Effects of Season and Vegetation Type on Community Organization of Dung Beetles in a Tropical Dry Forest1

Dung beetles are important components of most terrestrial ecosystems. In tropical rain forests, dung beetle communities can be very rich in number of species and individuals, and they are known to be useful bioindicators of habitat disturbance. In contrast, very little is known about the organization of dung beetle communities in tropical dry forests. The aim of this study was to describe in detail the dung beetle community of a Mexican tropical dry forest and to assess the relative importance of rainfall seasonality and forest structure in affecting the temporal and spatial dynamics of this community. Dung beetles were captured with pitfall traps at the beginning of the rainy season, the middle of the rainy season, and the middle of the dry season, in two distinct forest types: deciduous forest (DF) and semideciduous forest (SDF) at the Estación de Biología Chamela. Both rainfall seasonality and forest structure affected the community organization of dung beetles. During both rainy periods, 14 species were captured, but only three during the dry season. Dung beetles captured during the dry season were only found in the SDF. When comparing the beginning and the middle of the rainy season, differences in abundance and guild structure were also observed between both periods and between forest types, but these differences were much less pronounced.     

Effects of Degradation and Replacement of Southern Brazilian Coastal Sandy Vegetation on the Dung Beetles (Coleoptera: Scarabaeidae)

In this paper we address the effects of anthropogenic disturbance and replacement of Brazilian Coastal sandy vegetation (restingas) on dung beetles communities. We sampled dung beetles in the four main vegetative physiognomies of Guriri Island, Espírito Santo State: forest restinga, restinga Clusia, disturbed restinga (from burning events), and pastures. We placed four sets of two pitfall traps (baited with horse and human dung) in four independent areas of each vegetation type, and collected 14,534 individuals of 13 dung beetle species. Neither log₁₀ of individuals nor log₁₀ of species richness were good predictors of restinga disturbance. However, a significant amount of variation in dung beetle abundance and richness could be explained by bait type. Ordination of these sites using hybrid multidimensional scaling revealed a gradient of habitat disturbance from undisturbed restinga samples to pasture. Dung beetle communities along this gradient demonstrated a complete turnover in species composition, from restinga‐specialists to invasive and generalists species respectively. This complete turnover signals the local extirpation of forest‐adapted species in disturbed and converted areas. Only a single dung beetle species in preserved restingas is protected by Brazilian law (Dichotomius schiffleri). Given the extent of the clearing of restinga habitat, the conservation status of dung beetles associated with restinga forest gives cause for concern.     

Fire? They don't give a dung! The resilience of dung beetles to fire in a tropical savanna

1. Disturbance is a strong driver of community assembly and fire has long been recognised as one of the main disturbances of terrestrial ecosystems. This study tested the resilience of dung beetles to fire events in campos rupestres, which is a tropical savanna ecosystem that evolved under a frequent fire regime, by assessing the resistance and recovery of their communities. 2. Dung beetles were sampled before and after a fire event and the effect of fire on dung beetle richness, abundance, mean community biomass and composition was tested. The effects of time since last fire and fire frequency on the community were also tested. 3. No effect of fire occurrence, time since last fire and fire frequency on any community variable was found. 4. Some non‐mutually exclusive mechanisms promoting the resistance and recovery of dung beetles in campos rupestres could be acting in synergy. One potential mechanism is the mismatched seasonality between fire events and dung beetle occurrence, as fires occur during the dry season and dung beetles are present above ground during the rainy season. Furthermore, dung beetles are insects that remain buried during most of their lifetime, which could protect individuals from being burned. Another potential mechanism is the replacement of species in burned areas by the movement of individuals from unburned areas, attracted by resources and/or by metacommunity dynamics. 5. It is concluded that in this ‘fire‐dependent’ ecosystem, dung beetle communities are resilient to fire and seem not to be structured by this disturbance.     

Does natural reforestation represent a potential threat to dung beetle diversity in the Alps?

