DOI: 10.5061/dryad.2bvq83br2
title: Data from: Disentangling the factors that shape bromeliad and ant communities in the canopies of cocoa agroforestry and preserved Atlantic Forest

description: In tropical forest canopies, host tree characteristics shape epiphyte
 communities, and both host tree characteristics and epiphytes determine
 invertebrate communities, e.g., ants. Tree height is among the factors
 most often mentioned as a strong predictor for both bromeliad and ant
 communities. However, many factors interact dynamically in shaping the
 tree-bromeliad-ant association. Here, we investigated the effects of the
 host tree and canopy structural characteristics on both bromeliads and
 ants. We sampled bromeliads on 180 trees and ants in 360 bromeliads living
 on a subset of 60 of those trees in a continuum of native forest fragments
 and agroforestry systems in the Atlantic Forest, a Brazilian biodiversity
 hotspot. We found that the host trees’ crown area had a positive effect on
 the abundance of bromeliads. Also, the introduced tree species had higher
 abundance of bromeliads than native tree species. Moreover, we found that
 the ant species composition was different between native and introduced
 trees. In addition, we observed a positive effect of the size of
 bromeliads and tree crown height on ant species richness on both bromeliad
 and tree scales, but there was no effect of tree height. Taken together,
 our findings highlight the importance of trees with large crowns for the
 maintenance of bromeliads, which are also associated with richer ant
 communities in both Atlantic Forest and agroforestry systems. These
 results emphasize the importance of trees with larger crowns for
 biodiversity conservation in both native forest fragments and agroforestry
 systems.
description: <b>Study
 area</b> The study was carried out in a
 continuous patch of preserved fragment of Atlantic Forest and cacao
 agroforestry farm located in the micro-basin of the Una River in the Una
 municipality of the state of Bahia in northeastern Brazil (15° 17’ S, 39°
 07’ W). This region is part of the Central Atlantic Forest Corridor, one
 of the main areas of endemism of the Atlantic Forest (Myers et al., 2000).
 According to the Köppen classification (Alvares et al., 2013), the climate
 of the region is hot and humid (<i>Af</i>), with no defined
 dry season. The annual precipitation is greater than 1,300 mm and can
 reach 1,600 – 1,800 mm in rainy years (Mori 1989). The average annual
 temperature is 24.5 ºC, with warmer periods between October and April
 (maximum of 38 ºC), and periods with markedly lower temperatures between
 June and August (minimum of 7 ºC) (Mori 1989). The annual average relative
 humidity is 85%. The soil is typical Dystrophic Red-Yellow Latosol (Ker
 1994) and the dominant vegetation in the region is South Bahia
 Hygrophilous Forest (Gouvêa et al., 1976), or South Bahia Humid Forest,
 characterized by the presence of tall, broad-leaved evergreen trees with
 large numbers of lianas and epiphytes.
 <b>Sampling design</b> We sampled
 ants and bromeliads during the hottest and rainiest season of two
 consecutive years, from October 2013–April 2014 and from October
 2014–February 2015. Each of the three sampling points (Figure 1) contained
 a fragment of Atlantic Forest and an area of cacao agroforestry. Although
 the agroforestry system supported high biodiversity, this habitat differs
 greatly from the preserved Atlantic Forest. Agroforestry areas contained
 few native tree species, the trees are more isolated, and the understory
 is almost completely occupied by cocoa trees. However, cacao agroforestry
 system is a suitable habitat for many species of native fauna, which
 occupy these areas to feed and nest. In the preserved Atlantic Forest,
 only native tree species were found. Some native trees had been
 selectively logged in the past, but the fauna and flora are currently
 protected by strict conservation policy. We chose different species of
 host trees (phorophytes). In the fragments of Atlantic Forest, we
 considered native trees, while in the cacao agroforestry matrix (Johns
 1999), we included native trees as well as three introduced species:
 jackfruit (<i>Artocarpus heterophyllus</i>), erythrina
 (<i>Erythrina</i> spp.) and rubber tree (<i>Hevea
 brasiliensis</i>). We selected these introduced species because they
 are commonly used as shade trees in the mosaic of the cacao agroforestry
 landscape (Cassano et al., 2014). The fruits of jackfruit are widely used
 as food by the local population, as well as by native animal species such
 as the golden-headed lion tamarin, <i>Leontopithecus chrysomelas
 </i>Kuhl 1820, which forages and lives in these agroforests
 (Oliveira et al., 2011). Erythrina trees have been used as shade trees in
 cacao plantations since the 1960s based on the recommendation of the
 <i>Centro de Pesquisa da Lavoura Cacaueira</i> (CEPLAC), the
 Center for Research on Cacao Farming that guides the decisions of local
 farmers (Alvim 1966). Rubber tree was also introduced in the 1960s (Alvim
 & Nair 1986), and its use has now been strongly stimulated because
 the extraction of rubber in addition to coca increases the economic
 viability of farms through the diversification of crops.
