Dung Beetle Biomass Research Articles

Functional consequences of animal community changes in managed grasslands: An application of the CAFE approach.

In the midst of an ongoing biodiversity crisis, much research has focused on species losses and their impacts on ecosystem functioning. The functional consequences (ecosystem response) of shifts in communities are shaped not only by changes in species richness, but also by compositional shifts that result from species losses and gains. Species differ in their contribution to ecosystem functioning, so species identity underlies the consequences of species losses and gains on ecosystem functions. Such research is critical to better predict the impact of disturbances on communities and ecosystems. We used the "Community Assembly and the Functioning of Ecosystems" (CAFE) approach, a modification of the Price equation to understand the functional consequences and relative effects of richness and composition changes in small nonvolant mammal and dung beetle communities as a result of two common disturbances in North American prairie restorations, prescribed fire and the reintroduction of large grazing mammals. Previous research in this system has shown dung beetles are critically important decomposers, while small mammals modulate much energy in prairie food webs. We found that dung beetle communities were more responsive to bison reintroduction and prescribed fires than small nonvolant mammals. Dung beetle richness increased after bison reintroduction, with higher dung beetle community biomass resulting from changes in remaining species (context-dependent component) rather than species turnover (richness components); prescribed fire caused a minor increase in dung beetle biomass for the same reason. For small mammals, bison reintroduction reduced energy transfer through the loss of species, while prescribed fire had little impact on either small mammal richness or energy transfer. The CAFE approach demonstrates how bison reintroduction controls small nonvolant mammal communities by increasing prairie food web complexity, and increases dung beetle populations with possible benefits for soil health through dung mineralization and soil bioturbation. Prescribed fires, however, have little effect on small mammals and dung beetles, suggesting a resilience to fire. These findings illustrate the key role of re-establishing historical disturbance regimes when restoring endangered prairie ecosystems and their ecological function.

Estimation of biomass of dung beetles (Coleoptera: Scarabaeoidea) from the Russian Far East

Data on dry biomass and body length are given for 47 species of dung beetles from the southern part of the Russian Far East. The length-to-body weight relation in specimens of 47 species of dung-beetles was calculated, to enable biomass to be estimated from information about body length. Shown, the selection of optimal models of length-weight relationship of dung-beetles depends on the types of trophodynamic relationships of beetles and its size classes. When conducting ecological studies using such an indicator as dry biomass, it is necessary to determine the biomass of individual species from regional faunas, and to determine the biomass along the length of the body of beetles, it is necessary to use exclusively models built also for regional faunas.

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

AbstractThe 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.

Negative effects of forest gaps on dung removal in a full-factorial experiment.

Ecosystem functioning may directly or indirectly-via change in biodiversity-respond to land use. Dung removal is an important ecosystem function central for the decomposition of mammal faeces, including secondary seed dispersal and improved soil quality. Removal usually increases with dung beetle diversity and biomass. In forests, dung removal can vary with structural variables that are, however, often interrelated, making experiments necessary to understand the role of single variables on ecosystem functions. How gaps and deadwood, two main outcomes of forest management influence dung removal, is unknown. We tested if dung removal responds to gap creation and deadwood provisioning or if treatment effects are mediated via responses of dung beetles. We expected lower removal rates in gaps due to lower dung beetle biomass and diversity. We sampled dung beetles and measured dung removal in a highly-replicated full-factorial forest experiment established at 29 sites in three regions of Germany (treatments: Gap, Gap + Deadwood, Deadwood, Control). All gaps were experimentally created and had a diameter of around 30 m. Dung beetle diversity, biomass and dung removal were each lower in gaps than in controls. Dung removal decreased from 61.9% in controls to 48.5% in gaps, irrespective of whether or not the gap had deadwood. This treatment effect was primarily driven by dung beetle biomass but not diversity. Furthermore, dung removal was reduced to 56.9% in the deadwood treatment. Our findings are not consistent with complementarity effects of different dung beetle species linked to biodiversity-ecosystem functioning relationships that have been shown in several ecosystems. In contrast, identity effects can be pronounced: gaps reduced the abundance of a large-bodied key forest species (Anoplotrupes stercorosus), without compensatory recruitment of open land species. While gaps and deadwood are important for many forest organisms, dung beetles and dung removal respond negatively. Our results exemplify how experiments can contribute to test hypotheses on the interrelation between land use, biodiversity and ecosystem functioning.

