Wood-nesting ants and their parasites in forests and coffee agroecosystems

Agricultural intensification is linked to reduced species richness and may limit the effectiveness of predators in agricultural systems. We studied the abundance, diversity, and species composition of wood-nesting ants and frequency of parasitism of poneromorph ants in coffee agroeco systems and a forest fragment in Chiapas, Mexico. In three farms differing in shade management and in a nearby forest fragment, we surveyed ants nesting in rotten wood. We collected pupae of all poneromorph ants encountered, and incubated pupae for 15 d to recover emerging ant parasites. If no parasites emerged, we dissected pupae to examine for parasitism. Overall, we found 63 ant morphospecies, 29 genera, and 7 subfamilies from 520 colonies. There were no significant differences in ant richness or abundance between the different sites. However, there were significant differences in the species composition of ants sampled in the four different sites. The parasitism rates of ants differed according to site; in the forest 77.7% of species were parasitized, and this number declined with increasing intensification in traditional polyculture (40%),commercial polyculture (25%), and shade monoculture (16.6%). For three of four poneromorph species found in >1 habitat, parasitism rates were higher in the more vegetatively complex sites. The result that both ant species composition and ant parasitism differed among by site indicates that coffee management intensification affects wood-nesting ant communities. Further, coffee intensification may significantly alter interactions between ants and their parasites, with possible implications for biological control in coffee agroecosystems.     

Limitation of nesting resources for ants in Colombian forests and coffee plantations

Abstract.  1. This study examines limitation of nesting resources for leaf-litter and twig-nesting ants as a mechanism of diversity loss across an intensification gradient of coffee production in Colombia. Twelve farms were selected and classified into four management types: forest, polygeneric shade coffee, monogeneric shade coffee, and sun coffee (unshaded coffee monocultures).
2. At each of the farms, four treatment subplots were established at the corners of each of 10 25 m² plots: (i) twig augmentation (adding 10 empty bamboo twigs); (ii) litter augmentation (tripling existing litter profile); (iii) twig and litter augmentation; and (iv) no manipulation control, for a total of 480 subplots. A twig addition experiment was also performed on coffee bushes.
3. The results showed significantly more ant colonies in the forest and monogeneric shade coffee litter augmentation plots after 4 months. Litter-nesting ant species richness was higher in all three shade systems than in the sun coffee. The identities of ants nesting on coffee bushes were different from those in the soil level litter. Fewer species nested in bamboo twigs placed in litter in the most intensive systems.
4. More ants nested in the resource addition treatments, and more ant species were found in forested habitats; however, a single mechanism cannot explain the observed patterns. It was concluded that a combination of bottom-up and top-down effects might lead to the loss of associated fauna with the intensification of these agroecosystems.     

Conservation Value of Cacao Agroforestry Systems for Terrestrial Herbaceous Species in Central Sulawesi,Indonesia

Tropical secondary forest and agroforestry systems have been identified as important refuges for the local species diversity of birds and other animal groups, but little is known about the importance of these systems for terrestrial herbs. In particular, few studies report how the conversion from tropical forest to technified cacao plantation affects the species richness and the community structure of herbs. We conducted surveys in 43 cacao plantations along the border of the Lore Lindu National Park in Central Sulawesi, ranging from agroforests to technified cacao, categorizing the plantations as rustic cacao, planted shade cacao, and technified cacao. We recorded 91 herb species. Of the 74 species determined to species level, 21 were also found in natural forests, while 53 were recorded only in agricultural habitats. Araceae was the most forest‐dependent plant family while Asteraceae included the highest number of nonforest species. Overall, the presence of forest species was confined to moderately intensively managed rustic and planted shaded plantations. Distance from the forest, which has been identified as a crucial parameter for the diversity and composition of other taxa in cacao agroforests, only played a minimal role for herbs. Our study suggests that native forest herbs maybe more vulnerable to forest conversion than animal groups. The intensification of cacao plantation management increases the presence of weedy species to the detriment of native forest species.     