 First, we selected 60 central point trees in the continuum of
 preserved fragment of Atlantic Forest and cacao agroforestry areas. These
 trees were the emergent ones whose tree-crowns were directly exposed to
 sunlight, with a minimum circumference at breast height (CBH) of 130 cm,
 i.e., about 41 cm of diameter at breast height (DBH). They are at a
 minimum of 50 m apart from the next central point tree and having at least
 six bromeliads in the crown of the tree. These central point trees
 consisted of 24 individuals of native species (12 on Atlantic Forest and
 12 on agroforestry system), and 36 individuals of the introduced
 species—12 erythrinas, 12 jackfruits and 12 rubber trees in the
 agroforestry system. We then selected two additional trees, close to the
 central point trees, that reached the canopy and had ≥130 cm of
 circumference at breast height (CBH), i.e., about 41 cm of diameter at
 breast height (DBH). This resulted in 60 central-point trees plus 120
 study trees, for a total of 180 trees. We identified all trees to the
 species (or morphospecies) level. <b>Sampling of
 bromeliads and ants</b> We counted and identified
 all bromeliads with a total length (from root to leaf end) greater than 10
 cm in each tree crown of the 180 selected trees. We conducted these counts
 from the ground, which although it can have some shortcomings
 (Flores-Palácios & García-Franco, 2001), is an efficient way to
 sample a large number of trees. Since we used the same ground-based
 approach across all samples, we were able to obtain sampling units that
 were comparable across all of our samples. We used the
 “<i>Encyclopaedia of Bromeliads</i>” (<i>version
 3.1</i>; Gouda et al., 2012) to identify all bromeliads to the
 species or morphospecies level whenever possible. Within the genera of
 bromeliads inventoried, some morphospecies were grouped into complexes
 because they could not be identified to the species level. Of the 180
 trees sampled, we excluded three tree individuals (1.7%) from the
 analyses: this consisted of one individual of <i>Spondias mombin
 </i>(Anacardiaceae), which was an exotic species not included among
 the list of three introduced species for sampling, and two rubber trees in
 which part of the sampled data was lost. Only the
 60-original central-point trees were used to study the ant fauna
 associated with bromeliads. We climbed each of these 60 central trees
 using an adaptation of the single rope climbing technique (Perry, 1978),
 in which one additional rope is added (double rope) in order to improve
 the climber’s movement within tree-crowns. We collected six bromeliads
 within a six-meter horizontal distance from the center of the tree crown,
 prioritizing those that were the largest and most accessible to the
 climber and as far from each other as possible, for a total of 360
 individual bromeliads. We used the “canopy hamper” method to collect the
 bromeliads and the associated ant fauna together with all of the
 associated organic matter and suspended soil (for details of this sampling
 technique, see: DaRocha et al., 2015a, Delabie et al., 2021). The ants
 associated with the suspended soil were extracted by direct collection
 using a Winkler trap while still in the field (Bestelmeyer et al., 2000).
 The collected ants were preserved in 92% alcohol in the field and then
 transported to the laboratory where they were mounted and when possible,
 identified to the species level using the entomological reference
 collection (CPDC) of the <i>Centro de Pesquisa do Cacau</i>
 CEPEC. <b>Vegetation
 variables</b> We measured tree- and
 canopy-related variables. Tree height of the 177 trees was estimated using
 a stick of known length by a single observer. In order to obtain the
 height of the tree crown, we first estimated the height of the first fork
 of the trees. Then, we obtained the height of the tree crown by
 subtracting the height of the first fork from the total height of each of
 the 177 trees. To obtain the area of the tree crown we measured the
 extension of tree crown from the ground, i.e., the projection of the tree
 crown on the ground. We quantified the percentage of canopy cover for each
 tree using hemispheric photography with a digital camera and an 8-15 mm
 180º <i>fisheye</i> lens (Rich 1990). Three hemispherical
 photographs were taken per tree, with the camera positioned at 1.8 m above
 the ground and 5 m away from the trunk of the tree, at 0 º, 120 º and 240
 º. The percentage canopy cover per tree was estimated from the photographs
 using the <i>RT4Bio </i>package (Reis-Jr et al., 2015) in the
 R environment (R Core Team 2017). To understand the
 relationship between bromeliad size and ant species richness, we
 determined the size of the bromeliads from which we sampled ants. The size
 (volume) of each of the 360 bromeliads collected were determined from the
 measurements in centimeters (cm) of the length of the innermost leaf of
 the rosette and the diameter of the rosette. We approximated the volume of
 the central part of the rosette to that of a cylinder
 (cm<sup>3</sup>), calculated as: <i>V</i> =
 <i>πr</i><sup>2</sup> * <i>h</i>,
 where: <i>r</i> is the rosette radius (cm) and
 <i>h</i> is the length of the most internal leaf (cm) (DaRocha
 et al., 2015a).