Traditional agro-pastoral practices are in decline over much of the Alps, resulting in the complete elimination of livestock grazing in some areas. Natural reforestation following pastoral abandonment may represent a significant threat to alpine biodiversity, especially that associated with open habitats. This study presents the first assessment of the potential effects of natural reforestation on dung beetles by exploring the relationships between the beetle community (abundance, diversity, species turnover and assemblage structure) and the vegetation stages of ecological succession following pastoral abandonment. A hierarchical sampling design was used in the montane belt of the Sessera Valley (north-western Italian Alps). Dung beetles were sampled across 16 sampling sites set in four habitat types corresponding to four different successional stages (pasture, shrub, pioneer forest and beech forest) at two altitudinal levels. The two habitats at the extremes of the ecological succession, i.e. pasture and beech forest, had the greatest effect on the structure of local dung beetle assemblages. Overall, dung beetle abundance was greater in beech forest, whereas species richness, Shannon diversity and taxonomic diversity were significantly higher in pasture, hence suggesting this latter habitat can be considered as a key conservation habitat. Forests and pastures shared a lower number of species than the other pairs of habitats (i.e. species turnover between these two habitats was the highest). The two intermediate seral stages, i.e. shrub and pioneer forest, showed low dung beetle abundance and diversity values. Local dung beetle assemblages were also dependent on season and altitude; early-arriving species were typical of pastures of high elevation, whereas late-arriving species were typical of beech forests. It is likely that grazing in the Alps will continue to decrease in the future leading to replacement of open habitats by forest. This study suggests therefore that, at least in the montane belt, reforestation may have potentially profound and negative effects on dung beetle diversity. Maintaining traditional pastoral activities appears to be the most promising approach to preserve open habitats and adjacent beech forests, resulting in the conservation of species of both habitats.     

Space-for-time substitution reveals a hump-shaped distribution of dung beetles

Unraveling how climate change impacts the diversity and distribution patterns of organisms is a major concern in ecology, especially with climate-sensitive species, such as dung beetles. Often found in warmer weather conditions, beetles are used as bio-indicators of environmental conditions. By using an altitudinal gradient as a proxy for climate change (i.e., space-for-time substitution), we assessed how changes in climatic variables, such as temperature and precipitation, impact patterns of dung beetle diversity and distribution in the Peruvian Andes. We recorded dung beetle diversity using three different types of baits, feces, carrion, and fruits, distributed in 18 pitfall traps in five different altitudinal sites (from 900 to 2500 m, 400 m apart from each other) in the rainy and dry season. We found that (i) dung beetle richness and abundance were influenced by the climate gradient, (ii) seasonality influenced beetle richness, which was high in the wet season, but did not influence abundance, (iii) dung beetle richness and abundance fit to a hump-shaped distribution pattern along the altitudinal gradient, and (iv) species richness is the beta-diversity component that best describes the composition of dung beetle species along the altitudinal gradient. Our data show that the distribution and diversity of dung beetles are different at larger scales, with different patterns resulting from the response of species to both abiotic and biotic factors.     

Factors influencing duiker dung decay in north‐east Gabon: are dung beetles hiding duikers?

We analysed seasonality of dung decay time and the influence of rainfall, leaf fall, beetle attack and moisture on dung decay. Our study was carried out at the Ipassa Reserve, north-east Gabon. We compared the seasonality of dung decay with the seasonality of dung beetle abundance and guild structure. Dung beetle activity was the main factor influencing dung decay in our study site. Decay time was the highest during the main dry season (3.4 days) and the lowest during the short rainy season (0.7 days). Dung decay time was closely related to dung beetle abundance, especially to the abundance of nocturnal beetles. We discuss the implications of such results for duiker survey methods based on dung pellet counts in areas where decay time is extremely short or unknown.     

Dung beetles in a Central Amazonian rainforest and their ecological role as secondary seed dispersers