Spillover of Insects from Rain Forest into Adjacent Oil Palm Plantations

Conversion of natural forest to oil palm plantations is a major threat to biodiversity in Southeast Asia. The retention of natural forest habitats within plantations has been proposed as a method to reduce biodiversity losses in agricultural areas, and we examined whether forest areas resulted in spillover of species into adjacent oil palm plantations. We sampled ants and butterflies along two 2‐km transects across an ecotone from plantation into adjacent forest in Sabah, Malaysian Borneo. Species richness of both taxa was reduced in plantations, but to a greater extent in butterflies (54% reduction) than in ants (25% reduction). Butterfly diversity increased in plantations with increasing proximity to forest primarily due to spillover of ‘vagrant’ forest species (whose larval host plants do not occur in plantations), although richness of species that could potentially breed in plantations also increased near to forest. By contrast, ants showed no spillover effects and were less sensitive to land‐use changes, with much higher levels of similarity in species assemblages across habitats than for butterflies. Our results for butterflies suggest that despite the negative impacts of plantations on diversity, proximity to forest could improve diversity in adjacent plantations for some taxa. Spillover of forest species implies that retaining forest areas within plantations may be important for facilitating dispersal of some species through the landscape.     

Ensemble composition and activity levels of insectivorous bats in response to management intensification in coffee agroforestry systems

Shade coffee plantations have received attention for their role in biodiversity conservation. Bats are among the most diverse mammalian taxa in these systems; however, previous studies of bats in coffee plantations have focused on the largely herbivorous leaf-nosed bats (Phyllostomidae). In contrast, we have virtually no information on how ensembles of aerial insectivorous bats--nearly half the Neotropical bat species--change in response to habitat modification. To evaluate the effects of agroecosystem management on insectivorous bats, we studied their diversity and activity in southern Chiapas, Mexico, a landscape dominated by coffee agroforestry. We used acoustic monitoring and live captures to characterize the insectivorous bat ensemble in forest fragments and coffee plantations differing in the structural and taxonomic complexity of shade trees. We captured bats of 12 non-phyllostomid species; acoustic monitoring revealed the presence of at least 12 more species of aerial insectivores. Richness of forest bats was the same across all land-use types; in contrast, species richness of open-space bats increased in low shade, intensively managed coffee plantations. Conversely, only forest bats demonstrated significant differences in ensemble structure (as measured by similarity indices) across land-use types. Both overall activity and feeding activity of forest bats declined significantly with increasing management intensity, while the overall activity, but not feeding activity, of open-space bats increased. We conclude that diverse shade coffee plantations in our study area serve as valuable foraging and commuting habitat for aerial insectivorous bats, and several species also commute through or forage in low shade coffee monocultures.     

Bats are Not Birds – Different Responses to Human Land‐use on a Tropical Mountain

Land‐use intensification has consequences for biodiversity and ecosystem functioning, with various taxonomic groups differing widely in their sensitivity. As land‐use intensification alters habitat structure and resource availability, both factors may contribute to explaining differences in animal species diversity. Within the local animal assemblages the flying vertebrates, bats and birds, provide important and partly complementary ecosystem functions. We tested how bats and birds respond to land‐use intensification and compared abundance, species richness, and community composition across a land‐use gradient including forest, traditional agroforests (home garden), coffee plantations and grasslands on Mount Kilimanjaro, Tanzania. Furthermore, we asked how sensitive different habitat and feeding guilds of bats and birds react to land‐use intensification and the associated alterations in vegetation structure and food resource availability. In contrast to our expectations, land‐use intensification had no negative effect on species richness and abundance of all birds and bats. However, some habitat and feeding guilds, in particular forest specialist and frugivorous birds, were highly sensitive to land‐use intensification. Although the habitat guilds of both, birds and bats, depended on a certain degree of vegetation structure, total bat and bird abundance was mediated primarily by the availability of the respective food resources. Even though the highly structured southern slopes of Mount Kilimanjaro are able to maintain diverse bat and bird assemblages, the sensitivity of avian forest specialists against land‐use intensification and the dependence of the bat and bird habitat guilds on a certain vegetation structure demonstrate that conservation plans should place special emphasis on these guilds.     