Replacing native mammal assemblages with livestock in African savannahs, impacts dung beetle diversity and reduces body size

Replacement of complex assemblages of native mammal fauna with livestock species reduces niche heterogeneity. This negatively affects taxa such as dung beetles, which depend on them and can, in turn, affect ecosystem functioning. We assessed the response of dung beetle diversity, biomass and body condition to cattle-farming pressures in protected areas (PAs) and adjacent farms in the savannah biome of northern Namibia. We hypothesized that rich native mammal assemblages are essential to maintain dung beetle diversity and overall biomass. We further explored whether the low-quality dung resources on farms would lead to a decrease in individual body size for species found on both farms and PAs. Overall dung beetle richness increased with higher mammal richness but not relative abundance, demonstrating that a rich native vertebrate assemblage promotes dung beetle richness. Overall dung beetle biomass was lower on farms, but abundance showed no difference. Large-bodied dung specialist species, which are known to be functionally superior, were absent on farms while smaller generalist species proliferated. Furthermore, a large proportion of individuals of species common to both farms and PAs were physically smaller on farms, indicating reduced body condition. Our results show that a high diversity of native mammals maintains dung beetle diversity and higher biomass on PAs. A decrease in native dung on farms leads to reduced body mass, likely negatively impacting ecological function. These results suggest that the conservation of dung beetles and their functions in the expansive African savannah ecosystems is dependent on a complex mix of native mammal species.

Changes in land use affect dung beetle communities but do not affect ecosystem services in the Cerrado of Central Brazil

1. Changes in land use have been identified as one of the main drivers of global biodiversity loss, and also negatively affect ecosystem services. Dung beetles are capable of providing a variety of ecosystem services and can be used as bioindicators.2. We assess whether the land use changes of the Cerrado areas for agricultural purposes (pasture and soybean crops) affects dung beetle community and the associated ecosystem services (dung removal and secondary seed dispersal) provided by dung beetles on their diversity in the Federal District, Brazil.3. A total of 32 261 individuals (Scarabaeinae, Aphodiinae and Anaidinae) were collected. The abundance and biomass of dung beetles were significantly higher in soybean (n = 19 354; biomass = 1145.4 g) and pasture (n = 9865; biomass = 753.6 g) compared to cerrado (n = 3042; biomass = 311.6 g). Sixty‐one species were collected in the cerrado, 58 in soybean and 56 in pasture, most species were paracoprids (52–60%), but no significant differences were observed for the species richness and diversity indices among the different land use systems. The structure of the dung beetle community in areas of the cerrado was distinct from that in pasture and soybean areas, and the latter two were similar. The land use systems did not affect the ecosystem services provided by dung beetles.4. Our results showed that the Cerrado dung beetle community was unique and specific, indicating an imperative need for its preservation, due to its intrinsic value and its importance for the functioning of the ecosystem.

Diversity and resource selection of dung beetles in a relictual mountain forest in Brazil

Most of the tropical ecosystems are now altered, consequently modifying the species diversity, composition and feeding behaviours. Precisely, the survival of species is dependent on their characteristics to endure the novel environments immersed in human-dominated landscapes. Thus, comparative studies of how different community attributes and trophic guilds respond to changes in land use would be useful. In this study, we analyzed diversity, composition and food selection of dung beetles in an Atlantic forest enclave (Ombrophilous forest remnant) from North-eastern Brazil. We sampled dung beetles using 60 pitfall traps distributed in our study region. Diversity and composition were estimated by using Hill numbers (or the effective number of species) and biomass of individuals and were compared among three types of vegetation structure (forest, forest edge and open pastures) and four different types of baits (human, pig, chicken and cattle excrements). We found that diversity measures weighted by biomass allowed better detection of the variation between habitat types and food preference than weighted by the number of individuals. The dung beetle biomass indicates that the spatial dominance of open pastures promote a drastic impoverishment of dung beetle diversity and composition. We also found that β diversity shows an evidence of homogenization on the resource food selection, related with the preference in the attraction of dung beetles to exotic omnivores. Our results show that replacing forests with cattle pastures modifies diversity, species composition, and resource food selection patterns, which could affect the ecosystem provision by dung beetles. Despite our study region is immersed in a human-dominated-landscape, forest remnants continue to hold a high diversity assemblage compared with most degraded environments.

