Functionally richer communities improve ecosystem functioning: Dung removal and secondary seed dispersal by dung beetles in the Western Palaearctic (original) (raw)
Related papers
Frontiers of Biogeography, 2018
By manipulating faeces during feeding and breeding, dung beetles (Coleoptera: Scarabaeidae) fulfil important ecosystem functions in terrestrial ecosystems throughout the world. In a pan-European multi-site experiment (MSE), we estimated the ecosystem functions of dung removal and secondary seed dispersal by differing combinations of dung beetle functional groups. Therefore, we classified dung beetles into five functional groups according to their body size and dung manipulation method: dwellers, large and small tunnelers, and large and small rollers. Furthermore, we set up a dung beetle sampling database containing all sampled dung beetles during the project. By identifying dung beetle specimens to the species level, we obtained a detailed insight into the dung beetle communities at each study location. By establishing experimental plots allowing and inhibiting specific combinations of functional groups in the local dung beetle assemblage from removing dung and seeds, we estimated the role of each group in dung removal and secondary seed dispersal during a 4-week period. We performed all experiments in grazed (semi-) natural grasslands, and used different dung types (cattle, horse, sheep, goat or red deer) to match the herbivore species grazing in close vicinity of each of the study areas. Simultaneously, we sampled dung beetle assemblages by using pitfalls baited with the same dung types as used in the experiments. This data paper documents two datasets collected in the framework of this MSE project. All the experiments took place between 2013 and 2016 at 17 study sites in 10 countries and 11 biogeographic zones. The entire dung beetle sampling dataset was published as a sampling event dataset at GBIF. The dataset includes the sampling results of all 17 study sites, which contain 1,050 sampling events and 4,362 occurrence records of 94 species. The second dataset contains the results of the dung removal and secondary seed dispersal experiments in which we used 11 experimental treatments and the five dung types mentioned above. This experimental results dataset holds all experimental results of the MSE project (11,537 records), and was published in the online data repository Zenodo.
Oecologia, 2016
Dung beetles form an insect group that fulfils important functions in terrestrial ecosystems throughout the world. These include nutrient cycling through dung removal, soil bioturbation, plant growth, secondary seed dispersal and parasite control. We conducted field experiments at two sites in the northern hemisphere temperate region in which dung removal and secondary seed dispersal were assessed. Dung beetles were classified in three functional groups, depending on their size and dung manipulation method: dwellers, large and small tunnelers. Other soil inhabiting fauna were included as a fourth functional group. Dung removal and seed dispersal by each individual functional group and combinations thereof were estimated in exclusion experiments using different dung types. Dwellers were the most diverse and abundant group, but tunnelers were dominant in terms of biomass. All dung beetle functional groups had a clear preference for fresh dung. The ecosystem services in dung removal and secondary seed dispersal provided by dung beetles were significant and differed between functional groups. Although in absolute numbers more dwellers were found, large tunnelers were disproportionally important for dung burial and seed removal. In the absence of dung beetles, other soil inhabiting fauna, such as earthworms, partly took over the dung decomposing role of dung beetles while most dung was processed when all native functional groups were present. Our results, therefore, emphasize the need to conserve functionally complete dung ecosystems in order to maintain full ecosystem functioning.
Ecological Indicators, 2019
Grazed pastures are important habitats that support high biodiversity. However, in recent decades pasture management practices have experienced drastic changes. To identify better management practices that permit the coupling of productivity and biodiversity conservation, attention must be given to the intensity of grazing management. By using a recognized bio-indicator group such as dung beetles, we analysed the impact of grazing intensity on assemblage composition in a gradient from abandoned grazing to low and moderate grazing levels. Moreover, we studied whether or not assemblage composition shifts are related to species-specific responses or to more generalized effects by categorizing dung beetles into functional groups. We found differential effects on dung beetle communities depending on their feeding and reproductive behaviour; "no-nest building" species were the functional group most affected because of their inability to relocate food. Moreover, the decreased level of herbivory in abandoned areas led to shrub and tree encroachments. We demonstrated that dung beetles from abandoned areas were sensitive to this incipient habitat change due to the presence of indicator species associated with shrub and woodland habitats. Therefore, community composition varies depending on both speciesspecific and generalized responses due to the sensitivity of "no-nest building" species. From a management standpoint, we suggest maintaining a low to moderate level of grazing intensity to conserve a well-structured functional assemblage of dung beetles.