Effects of Habitat Structure and Adjacent Habitats on Birds in Tropical Rainforest Fragments and Shaded Plantations in the Western Ghats, India

As large nature reserves occupy only a fraction of the earth’s land surface, conservation biologists are critically examining the role of private lands, habitat fragments, and plantations for conservation. This study in a biodiversity hotspot and endemic bird area, the Western Ghats mountains of India, examined the effects of habitat structure, floristics, and adjacent habitats on bird communities in shade-coffee and cardamom plantations and tropical rainforest fragments. Habitat and birds were sampled in 13 sites: six fragments (three relatively isolated and three with canopy connectivity with adjoining shade-coffee plantations and forests), six plantations differing in canopy tree species composition (five coffee and one cardamom), and one undisturbed primary rainforest control site in the Anamalai hills. Around 3300 detections of 6000 individual birds belonging to 106 species were obtained. The coffee plantations were poorer than rainforest in rainforest bird species, particularly endemic species, but the rustic cardamom plantation with diverse, native rainforest shade trees, had bird species richness and abundance comparable to primary rainforest. Plantations and fragments that adjoined habitats providing greater tree canopy connectivity supported more rainforest and fewer open-forest bird species and individuals than sites that lacked such connectivity. These effects were mediated by strong positive effects of vegetation structure, particularly woody plant variables, cane, and bamboo, on bird community structure. Bird community composition was however positively correlated only to floristic (tree species) composition of sites. The maintenance or restoration of habitat structure and (shade) tree species composition in shade-coffee and cardamom plantations and rainforest fragments can aid in rainforest bird conservation in the regional landscape.     

Local and landscape drivers of biodiversity of four groups of ants in coffee landscapes

Agriculture of varying management intensity dominates fragmented tropical areas and differentially impacts organisms across and within taxa. We examined impacts of local and landscape characteristics on four groups of ants in an agricultural landscape in Chiapas, Mexico comprised of forest fragments and coffee agroecosystems varying in habitat quality. We sampled ground ants found in leaf litter and rotten logs and arboreal ants found in hollow coffee twigs and on tree trunks. Then using vegetation and agrochemical indices and conditional inference trees, we examined the relative importance of local (e.g. vegetation, elevation, agrochemical) and landscape variables (e.g. distance to and amount of nearby forest and rustic coffee) for predicting richness and abundance of ants. Leaf litter ant abundance increased with vegetation complexity; richness and abundance of ants from rotten logs, twig-nests, and tree trunks were not affected by vegetation complexity. Agrochemical use did not affect species richness or abundance of any ant group. Several local factors (including humus mass, degree of decay of logs, number of hollow twigs, tree circumference, and absence of fertilizers) were significant positive predictors of abundance and richness of some ant groups. Two landscape factors (forest within 200 m, and distance from forest) predicted richness and abundance of twig-nesting and leaf litter ants. Thus, different ant groups were influenced by different characteristics of agricultural landscapes, but all responded primarily to local characteristics. Given that ants provide ecosystem services (e.g. pest control) in coffee farms, understanding ant responses to local and landscape characteristics will likely inform farm management decisions.     

Heard but not seen: Comparing bat assemblages and study methods in a mosaic landscape in the Western Ghats of India

We used capture (mist‐netting) and acoustic methods to compare the species richness, abundance, and composition of a bat assemblage in different habitats in the Western Ghats of India. In the tropics, catching bats has been more commonly used as a survey method than acoustic recordings. In our study, acoustic methods based on recording echolocation calls detected greater bat activity and more species than mist‐netting. However, some species were detected more frequently or exclusively by capture. Ideally, the two methods should be used together to compensate for the biases in each. Using combined capture and acoustic data, we found that protected forests, forest fragments, and shade coffee plantations hosted similar and diverse species assemblages, although some species were recorded more frequently in protected forests. Tea plantations contained very few species from the overall bat assemblage. In riparian habitats, a strip of forested habitat on the river bank improved the habitat for bats compared to rivers with tea planted up to each bank. Our results show that shade coffee plantations are better bat habitat than tea plantations in biodiversity hotspots. However, if tea is to be the dominant land use, forest fragments and riparian corridors can improve the landscape considerably for bats. We encourage coffee growers to retain traditional plantations with mature native trees, rather than reverting to sun grown coffee or coffee shaded by a few species of timber trees.     