Carbon Neutral: The Failure of Dung Beetles (Coleoptera: Scarabaeidae) to Affect Dung-Generated Greenhouse Gases in the Pasture.

Research suggests dung beetles can churn, aerate, and desiccate dung in ways that influence the dung and soil microbes producing greenhouse gases (GHGs). We examined the impacts of the tunneling beetle, Onthophagus taurus (Schreber), and the dwelling beetle, Labarrus pseudolividus (Balthasar), on the carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emitted from pasture-laid bovine dung as well as their sum-total (CO2 + CH4 + N2O) effect on global warming, or their carbon dioxide equivalent (CO2e). Despite dung beetles potential effects on CH4 and N2O, the existing literature shows no ultimate CO2e reductions. We hypothesized that more dung beetles would degrade pats faster and reduce CO2e, and so we increased the average dung beetle biomass per dung volume 6.22× above previously published records, and visually documented any dung damage. However, the time effects were 2–5× greater for any GHG and CO2e (E = 0.27–0.77) than dung beetle effects alone (E = 0.09–0.24). This suggests that dung beetle communities cannot adequately reduce GHGs unless they can accelerate dung decomposition faster than time alone.

Canopy cover is a key factor to preserve the ecological functions of dung beetles in the southern Atlantic Forest

In general, livestock activities affect the diversity and ecological functions of dung beetles. However, some practices associated with tree retention could reduce this problem while maintaining productivity. The objective of this study was to explore the influence of canopy cover on dung beetle biomass, their burial activity and changes in soil conditions associated with this activity, in the southern Atlantic Forest of Argentina. Four habitat types were compared: (i) native forest, (ii) silvopastoral systems with native trees, (iii) silvopastoral systems with exotic trees (Pinus taeda), and (iv) open pastures. Canopy cover, and microclimatic and soil conditions were also evaluated in each habitat type. The native forest and silvopastoral systems (both native and exotic) showed lower temperatures, higher relative humidity, higher electrical conductivity, and higher nitrate (N-NO3) and sand contents than open pastures, which showed opposite microclimatic conditions and higher clay contents. In addition, field experiments using acrylic plastic beads and cow dung were performed to evaluate the burial activity of dung beetles, and its influence on soil properties. Soil samples were collected after 30 days to compare the soil conditions among habitat types. Total burial (>95%) and depth (5–6 cm) of acrylic plastic beads were higher in habitat types with native trees than in livestock systems with exotic trees and open pastures; moreover, dung beetle total biomass was strongly and linearly related to burial activity among habitat types. We observed no direct influence of burial activity on soil properties. Our results support the idea that livestock systems with native trees improve the environmental parameters, biomass and ecological functions of dung beetles compared with silvopastoral systems with exotic trees and open pastures.

Habitat continuity matters: Ancient woodlands tend to have higher biomass and catching rate of dung beetles, mainly driven by one large species

Ancient woodlands differ from recent woodlands by numerous abiotic and biotic factors, including soil properties. Several animal species are more abundant in ancient than in recent woodlands, but this has been only rarely tested for saprophagous taxa and not at all for dung beetles, which are common in temperate woodlands. Beside habitat continuity, tree age can have also an effect on woodland inhabiting animals, especially on saprophagous taxa. To analyze the effects of both habitat continuity and tree age we studied dung beetles in a continuous north-west German woodland with baited pitfall traps on basis of a factorial design. We compared species diversity (Shannon-Wiener-Index and Pielou's Evenness), catching rates, biomass and community composition of dung beetles. With only 18 recorded species from 20 study plots, dung beetle communities were species-poor and dominated by one large tunnelling species. The main result is that catching rate and biomass of dung beetles were higher in ancient woodlands, which was due to the particularly high catching rate of the most dominant tunnelling species and one dweller species. Tree age alone had a minor impact, but affects significantly one rare species. Diverging habitat quality of ancient and recent woodlands likely explains differences in the communities of dung beetles in woodlands of different habitat continuity. Old trees in recent woodlands could not compensate for habitat continuity of ancient woodlands.