Ecology, 2020
The relationship between biodiversity and ecosystem functioning is often assessed through trait diversity. However, the relationship between traits and functions is typically assumed but seldom tested. We analyze the relationship between dung beetle traits and three ecological functions: dung removal, dung burial, and seedling emergence. We set up a laboratory experiment using nine Scarabaeidae species (three endocoprids, four paracoprids, and two telecoprids). We placed a sexual pair of beetles in each experimental unit, together with a mixture of dung and seeds, and measured the amount of dung removed and buried, burial depth, and the number of emerged seedlings. Sixteen morphological traits related to dung removal and burial were measured in each individual. Results indicate that these traits were related to dung beetle performance in dung removal and burial. Most traits were positively related to dung removal, indicating the existence of a general trait syndrome associated with dung manipulation and digging capability. Dung exploitation strategies did not provide further explanatory power. Seedling emergence showed a negative but weak relationship with dung burial amount and depth and species identity. This implies that specific differences in dungsoil interface activity may be important in secondary seed dispersal by dung beetles.
Species‐rich dung beetle communities buffer ecosystem services in perturbed agro‐ecosystems
Journal of Applied …, 2012
1. Many studies document high levels of functional redundancy in ecosystems, suggesting that species extinctions will not be detrimental to ecosystem functions and services. However, apparently redundant taxa may prove critical for sustaining ecosystem functions and services in the context of environmental perturbations. 2. Dung beetles (Coleoptera:Scarabaeidae) provide a valuable ecosystem service in temperate agro-ecosystems by increasing rates of dung decomposition and nutrient cycling. However, there is concern that these services may be negatively affected by changes in species richness and composition due to changes in pasture management and negative effects of anthelmintics used to control livestock parasites. 3. We used a mesocosm experiment to investigate the functional importance of dung beetle species richness in a system perturbed by the anthelmintic, ivermectin. We varied dung beetle species richness within three functional groups in factorial combination with ivermectin treatment. 4. In the short term (1-4 weeks), multi-species dung beetle assemblages achieved higher decomposition rates than monocultures, but only in ivermectin-treated dung. Varying speciesspecific sensitivities to ivermectin meant that species-rich assemblages sustained ecosystem functioning in the context of this anthropogenic perturbation. 5. Over the longer term (36 weeks), there was a significant, positive effect of species richness on dung decomposition in both ivermectin-treated and untreated dung, underlining the functional importance of maintaining a species-rich dung processing community even in the absence of perturbations to the system. 6. Synthesis and applications. The interacting effects of dung beetle species richness and ivermectin highlight the importance of maintaining diverse assemblages in the face of anthropogenic perturbations and suggest that apparent functional redundancy of species in agroecosystems should be interpreted cautiously. Furthermore, different farm management practices (e.g. pesticide use and fragmentation of habitats) may have consequences for ecosystem functions and services that exceed the effects of each when considered in isolation.