Bird communities of natural and modified habitats in Panama

Only a small proportion of land can realistically be protected as nature reserves and thus conservation efforts also must focus on the ecological value of agroecosystems and developed areas surrounding nature reserves. In this study, avian communities were surveyed in 11 habitat types in central Panama, across a gradient from extensive forest to intensive agricultural land uses, to examine patterns of species richness and abundance and community composition. Wooded habitats, including extensive and fragmented forests, shade coffee plantations, and residential areas supported the most species and individuals. Nearctic-Neotropical migratory species were most numerous in lowland forest fragments, shade coffee, and residential areas. Introduced Pinus caribbea and sugar cane plantations supported the fewest species compared to all other habitats. Cattle pastures left fallow for less than two years supported more than twice as many total species as actively grazed pastures, such that species richness in fallow pastures was similar to that found in wooded habitats. Community similarities were relatively low among all habitat types (none exceeding the observed 65% similarity between extensive and fragmented lowland forests), but communities in shade coffee and residential areas were 43% and 54′% similar to lowland forest fragments, respectively. Fallow pastures and residential areas shared 60% of their species. Bird communities in shade coffee and residential areas were characterized by higher proportions of frugivorous and nectarivorous species than in native forests. These same guilds also were better represented in fallow than in grazed pastures. Raptors and piscivorous species were most prevalent in cattle pastures and rice fields. These results, though based upon only species richness and abundance, demonstrate that many human-altered habitats have potential ecological value for birds, and conservation efforts in tropical areas should focus greater attention on enhancement of agricultural and developed lands as wildlife habitat. To understand the true conservation value of these modified lands will require examination not only of numbers but also of the types of species supported by these habitats, their reproductive output and survival rates.     

The role of rustic coffee plantations in the conservation of wild tree diversity in the Chinantec region of Mexico

Rustic coffee plantations are characterised by the use of numerous wild and cultivated tree species for providing shade to the coffee shrubs. This paper analyses the role of these plantations in wild tree conservation through the examination of their patterns of floristic variation in southern Mexico. The studied plantations included a total of 45 plant species, most of which were wild tree species, including both mature forest and pioneer taxa. An extrapolation of the species accumulation curve among stands indicated that the whole system, composed of more than 100 coffee plantations, may harbour as many as 34 species of wild trees. The floristic structure of rustic coffee plantations was highly variable. This variation is a result of a combination of factors such as human management, original stand cover and the asynchrony in development stage of different plantations. This promotes a large -diversity in the system. Thus, although a single plantation may have a limited potential to preserve wild tree species, it is the whole ensemble of floristically heterogeneous plantations which renders this agroforestry system valuable for plant diversity conservation, particularly in a region where native forest vegetation has almost disappeared.     

Conservation of Vascular Epiphyte Diversity in Shade Cacao Plantations in the Chocó Region of Ecuador

To assess the contributions of rustic shade cacao plantations to vascular epiphyte conservation, we compared epiphyte species richness, abundance, composition, and vertical distributions on shade trees and in the understories of six plantations and adjacent natural forests. On three phorophytes and three 10 × 10 m understory plots in each of the agroforestry plantations and natural forests, 54 and 77 species were observed, respectively. Individual-based rarefaction curves revealed that epiphyte species richness was significantly higher on forest phorophytes than on cacao farm shade trees; detailed analyses showed that the differences were confined to the inner and outer crown zones of the phorophytes. No differences in epiphyte species richness were found in understories. Araceae, Piperaceae, and Pteridophyta were less species-rich in plantations than in forests, while there were no differences in Orchidaceae and Bromeliaceae. Regression analysis revealed that epiphyte species richness on trunks varied with canopy cover, while abundance was more closely related to soil pH, canopy cover, and phorophyte height. For crown epiphytes, phorophyte diameter at breast height (dbh) explained much of the variation in species richness and abundance. There were also pronounced downward shifts in the vertical distributions of epiphyte species in agroforests relative to natural forests. The results confirm that epiphyte diversity, composition, and vertical distributions are useful indicators of human disturbance and showed that while the studied plantations serve to preserve portions of epiphyte diversity in the landscape, their presence does not fully compensate for the loss of forests.     