Stronger dung removal in forests compared with grassland is driven by trait composition and biomass of dung beetles

1. Ecosystem processes depend on the biomass of the involved organisms, but their functional diversity may play an additional role. In particular, the exclusion of key functional groups through habitat disturbance may lead to the breakdown of ecosystem functions. Dung removal is an important process contributing to nutrient cycling and thus productivity in grazed ecosystems.2. This study investigated the role of different functional groups of dung beetles in dung removal in different habitats within a wood‐pasture in two different seasons. An experimental setting with 12 blocks and 108 dung pads was used to investigate short‐term dung removal over 1 week of exposure.3. Dung removal was most strongly affected by habitat type, with almost 40% lower levels in grassland than in adjacent forest and forest gaps. Of all assemblage characteristics, total biomass of tunneller species was the strongest predictor of dung removal, whereas functional diversity showed no significant effect. In accordance with the dung removal pattern at habitat type level, densities of large tunnellers were suppressed in grassland compared with forest.4. It is concluded that dung removal is habitat‐specific and large tunnellers play a disproportionate role in this important ecosystem function in temperate forests.

Linking dung beetle diversity and its ecological function in a gradient of livestock intensification management in the Neotropical region

In the coming decades, the rapid expansion of livestock production in highly biodiverse regions is likely to increase deforestation, threatening biodiversity and disrupting key ecological functions. However, the relationship between biodiversity and ecosystem function in tropical livestock-dominated landscapes is still poorly understood and empirically under-explored. We evaluated how livestock intensification affects different attributes of the dung beetle community (species richness, number of individuals, and biomass) and their impact to dung removal. The study was done in twenty 1-km2 sites in the Yucatan Peninsula, Mexico. These sites were located within a heterogeneous region representing five different land management types ranging from tropical dry forest to high-yield cattle ranches, including traditional and silvopastoral systems. The most plausible diversity-function relationship was based on biomass, while species richness and number of individuals were less supported and had similarly shaped diversity-function relationships. We found that intensification of livestock management drastically reduced dung beetle biomass which affected the rate of dung removal. Our results also show that the loss of larger-sized dung beetle species following forest loss has an effect on the rate of dung removal. Nonetheless, the remarkable increase in abundance of small-sized species seems to compensate for potential losses of function in low-yield cattle farms, as in the case of traditional and silvopastoral systems. Although low- and medium-yield livestock landscapes harbour high species richness and similar dung removal rate versus forested sites, other community attributes such as biomass provide additional information in understanding the effects of management practices in the livestock-dominated landscape.

Dung burial by roller dung beetles (Coleoptera: Scarabaeinae): An individual and specific-level study

AbstractDung beetles (Coleoptera: Scarabaeinae) mediate many ecological functions that are important to maintain the ecosystem functioning of terrestrial environments. Although a large amount of literature explores the dung beetle-mediated ecological processes, little is known about the individual contribution from distinct species. Here, we aimed to examine the intra and interspecific variations in dung burial rates performed by two roller dung beetle species (Canthon smaragdulusFabricius, 1781 andCanthon sulcatusCastelnau, 1840). Furthermore, we evaluated the relationship between dung beetle biomass and dung burial rates. We set up a laboratorial experiment with three treatments (two males, two females, and a couple) and 10 replicates per treatment for each dung beetle species, and dung burial rates were measured after exposing 100 g of mixed pig and human excrement for 48 hours. Our results demonstrate that dung burial rates of males, females, and couples within each species do not differ. However,C. smaragdulusindividuals performed a larger dung burial thanC. sulcatusindividuals did. In addition, we found no effect of individual biomass on the amount of dung burial on intra and interspecific levels. These findings highlight the need for further research considering that distinct species, even from the same genus, may perform different rates of ecological processes, as well as about the importance for considering the beetle biomass when measuring their ecological functions. We call for studies to fill in the knowledge gap about the individual species’ contribution to the maintenance of different dung beetle-mediated ecological processes.

Large herbivores affect forest ecosystem functions by altering the structure of dung beetle communities

Dramatic increases in populations of large mammalian herbivores have become a major ecological issue, particularly in the northern hemisphere, due to their substantial impacts on both animal and plant communities through processes such as grazing, browsing, and trampling. However, little is known about the consequences of these population explosions on ecosystem functions. Here, we experimentally investigated how the population density of sika deer (Cervus nippon) in temperate deciduous forest areas in Japan affected the decomposition of mammal dung by dung beetles, which is a key process in forest ecosystems. We measured a range of environmental variables (e.g., vegetation cover, soil hardness) and the dung decomposition rate, measured as the amount of deer dung decomposed during one week, and sampled dung beetles at 16 study sites with three different deer densities (high/intermediate/low). We then used structural equation modeling to investigate the relationships between deer density, environmental variables, the biomass of dung beetles (classified into small or large species), and the dung decomposition rate. We found that the biomass of small species increased with increasing deer density, whereas that of large species was not related to deer density. Furthermore, the dung decomposition rate was positively related to the biomass of small species but unrelated to that of large species. Overall, our results showed that an increase in deer density affects the decomposition rate of mammal dung by changing the structure of dung beetle communities (i.e., increasing the number of small dung beetles). Such an understanding of how increases in large herbivore populations affect ecosystem functions is important for accurately evaluating the ecological consequences of their overabundance and ultimately managing their populations appropriately.

