwork was based in oil palm plantations at the Biodiversity
 and Ecosystem Function in Tropical Agriculture (BEFTA) Understory
 Vegetation Project in Sumatra, Indonesia, where three treatments varying
 in their degree of understory vegetation management were established in
 February 2014: 
 <strong>Reduced complexity (Reduced)</strong>:
 Mature first-generation plantation with all understory vegetation removed
 by spraying herbicide. <strong>Normal
 complexity</strong> <strong>(Normal)</strong>: Mature
 first-generation plantation with understory vegetation removed from the
 harvesting paths and harvesting circle (a ~1.5m radius area around the
 base of each palm) using herbicide, and large woody vegetation removed
 manually. Other vegetation was allowed to grow. This is standard industry
 practice in these estates. <strong>Enhanced
 complexity (Enhanced)</strong>: Mature first-generation plantation
 with the same understory management as the normal complexity, except
 harvesting paths and circles were cleared by strimming rather than
 herbicide. We measured ground-foraging ant
 communities before (March-April 2013) and after (September 2014) the
 treatments were implemented. We set three pitfall traps in each plot.
 Traps were 50 m apart, arranged in an equilateral triangle that was
 centred in each plot. Each trap was active for three days. This amounted
 to 108 traps over 324 trap-nights. Traps consisted of circular 20 cm
 diameter funnels, leading to a pot of 75% alcohol. Worker ants were
 identified to genus using keys, and to morphospecies or species where
 possible.
description: There are one dataset which shows the abundance of each ant
 morphospecies and their genus. One species (MS.5 Pheidole in dataset or
 Pheidole sp.1 in manuscript) may be a multispecies complex, as workers
 varied in size and colouration; there were no clear divisions along which
 to assign different species, so all individuals in this group were
 combined into a single morphospecies.