Biodiversity and carbon storage are correlated along a land use intensity gradient in a tropical montane forest watershed,Mexico

Tropical montane cloud forest landscapes are changing, and forest conversion to other land uses is a major driver of biodiversity loss. Land use intensification can lead to significant losses in biodiversity and carbon storage (C); however, the impacts may vary greatly depending on land use type, management practices, and environmental context. We investigated how biodiversity and C are related along a gradient of land use intensification characterized by four dominant land uses in the upper part of Antigua River watershed, Mexico. The land uses were montane cloud forest, secondary forest, and traditional and intensive shade coffee plantations. We determined tree species composition, diversity, ecosystem structure, wood density and C content in dominant tree species to assess aboveground biomass (AGB) and C storage within eight study sites across the land use intensity gradient. A total of 83 tree species was recorded. A canonical correspondence analysis indicated that land uses are separated by particular tree species assemblages. Forests had higher basal area, density, and biomass than coffee plantations, however, the traditional shade coffee plantation had values similar to secondary forest. Calculating C using the standard estimate of 50% of AGB resulted in an overestimation of stored C by 5.8 to 4.1% compared to calculations based on actual measurements. Carbon storage in AGB and biodiversity were strongly and positively related across the land use intensity gradient, although the distinction between the two different intensities of coffee plantation management was not consistently as clear as we had expected. Carbon was highest in forest, but secondary forests and traditional shade coffee plantation had similar C, while intensive coffee had the lowest C content. These results highlight the importance of considering the potential of low intensity land uses such as traditional coffee plantations to mitigate biodiversity loss and preserve ecosystem functions as part of conservation efforts.     

Effects of Agricultural Intensification on the Assemblage of Leaf-Nosed Bats (Phyllostomidae) in a Coffee Landscape in Chiapas,Mexico

The agricultural matrix surrounding forested areas serves critical functions as dispersal corridors and alternate habitat for wildlife. Agricultural intensification, however, can reduce the conservation value of these areas. To evaluate the effects of agroecosystem management on bat assemblages, we studied the abundance and diversity of leaf-nosed bats (family: Phyllostomidae) in southwestern Chiapas, Mexico, a landscape dominated by shade coffee agroforestry. During 2104 mist-net hour (MNH), we captured 3167 bats of 27 phyllostomid species. Total species richness in each land-use type varied from 24 species in forest fragments to 22 species in commercial shade polycultures. Although the cumulative observed species richness showed little change in response to management intensity, the number of bats captured per MNH declined significantly in the more intensively managed (i.e., low-shade monocultures) plantations. Intensively managed coffee plantations had lower phyllostomid diversity and species similarity, and had lower proportions of nectarivorous and animalivorous bats. Among frugivores, the proportion of large (>25 g) frugivores captured increased with management intensity. Recapture frequency was significantly higher than expected in forest fragments, and lower than expected in more intensively managed coffee. Our results suggest that less intensively managed coffee agroforests can serve as valuable feeding and commuting areas for most leaf-nosed bats, and that maintaining forest fragments in agricultural landscapes contributes to bat diversity. Declines in populations of gleaning insectivores, however, could compromise natural suppression of insect pests in these agricultural areas.     

Diversity of dung and carrion beetles in a disturbed Mexican tropical montane cloud forest and on shade coffee plantations

This paper analyzes the diversity of dung and carrion beetles (Scarabaeinae and Silphidae) in four human-induced habitats of a disturbed tropical montane cloud forest: polyspecific shade coffee plantations, monospecific shade coffee plantations, tropical montane cloud forest fragments, and clear cuts. The four habitats had similar richness, species composition, and assemblage structure of dung and carrion beetles. Differences were found in abundance and biomass levels for the four dominant species in the landscape. Dung beetles were more abundant than carrion beetles, but the biomass was higher for the latter. Carrion beetles were seasonal, while dung beetles were clearly not. When forest fragments and shade coffee plantations were compared to other similar habitats in the region, the same general pattern was observed. However, forests with high disturbance and monospecific shade coffee plantations had lower species richness than forests with low and medium disturbance and polyspecific shade coffee plantations. Thus shade coffee plantations maintain connectivity between patches of cloud forest in a landscape that is strongly affected by human activities. Protecting landscape diversity appears to ensure high species richness.     