Decline of Ecological Functions Performed by Dung Beetles in Areas of Atlantic Forest and Contribution of Rollers and Tunnellers in Organic Matter Removal.

The feeding behavior of the Scarabaeinae subfamily has positive implications on ecosystem functioning. We characterize the necrophagous and coprophagous dung beetle assemblages, and we quantify the removal of swine carrion and domestic dog dung in two areas with different degrees of environmental disturbance in an Atlantic Forest remnant located in Florianopolis, SC, Brazil. The experiment was setup at eight sampling points in each area, by installing one control and two collection and removal assessment arenas for collecting necrophagous dung beetles while simultaneously evaluating the removal of carrion (50 g of rotting pork for 48 h). We used the same sample design with 50 g of domestic dog dung for evaluating the coprophagous dung beetle assemblage and dung removal. Our results indicated that necrophagous dung beetles were more sensitive to environmental disturbance owing to a lower richness and changes in species dominance, which resulted in a lower removal in the areas with greater disturbance and lower environmental quality (39.6% carrion removal) in relation to less disturbed areas (75.1% carrion removal). The dung beetle assemblages were similar in structure and removal rates between areas (80% of dung was removed). In assessing the influence of richness, abundance, and biomass of dung beetles on resource removal both for the whole assemblage and for each separate functional guild, only the abundance and biomass of rollers contributed significantly to dung removal. These results highlight the implications of environmental disturbances on the functions of dung beetles, which respond differently according to the resource they use.

Land use affects dung beetle communities and their ecosystem service in forests and grasslands

Abstract Dung beetles (Scarabaeidae) are common detritivores, and especially the tunnelling genera Geotrupes, Anoplotrupes and Onthophagus enhance the soil quality and support nutrient cycles by rapid burial of mammalian dung. These functionally important beetles are faced with a wide range of anthropogenic disturbances and changes in environmental conditions due to land use. We thus conducted quantitative surveys of the abundance (converted to total biomass) of dung beetles and their dung removal rates (g per two days) in 150 forest and 150 grassland sites with varying land-use intensity, located in north-east, central and south-west Germany. We used dung from livestock (cow, sheep, horse) and game animals (wild boar, red deer and fox) to provide a characteristic spectrum of dung resources on each site. Most dung beetle species showed habitat preferences: Anoplotrupes, Typhaeus and several Aphodius species almost exclusively occurred in forests, while most Onthophagus individuals were found in grasslands. In total we collected 18780 individuals from 33 species. The average dung beetle biomass was 36 times higher in forests than in grasslands, and their effective dung removal rate was 3 times increased. The beetles’ total biomass was strongly correlated to their removal rates. In forests, the amount of wood harvesting significantly reduced dung removal rates by 20%, and mowing frequency (−7%) and fertilisation (−4%) had a significant negative effect in grasslands. Dung removal by beetles increased with grazing intensity (+6%), however, and was higher in non-native coniferous forests (+22%). Overall, our study demonstrates negative effects of habitat conversion from forest to grassland, and negative effects of land-use intensity within forests and grasslands on dung beetle activities.

The value of trophic interactions for ecosystem function: dung beetle communities influence seed burial and seedling recruitment in tropical forests.