Abstract 1. The role of several factors that affect the composition of the dung beetle assemblages in an Amazonian rainforest was quantified, together with the effect of these factors on the role that dung beetles play as secondary seed dispersers. 2. A total of 61 dung beetle species was captured during 3360 h of trapping. During nocturnal trapping periods, more dung beetles, of larger mean size, and more species were captured per trap than during diurnal trapping periods. 3. During the rainy season, more dung beetle species were captured per trap than during the dry season, but the number of individuals and their mean size did not vary between seasons. 4. Bait size had a significant effect on the mean number of beetles and mean number of species but not on mean beetle size. As bait size increased from 5, 10, 25, to 50 g, more beetles and more species were captured per trap. 5. Between 6 and 73% of plastic beads, used as seed mimics, were buried by dung beetles at depths that ranged from 0.5 to 7 cm. Both the proportion of beads buried and burial depth decreased with increasing bead size, and increased with increasing amounts of dung surrounding each bead (5, 10, and 25 g). 6. The proportion of buried seeds for three species varying in size between 5 and 27 mm, increased with increasing dung beetle size, using beetles of seven sizes, varying between 10 and 25 mm. 7. Seeds surrounded by dung were buried more often and more deeply when placed on the forest floor during the late afternoon than when placed during the early morning. Seeds were also buried more often when placed on the forest floor during the rainy season than when placed during the dry season, but season had no effect on burial depth. 8. Forests in Central Amazonia hold a rich dung beetle community that plays an active role in secondary seed dispersal, and consequently in plant regeneration. The interaction between seeds and beetles is complex because it is affected by many factors.     

Is microclimate-driven turnover of dung beetle assemblage structure in regenerating coastal vegetation a precursor to re-establishment of a forest fauna?

We questioned the capability of post-mining rehabilitation and successional changes in coastal vegetation to achieve restoration of dune forest, dung beetle assemblages in the Maputaland Centre of Endemism, South Africa. A repeat 2010 study of structural turnover between dung beetle assemblages across a 33 year successional sere of rehabilitating vegetation and old-growth forest (>73 years) produced comparable results to an earlier study across the 23 year chronosequence of 2000. Despite overlap, three structural patterns along the 33 year chronosequence were associated with specific stages of vegetation succession and their characteristic microclimates as in 2000. Although species biased to unshaded habitat dominated the earliest succession, there was rapid re-establishment of dominance by shade-associated forest species. In concert with progression from unshaded, post-mining vegetation to strongly shaded, early successional, Acacia shrub-woodland, there was an initial increase in similarity of the dung beetle fauna (species-poor, low abundance) to that in strongly-shaded forest (also species-poor, low abundance). However, in concert with decreasing shade cover in late successional woodland, the dung beetle fauna became species-rich with high abundance so that the early successional trajectory of increasing similarity to forest fauna either levelled off to a plateau (species in 2000; abundance in 2010) or declined (species in 2010, abundance in 2000). It remains to be seen if gaps forming in the oldest Acacia woodland permit forest tree saplings of the exposed understorey to recreate a forest canopy that would be tracked by dung beetles to re-establish a typically species-poor, deep shade, forest assemblage with low abundance.     

Tamarins and Dung Beetles: An Efficient Diplochorous Dispersal System in the Peruvian Amazonia

Dung beetles fulfill several key functions in ecosystems but their role as secondary seed dispersers is probably one of the most complex ones. Various factors, such as seed characteristics, dispersal pattern induced by the primary disperser, season, and habitat, can affect the seed–beetle interaction. Particularly little is known about the fate of seeds primarily dispersed in small feces. The aim of this study was to investigate the effects of these factors on the dung beetle community (species composition, number and size of individuals) and its consequences on burial occurrence and depth of seeds primarily dispersed by two tamarin species. We captured dung beetles in a Peruvian rain forest with 299 dung‐baited pitfall traps to characterize the dung beetle community. Seed burial occurrence and depth were assessed by marking in situ 551 dispersed seeds in feces placed in cages. Among these seeds, 22.5 percent were buried by dung beetles after 2 d. We observed a significant effect of the amount of dung, season, time of deposition, and habitat on the number of individuals and species of dung beetles, as well as on seed burial occurrence and depth, while the tamarin species significantly influenced only the number and the size of dung beetles. This seed dispersal loop is particularly important for forest regeneration: small to large seeds dispersed by tamarins in secondary forest can be buried by dung beetles. These seeds can thus benefit from a better protection against predation and a more suitable microenvironment for germination, potentially enhancing seedling recruitment.     