Abundance responses of frugivorous bats (Stenodermatinae) to coffee cultivation and selective logging practices in mountainous central Veracruz,Mexico

Shifting and permanent cultivation, selective logging, cattle production and coffee plantations are among the most important factors in montane cloud forest conversion and disturbance. Although shaded-coffee plantations can contribute to the preservation of local species richness, abundance of organisms could be determined by habitat resource availability in agricultural landscapes. We compared abundance of Sturnira and Artibeus bats (Phyllostomidae, Stenodermatinae), in shade coffee plantations and disturbed cloud forest fragments, which represent habitats with different chiropterochorous plant density. We also investigated the relationship between bat species abundance and food plant richness, abundance and diversity. We captured 956 bats, 76% in cloud forest fragments and 24% in shaded coffee plantations. Abundance of Sturnira spp. (small bats) was greater in cloud forest than in coffee plantations, but Artibeus spp. (large bats) abundance was similar in both habitats. Chiropterochorous plant abundance was positively related with bat abundance for Sturnira spp., while chiropterochorous plant richness and diversity were negatively related for Artibeus spp. This suggests that frugivorous bats with different morphological and ecological characteristics respond differentially to anthropogenic activities. For landscape management purposes, the maintenance and augmentation of diverse food resources, for frugivorous bats with different foraging requirements in coffee plantations, will benefit the resilience of bats to modification of their natural habitat.     

Ferns,frogs, lizards,birds and bats in forest fragments and shade cacao plantations in two contrasting landscapes in the Atlantic forest,Brazil

The traditional shade cacao plantations (cabrucas) of southern Bahia, Brazil, are biologically rich habitats, encompassing many forest-dwelling species. However, a critical question for the conservation management of this specific region, and the highly fragmented Atlantic forest in general, is to what extent the conservation value of cabrucas relies on the presence of primary forest habitat in the landscape. We investigated the relative importance of cabrucas and forests for the conservation of five diverse biological groups (ferns, frogs, lizards, birds and bats) in two contrasting landscapes in southern Bahia, one dominated by forest with some interspersed cabrucas, and one dominated by cabrucas with interspersed forest fragments. The community structure (richness, abundance and diversity) of all biological groups differed between cabrucas and forests, although these differences varied among groups. A high number of forest species was found in the cabrucas. However, there were pronounced differences between the two landscapes with regard to the ability of cabrucas to maintain species richness. Irrespective of the biological group considered, cabrucas located in the landscape with few and small forest fragments supported impoverished assemblages compared to cabrucas located in the landscape with high forest cover. This suggests that a greater extent of native forest in the landscape positively influences the species richness of cabrucas. In the landscape with few small forest fragments interspersed into extensive areas of shade cacao plantations, the beta diversity of birds was higher than in the more forested landscape, suggesting that forest specialist species that rarely ventured into cabrucas were randomly lost from the fragments. These results stress both the importance and the vulnerability of the small forest patches remaining in landscapes dominated by shade plantations. They also point to the need to preserve sufficient areas of primary habitat even in landscapes where land use practices are generally favorable to the conservation of biodiversity.     