Anthropogenic activities are causing species extinctions, raising concerns about the consequences of changing biological communities for ecosystem functioning. To address this, we investigated how dung beetle communities influence seed burial and seedling recruitment in the Brazilian Amazon. First, we conducted a burial and retrieval experiment using seed mimics. We found that dung beetle biomass had a stronger positive effect on the burial of large than small beads, suggesting that anthropogenic reductions in large-bodied beetles will have the greatest effect on the secondary dispersal of large-seeded plant species. Second, we established mesocosm experiments in which dung beetle communities buried Myrciaria dubia seeds to examine plant emergence and survival. Contrary to expectations, we found that beetle diversity and biomass negatively influenced seedling emergence, but positively affected the survival of seedlings that emerged. Finally, we conducted germination trials to establish the optimum burial depth of experimental seeds, revealing a negative relationship between burial depth and seedling emergence success. Our results provide novel evidence that seed burial by dung beetles may be detrimental for the emergence of some seed species. However, we also detected positive impacts of beetle activity on seedling recruitment, which are probably because of their influence on soil properties. Overall, this study provides new evidence that anthropogenic impacts on dung beetle communities could influence the structure of tropical forests; in particular, their capacity to regenerate and continue to provide valuable functions and services.

A dirty job: manure removal by dung beetles in both a cattle ranch and laboratory setting

AbstractDung beetles (Coleoptera: Scarabaeidae, Scarabaeinae) play a crucial role in natural ecosystems and grazing areas because they are actively involved in dung removal and other ecosystem processes such as nutrient cycling. We assess the manure removal process performed by dung beetles on a cattle ranch with temperate forest remnants in the Mexican Transition Zone of central Mexico. Despite having similar species richness, the amount of dung removed by the beetle community on pastures was higher than in forest remnants, but there were no significant differences between dung types (cow and sheep). Using field mesocosms, we found differences in the amount of dung removed by eight of the most abundant species in the study area. As in the field, in the laboratory large species (Deltochilum scabriusculum Bates, Dichotomius colonicus Say, and Phanaeus adonis Harold) removed larger amounts of dung during the first days of the process. We found positive and significant relationships between species biomass and the amount of dung removed, both in mesocosms and in the laboratory. Our results suggest that in spite of habitat type, dung beetle biomass is one of the main factors driving the process of dung removal. A better understanding of the dynamics of ecosystem processes where dung beetles participate will improve the design of management plans to promote sustainability and ecosystems integrity in livestock areas.

Forest loss and matrix composition are the major drivers shaping dung beetle assemblages in a fragmented rainforest

Identifying the drivers shaping biological assemblages in fragmented tropical landscapes is critical for designing effective conservation strategies. It is still unclear, however, whether tropical biodiversity is more strongly affected by forest loss, by its spatial configuration or by matrix composition across different spatial scales. Assessing the relative influence of forest patch and landscape attributes on dung beetle assemblages in the fragmented Lacandona rainforest, Mexico. Using a multimodel inference approach we tested the relative impact of forest patch size and landscape forest cover (measures of forest amount at the patch and landscape scales, respectively), patch shape and isolation (forest configuration indices at the patch scale), forest fragmentation (forest configuration index at the landscape scale), and matrix composition on the diversity, abundance and biomass of dung beetles. Patch size, landscape forest cover and matrix composition were the best predictors of dung beetle assemblages. Species richness, beetle abundance, and biomass decreased in smaller patches surrounded by a lower percentage of forest cover, and in landscapes dominated by open-area matrices. Community evenness also increased under these conditions due to the loss of rare species. Forest loss at the patch and landscape levels and matrix composition show a larger impact on dung beetles than forest spatial configuration. To preserve dung beetle assemblages, and their key functional roles in the ecosystem, conservation initiatives should prioritize a reduction in deforestation and an increase in the heterogeneity of the matrix surrounding forest remnants.

Species-specific effects of dung beetle abundance on dung removal and leaf litter decomposition

In grazed ecosystems, coprophagous beetles are known to play an important role in nutrient cycling, but interactions between species identity and dung beetle abundance on soil processes remain unclear. We conducted an outdoor mesocosm experiment to investigate the effects of three dung beetle species at four levels of abundance on dung incorporation into the soil. In addition we assessed indirect effects of dung beetle activity on leaf litter decomposition by microorganisms in soil. Both dung removal and leaf litter mass loss were positively correlated with initial dung beetle biomass and beetle abundance across species. However, the magnitude of beetle-induced increases in litter mass loss was very small compared to the magnitude of beetle effects on dung removal. Beetle effects on dung removal and litter decomposition also showed significant abundance × species interactions, with strongest responses observed for Colobopterus erraticus Linnaeus. Our findings highlight the importance of interactive effects between species identity and abundance on dung removal and provide the first demonstration of indirect dung beetle effects on leaf litter decomposition in soil.