Forest complexity drives dung beetle assemblages along an edge-interior gradient in the southwest Amazon rainforest

1. The habitat heterogeneity hypothesis predicts that heterogeneous habitats may provide more niches and diverse ways of exploiting environmental resources, thereby allowing more species to coexist, persist and diversify. 2. We aimed to investigate how an edge-interior gradient related to forest complexity influences species composition, abundance and richness of dung beetles in the western Amazon rainforest. We expected dung beetle abundance and richness to increase along the forest edge-interior gradient, in accordance with the habitat heterogeneity hypothesis. We also expected strong changes in species composition driven by species turnover in the forest interior and nestedness along the forest edges. We sampled dung beetles using baited pitfall traps across an edge-interior gradient. We also assessed the variation in forest features along the edge-interior gradient to identify changes in forest complexity. 3. Both species richness and abundance of dung beetles increased along the forest edge-interior, following the gradient of forest complexity. The Sorensen dissimilarity of dung beetle assemblages was higher among sampling units placed near the forest edge, although neither turnover, nor nestedness was different between the extremes of the forest edge-interior gradient. There was a clear compositional change along the edge-interior gradient mostly driven by species turnover. Individual indicator value analysis revealed that species were strongly associated with the forest interior conditions. 4. The simplification of the Amazon rainforest near clearings causes compositional changes in dung beetle assemblages. These changes are characterised by species-poor and low-abundance assemblages and may impair dung beetle ecological functions and therefore forest recovery.     

Leaf-cutting ant nests support less dense and impoverished seed assemblages in a human-modified Caatinga dry forest

Regenerating forests make up an increasingly large portion of tropical landscapes worldwide and regeneration dynamics may be influenced by leaf-cutting ants (LCA), which proliferate in disturbed areas and collect seeds for fungus culturing. Here, we investigate how LCA influences seed fate in human-modified areas of Caatinga dry forest. We evaluate the seed deposition and predation on Atta opaciceps nests, foraging habitat surrounding nest and control habitat away of nest influence of 15 colonies located along a forest cover gradient during the rainy and dry seasons. For each habitat, four 50-cm² plots were established and all seeds on the soil surface were collected along 1 year. We recorded 13,628 seeds distributed among 47 species and 36.57% of the total seeds did not show any sign of predation. Nest mound habitats supported low-density and species-poor seed assemblages, which were taxonomically distinct from the control habitats. These effects only occurred in the rainy season. The proportion of undamaged seeds were similar across the habitats. While forest cover did not influence seed assemblage in terms of species richness or seed predation, it did interact with habitat type via increments in seed abundance as forest cover increased across the nests. Forest cover also affected seed composition, but only in the rainy season. These results indicate that LCA decrease seed deposition in areas under their influence, particularly on the nest mounds. As LCA profit from human disturbance in the Caatinga, their role as seed ‘sinks’ should be enhanced in disturbed Caatinga patches, particularly during the rainy season, when most of the plant recruitment occurs. Our findings reinforce the importance of LCA as drivers of forest dynamics and resilience in human-modified landscapes.     

Riparian Areas and Conservation of Herpetofauna in a Tropical Dry Forest in Western Mexico

Studies that assess the importance of riparian habitats in maintaining diversity of herpetofaunal assemblages in tropical dry forests are limited. We examined changes in abundance, diversity and composition of anuran, lizard and snake assemblages along stream edge–upslope gradients in conserved and disturbed areas of tropical dry forest on the Pacific coast of México. We sampled 659 plots in six watersheds over 2 yr. Two forest conditions (conserved and human disturbed, with three watersheds as replicates) were evaluated in the dry and rainy season. Within each watershed, plots were randomly located at three different distance categories from either stream edge: 0–10 m (near‐stream environment), 30–40 m (mid‐slope environment), and 50–60 m (upslope environment). Herpetofauna was surveyed by time‐constrained searches with a sampling effort of 1980 person‐hours. Eighteen anuran, 18 lizard and 23 snake species were recorded. Overall, abundance and diversity of lizards and snakes decreased from near‐stream to upslope areas in both forest conditions and seasons; while that of anurans followed this trend only for the conserved forest during the rainy season. Regardless of distance, abundance and diversity of anurans markedly decreased during the dry season, while that of snakes and lizards increased. Overall, our study shows that the importance of riparian areas for herpetofaunal conservation in dry tropical forests varies with forest condition and season.     