Arboreal Ant Abundance and Leaf Miner Damage in Coffee Agroecosystems in Mexico

Shaded coffee agroecosystems traditionally have few pest problems potentially due to higher abundance and diversity of predators of herbivores. However, with coffee intensification (e.g., shade tree removal or pruning), some pest problems increase. For example, coffee leaf miner outbreaks have been linked to more intensive management and increased use of agrochemicals. Parasitic wasps control the coffee leaf miner, but few studies have examined the role of predators, such as ants, that are abundant and diverse in coffee plantations. Here, we examine linkages between arboreal ant communities and coffee leaf miner incidence in a coffee plantation in Mexico. We examined relationships between incidence and severity of leaf miner attack and: (1) variation in canopy cover, tree density, tree diversity, and relative abundance of Inga spp. shade trees; (2) presence of Azteca instabilis, an arboreal canopy dominant ant; and (3) the number of arboreal twig‐nesting ant species and nests in coffee plants. Differences in vegetation characteristics in study plots did not correlate with leaf miner damage perhaps because environmental factors act on pest populations at a larger spatial scale. Further, presence of A. instabilis did not influence presence or severity of leaf miner damage. The proportion of leaves with leaf miner damage was significantly lower where abundance of twig‐nesting ants was higher but not where twig‐nesting ant richness was higher. These results indicate that abundance of twig‐nesting ants in shaded coffee plantations may contribute to maintenance of low leaf miner populations and that ants provide important ecosystem services in coffee agroecosystems.     

Distribution of Ground-dwelling Arthropods in Tropical Countryside Habitats

The future of biodiversity depends to a great extent on the conservation value of human-dominated and semi-natural habitats. In a mixed agricultural landscape in southern Costa Rica, we compared the richness and composition of terrestrial arthropod communities occurring in three habitat types along a gradient of increasing disturbance: in a large (227ha) forest fragment, small (3.8–5.3ha) forest fragments, and sun coffee (1–3ha) plantations. Pitfall trap sampling revealed decreasing morphospecies richness with increasing disturbance. Moreover, the number of species unique to a habitat type was lower in the smaller forest fragments and the coffee sites. We found significant changes in community composition associated with habitat at the levels of order (all arthropods), family (beetles), and morphospecies (carabids, scarabs, and ants). We identified no significant correlation of richness among the taxonomic orders, meaning these taxa are unable to serve as biodiversity indicators (for each other or for all arthropods) in the study region. Arthropod diversity presently found in countryside habitats is certainly lower, and perhaps less sustainable, than that of the extensive forested habitats fragmented < 40 years ago. It nonetheless remains substantial, suggesting a conservation opportunity in human-dominated landscapes of the tropics.     

The contribution of cacao agroforests to the conservation of lower canopy ant and beetle diversity in Indonesia

The ongoing destruction of tropical rainforests has increased the interest in the potential value of tropical agroforests for the conservation of biodiversity. Traditional, shaded agroforests may support high levels of biodiversity, for some groups even approaching that of undisturbed tropical forests. However, it is unclear to what extent forest fauna is represented in this diversity and how management affects forest fauna in agroforests. We studied lower canopy ant and beetle fauna in cacao agroforests and forests in Central Sulawesi, Indonesia, a region dominated by cacao agroforestry. We compared ant and beetle species richness and composition in forests and cacao agroforests and studied the impact of two aspects of management intensification (the decrease in shade tree diversity and in shade canopy cover) on ant and beetle diversity. The agroforests had three types of shade that represented a decrease in tree diversity (high, intermediate and low diversity). Species richness of ants and beetles in the canopies of the cacao trees was similar to that found in lower canopy forest trees. However, the composition of ant and beetle communities differed greatly between the agroforest and forest sites. Forest beetles suffered profoundly from the conversion to agroforests: only 12.5% of the beetle species recorded in the forest sites were also found in the agroforests and those species made up only 5% of all beetles collected from cacao. In contrast, forest ants were well represented in agroforests, with 75% of all species encountered in the forest sites also occurring on cacao. The reduction of shade tree diversity had no negative effect on ants and beetles on cacao trees. Beetle abundances and non-forest ant species richness even increased with decreasing shade tree diversity. Thinning of the shade canopy was related to a decrease in richness of forest ant species on cacao trees but not of beetles. The contrasting responses of ants and beetles to shade tree management emphasize that conservation plans that focus on one taxonomic group may not work for others. Overall ant and beetle diversity can remain high in shaded agroforests but the conservation of forest ants and beetles in particular depends primarily on the protection of natural forests, which for forest ants can be complemented by the conservation of adjacent shaded cacao agroforests.