Importance of habitat heterogeneity in remnant patches for conserving dung beetles
Biodiversity and Conservation, 2013
Landscape heterogeneity affects the spatial distribution of species. This makes it an important consideration for conservation planning, particularly when designing sustainable production landscapes. We determine whether conserving landscape elements within a transformed landscape is adequate for conserving dung beetle biodiversity. Dung beetles are excellent indicators for landscape biodiversity studies as they are ecologically sensitive. Here we measure dung beetle alpha-diversity, as well as beta-diversity within landscape elements and across different landscape elements. In doing so, we assess the value of landscape elements, as well as variation within landscape elements, in determining the spatial distribution of dung beetles across a production landscape. The study was conducted in the commercial timber production area of the KwaZulu-Natal Midlands, South Africa. In this system, the different landscape elements are a mosaic of natural indigenous forests, grasslands and alien pine plantation blocks. Our results show that the only response for dung beetle alpha-diversity was higher species richness in grasslands and pine blocks compared to natural forests. The highest beta-diversity for a landscape element was the grassland, for elevational category was low elevational areas and grassland type was the Midlands Mistbelt Grassland. The compositional diversity (beta-diversity between elements) was significantly different for all pairwise variations between landscape elements, the elevational categories and grassland types. Natural forests embedded in the two different grassland types had greater differences in compositional diversity than those embedded in natural (grassland) or transformed (pine blocks) matrices. This highlights the need to conserve a range of similar remnant patches of natural vegetation regionally, in addition to conserving broad landscape elements (i.e. grasslands or natural forests) as conservation targets. Furthermore, our results are encouraging for the potential benefits from the ecosystem service provided by dung beetles across the whole landscape, even in the transformed elements.
Effect of dung beetle species richness and chemical perturbation on multiple ecosystem functions
1. The relationship between biodiversity and ecosystem functioning is typically positive but saturating, suggesting widespread functional redundancy within ecological communities. However, theory predicts that apparent redundancy can be reduced or removed when systems are perturbed, or when multifunctionality (the simultaneous delivery of multiple functions) is considered. 2. Manipulative experiments were used to test whether higher levels of dung beetle species richness enhanced individual functions and multifunctionality, and whether these relationships were influenced by perturbation (in this case, non-target exposure to the veterinary anthelmintic ivermectin). The four ecosystem functions tested were dung removal, primary productivity, soil faunal feeding activity and reduction in soil bulk density. 3. For individual functions, perturbation had limited effects on functioning, with only dung removal significantly (negatively) affected. Species richness did not, on its own, explain significant variation in the delivery of individual functions. In the case of primary productivity, an interaction between richness and perturbation was found: species-rich dung beetle assemblages enhanced forage growth in the unperturbed treatment, relative to the perturbed treatment. 4. Using a composite 'multifunctionality index' it was found that species-rich dung beetle assemblages delivered marginally higher levels of multifunctionality in unper-turbed conditions; however, this benefit was lost under perturbation. Using a relatively new and robust method of assessing diversity–multifunctionality relationships across a range of thresholds, no significant effect of species richness on multifunctionality was found.
Human perturbations reduce dung beetle diversity and dung removal ecosystem function
Biotropica, 2021
Biodiversity drives ecological functioning, ultimately providing ecosystem services. Ecosystem processes are favored by greater functional diversity, particularly when groups of functionally different species interact synergistically. Many of such functions are performed by insects, among which dung beetles stand out for their important role in dung decomposition. However, anthropogenic disturbances are negatively affecting their ecological dynamics and ecosystem services. We conducted a manipulative field study to evaluate the effect of human disturbance on dung beetle diversity (abundance, species richness, and functional group richness) and dung removal rates, comparing perturbed and conserved forests in three regions of Colombia (Caribbean, Andes, and Amazon). We also assess the relationship between dung beetle diversity and dung removal rates. Dung beetle diversity was assessed using pitfall traps, and specimens were measured and assigned to functional groups according to body size and dung relocation strategy. We used exclusion control units and experimental units to assess dung degradation with and without dung beetle activity and evaluate differences in removal rates between two dung removal strategies: paracoprids and telecoprids. Dung removal rates, abundance, and functional group richness were lower in perturbed forests compared to conserved forests. Dung removal increased with abundance, species richness, and functional group richness. Moreover, dung re- moval performed by telecoprids increased with species richness of telecoprids and paracoprids. Our results evidence a negative effect of human perturbation on dung beetle richness, abundance, and dung removal rates, and also that dung beetle diversity and functional group richness enhance dung removal rates.