Changes in the dung beetle community in response to restinga forest degradation

Restinga (forest formations on sandy substrates on the Brazil Atlantic coast) have declined from covering approximately 80 % of the coastline and continue to do so due to anthropogenic activity. This study compares the abundance, richness and species composition of conserved (CR) and degraded (DR) resting forest. We used six locations on the coast of Pernambuco, Brazil where there were paired CR and DR sites and used baited pitfall traps to sample dung beetles in the dry and wet seasons. We captured 1,724 individuals, which belonged to 25 species and 10 genera; 1,030 individuals (15 species) were from CR and 694 individuals (17 species) from DR. No significant differences was observed in the patterns of species richness or abundance between CR and DR sites but non-metric multidimensional scaling and similarity analyses revealed differences in species composition between CR and DR sites. Additionally DR sites had a higher beta diversity than CR sites. We found only seven of the 25 species identified in this study in both areas, indicating that few species from the original ecosystem remain in degraded sites. In addition, the forest species that were recorded in Degraded sites, such as Canthon nigripenne and Dichotomius schiffleri, had low abundance when compared to conserved restinga. We suggest that parts of the CR become areas under legal protection, in order to maintain the biodiversity of the remaining areas of restinga.     

Dung beetle persistence in human-modified landscapes: Combining indicator species with anthropogenic land use and fragmentation-related effects

Identifying and making use of ecological indicators becomes an essential task in the conservation of tropical systems, mainly in fragmented landscapes where land use intensification and habitat loss are confounding factors in the detection of species’ responses to human-caused disturbance. We aimed to analyze the importance of anthropogenic land use and fragmentation-related effects on dung beetle (Coleoptera: Scarabaeinae) persistence according to the interior–exterior non-linear gradient (forest + matrix) in a fragmented Atlantic Forest landscape used to sugar cane production and cattle ranching/farming. We offer scores for a comprehensive set of community-level attributes, from beetle abundance to taxonomic and ecological composition (i.e. species body size), including a list of indicator species of different forest habitats and adjacent matrix. Dung beetles were surveyed by traps across forest interiors (i.e. core forest areas) and edges of a primary forest, small fragments, sugar cane fields and pastures in a total of 60 sites. Indicator analyses were conducted across the landscape, using two well-established methods (IndVal and SIMPER). Our results suggest that (1) cross-habitat taxonomic distinctness is associated with the presence of indicator species, (2) some species benefit or are dependent of open habitats created by human-disturbances, such as forest edges (e.g. Canthon nigripennis) and matrices (e.g. Canthon aff. piluliformis, Dichotomius nisus and Trichilum externepunctatum), (3) although landscape habitats exhibit reduced beta diversity, dung beetle assemblages are spatially organized in response to the presence of both forest habitats and matrix and fragment area, (4) forest interior supports beetle assemblages biased toward large-bodied species, (5) accordingly forest interior, forest edges and matrix support taxonomically distinct assemblages, both contributing to the bulk of species richness at landscape level, (6) the response of dung beetles to the interior–exterior non-linear gradient (i.e. forest edge + matrix) reveals a similar pattern regardless of the nature of the matrix, and (7) there is no within-habitat variation in beetle abundance and species richness associated with distance from forest edge. Given that there is a high number of forest-dependent or forest-interior specialist species (e.g. Aphengium aff. sordidum, Ateuchus aff. alipioi, Dichotomius mormon, Ontherus aff. erosus and Onthophagus aff. clypeatus) dung beetle persistence in human-modified landscape is highly dependent on the presence of core areas, although edge-affected and matrix habitats may be complementary. This information is essential to permit a better prospect for dung beetle persistence in human-modified landscapes as they continue to move toward edge-dominated landscapes with intensively managed matrices.     

Invasion and retreat: shifting assemblages of dung beetles amidst changing agricultural landscapes in central Peru

This study examines the effects of deforestation, and the habitat value of coffee and regenerated forest for tropical dung beetles, a functionally significant insect group. Pitfall trapping was conducted at 22 sites in a montane region of central Peru during April and November/December of 2002. Sites included primary and secondary forest, shade-coffee, regenerated forest and open farms (mainly with banana, yuca, and corn). Ordination techniques indicated that beetle assemblages in forests, regenerated forest and coffee were relatively similar. However, assemblage compositions in forested areas differed even at similar altitudes under the influence of biogeographical factors, and the assemblages at disturbed sites (farms/coffee) were influenced by beetle dispersal from adjacent forests. During dry months, when beetle activity is low, communities at all habitat types tended to converge because fewer unique species were recorded in forests at that time and habitat/season generalists were dominant. Preliminary results also indicate that beetles in shady crops such as bananas responded to plant growth: as the banana canopy closed-in, producing more shade, open-habitat specialists retreated and forest/shade specialists invaded the sites. Chronosequence data at two of the sites demonstrate the rapid and dramatic changes in species richness and assemblage composition caused by deforestation. As forests become increasingly fragmented, and open farms continue to expand, dung beetles will become more restricted to the remaining fragments and reserves. In the mosaic landscape studied here, shade crops, like coffee, act as habitat and corridors for many dung beetle species. Small farm size and the consequent magnitude of edge effects, likely contributed to beetle movement between habitat types and determined the apparent generalist nature of many of the dung beetle species in this study.     

Response of the dung beetle community to different climatic zones: Does the land use system matter?

The conversion of Brazilian savanna into exotic pastures leads to the loss of dung beetles and a decrease in their contribution to ecological functions. We hypothesized that the dung beetle communities from exotic pastures would show greater significant differences between climatic zones, when contrasted to communities from Brazilian savanna in the same region, since dung beetle assemblages in pastures are more simplified. We assessed which variables (purpose of production, type of management, percentage the habitat per buffer, soil penetration resistance, pasture area and herd size) affect more the dung beetle community in exotic pastures. We carried out this study in 48 areas of native Brazilian savannas and exotic pastures distributed across four bioclimatic zones: BZ1, hot with three dry months; BZ2, hot with 4–5 dry months; BZ3, sub-hot with 4–5 dry months and BZ4, meso-thermal with 4–5 dry months of Minas Gerais State, Brazil. In each BZ, six areas of Brazilian savannas and six areas of exotic pasture were selected. In the Brazilian savanna areas, the species richness, abundance and biomass of dung beetles did not differ between the bioclimatic zones, unlike the exotic pastures. The composition of the dung beetle community was different between land use systems and between bioclimatic zones; the interaction between the two factors was also significant. Our results provide evidence that dung beetle communities active in exotic pastures are more susceptible to climatic environmental variations than communities from more complex and stable habitats, such as savannas. Finally, the best model suggested that all the six variables combined explained about 91% of the total variability in species composition observed between sampling sites.     

Roles of environmental variables and land usage as drivers of dung beetle assemblage structure in mopane woodland

Colophospermum mopane woodland covers large areas of dry lowland savanna in southeastern Africa. Dominant land usage is conservation (45%) with the remainder mostly modified by farming. Dung beetle responses to environment (dung type, habitat, weather) and land usage (conservation, farming, mining) were examined at Phalaborwa (23.9431°S 31.1411°E) in the Phalaborwa‐Timbavati Mopaneveld, South Africa. Partitioning of gamma species richness and diversity showed lower alpha values in mine areas than in farm and conserved areas. However, between‐land usage differences in species richness, alpha diversity, abundance and biomass, showed lower significance than those between dung type and different weather. At two sampling scales, three multivariate techniques variously separated assemblages according to land usage, dung type and weather. Analysis of 21 mean samples separated clusters according to dung type (Canonical Correspondence Analysis, CCA) or mine assemblages, conserved plus farm assemblages on pig plus elephant, or cattle dung (NMDS, Factor Analysis) with shared variance of >80% and unique variance of 16–18% per cluster. In analysis of 188 samples (CCA), each overlapping dung type cluster was offset in ordinal space with congruent patterns of separation according to land usage and weather (drier days distant from moister days; conserved plus farm areas distant from early succession mine areas, which were distant from disturbed and later succession mine areas). Mining, dung types, and moist conditions were the strongest contributors to between‐assemblage differences. Compared with conserved areas, dung beetle diversity is appreciably altered by mining but only slightly altered by intensive game farming or livestock ranching with subsistence agriculture.     

Abrupt species loss of the Amazonian dung beetle in pastures adjacent to species-rich forests

Anthropogenic disturbances, such as conversion of forests to pastures, are considered one of the major causes of Amazonian biodiversity loss. Pastures are hostile environments for forest species that are not adapted to the adverse conditions of open areas. The aim of this study was to analyze the effects of forest replacement by cattle pastures in the north-eastern part of the Amazonian rainforest using dung beetles (Scarabaeidae: Scarabaeinae) as indicators. Therefore, we determined edge effects and differences in dung beetle species richness, composition, and abundance between forest and neighbouring cattle pastures. A total of 6723 individuals of 63 species of dung beetle were collected. In comparison to forests, adjacent pastures were sharply less rich and abundant in dung beetles. The forests had 6604 individuals and 59 species, while the pastures had 119 individuals and 12 species. The replacement of forests by pastures results in an increase of dung beetle species turnover. Only 12% of dung beetle species were shared by both forest and pasture environments. We highlight that most Amazonian dung beetles are forest species sensitive to abrupt human-driven modification of habitats and are only moderately affected by edge effects.     

Forest cover and heterogeneous pastures shape the diversity of predatory rove beetles in tropical riparian habitats

In tropical landscapes, forest remnants have been reduced to narrow strips of vegetation along rivers and streams surrounded by agricultural land that affects biodiversity, depending on the habitat and landscape characteristics. To assess the effect of riparian forest loss on the diversity of Staphylininae predatory rove beetles, we considered two habitat conditions (river sites with riparian vegetation and sites with heterogeneous pastures) within two micro-basin types (with >70% and <40% forest cover) in a tropical montane cloud forest landscape, Mexico. Beetles were collected using baited pitfall traps during the rainy season of 2014. No differences were found between micro-basin types and, although species richness (⁰D) was similar between habitat conditions, when the diversity of common (¹D) and dominant (²D) species was considered, sites with heterogeneous pastures were almost twice as diverse as those with riparian vegetation. All diversity measurements were greater in sites with heterogeneous pastures of either micro-basin type. Air temperature and canopy cover were the environmental variables that best explained the variation in beetle species composition. The greatest environmental differences related to species composition were detected between habitat conditions and were more evident in sites with heterogeneous pastures and low forest cover in the surroundings. The results suggest that replacing riparian vegetation with heterogeneous pastures, within micro-basins that lost between 30% and 60% of their forest cover, does not significantly reduce the diversity of predatory rove beetle but rather modifies the beetle composition. Effective formulation of management strategies to mitigate the impact of land use modification therefore requires an understanding of the interaction between vegetation remnants and landscape characteristics.     

Changes of dung beetle communities from rainforests towards agroforestry systems and annual cultures in Sulawesi (Indonesia)

Little is known about how tropical land-use systems contribute to the conservation of functionally important insect groups, including dung beetles. In a study at the margin of Lore Lindu National Park (a biodiversity hotspot in Central Sulawesi, Indonesia) dung-beetle communities were sampled in natural forest, young secondary forest, agroforestry systems (cacao plantations with shade trees) and annual cultures (maize fields), each with four replicates (n = 16 sites). At each site we used 10 pitfall traps, baited with cattle dung, along a 100 m transect for six 3-day periods. The number of trapped specimens and species richness at the natural forest sites was higher than in all land-use systems, which did not significantly differ. Each land-use system contained, on average, 75% of the species richness of the natural forest, thereby indicating their importance for conservation. However, a two-dimensional scaling plot based on NESS indices (m = 6) indicated distinct dung beetle communities for both forest types, while agroforestry systems and annual cultures exhibited a pronounced overlap. Mean body size of dung beetles was not significantly influenced by land-use intensity. Five of the six most abundant dung beetle species were recorded in all habitats, whereas the abundance of five other species was significantly related to habitat type. Mean local abundance and number of occupied sites were closely correlated, further indicating little habitat specialisation. The low dung beetle diversity (total of 18 recorded species) may be due to the absence of larger mammals in Sulawesi during historical times, even though Sulawesi is the largest island of Wallacea. In conclusion, the dung beetle fauna of the lower montane forest zone in Central Sulawesi appears to be relatively robust to man-made habitat changes and the majority of species did not exhibit strong habitat preferences.