The influence of landscape structure on ants and dung beetles diversity in a Mediterranean savanna—Forest ecosystem

Ants and dung beetles are focal indicators of change in several ecological processes and successional vegetation stages in Mediterranean landscapes. Despite relatively good knowledge of local species distributions, there are few data on their distributions at different scales. In the present study, the influence of multiscale landscape structure was examined using both ants and dung beetles to identify species that can serve as indicators and detectors of changes in vegetation structure. Multiscale analysis is necessary to explore the different roles of indicator and detector species for use as tools in studies focused on monitoring ecological changes. The study area was the Cabañeros National Park, in the center of the Iberian Peninsula. This site was selected because it is a good setting to evaluate the effects of typical vegetation mosaics on Mediterranean species at different scales. In this study, dung beetles and ants were trapped for one year. A multiscale analysis was designed using three different vegetation habitats (forest, scrubland and grassland) and landscape matrices (woodland, scrubland and grassland). Among dung beetles, 23 indicator species (IndVal values higher than 70%) were found at different scales of analysis. In addition, 20 dung beetle species were characterized as detector species (IndVal values between 45 and 70%) for the three different levels analyzed. Similar to the dung beetles, the ants had different species assemblages at various habitats and landscape levels; however, no indicator ant species were found in this study. All species with significant IndVal values (n = 8) were identified as detector species. Thus, ant and dung beetle assemblages were influenced in different ways by vegetation structure. Both groups showed strong individual species responses to different Mediterranean landscape conditions and vegetation types. Further, both insect groups showed a great number of detector species, which can be useful in ecosystem management because they have varying degrees of preference and sensitivity for different ecological states (such as successional vegetation stages). The diverse indicator and detector species identified in this work could be useful tools for the detection of landscape structure changes at both levels habitat patches and landscape matrix. However, a generalisation of the results at landscape scale should be taken with precaution, but they encourage to study more regions and similar landscapes. The use of more than one indicator group in the analysis confirms the importance of selecting groups with different sensitivities at varying spatial scales as well as different ecosystem functions. This strategy allows the establishment of a clear baseline with which to analyze future direct and indirect impacts of management in Mediterranean protected areas.     

Dung beetles in continuous forest, forest fragments and in an agricultural mosaic habitat island at Los Tuxtlas, Mexico

With the aim of determining what kind of landscape mosaics might sustainmaximum diversity and minimum species loss, dung beetles were sampled withbaited pitfall traps to compare species richness and species composition in atract of continuous forest, forest fragments and a habitat island consisting ofa mosaic of forest and arboreal crops in Los Tuxtlas, southern Mexico. Wecaptured 7332 dung beetles representing 33 species. Similar numbers of specieswere captured in the three habitats. However, 56% of individuals were capturedin the continuous forest, 29% in the mosaic habitat and 15% in the forestfragments. Eight species (Canthon femoralis,Copris laeviceps, Canthidium centrale,Onthophagus batesi, Deltochilumpseudoparile, O. rhinolophus, Canthonviridis vazquezae and Dichotomius satanus) accounted for 90% of thecaptures, but their relative dominance varied among habitats. A clear trend wasevident in the number of dung beetles captured in the dung processing guilds(rollers/tunnelers) as well as in the diurnal and nocturnal guilds, withcaptures decreasing from the continuous forest to the mosaic habitat to theforest fragments. A similar trend was detected in detection rates for medium andsmall size dung producing mammals. Species richness of forest fragments andmosaic habitat did not differ from that found in the continuous forest, butthese habitats differ significantly in species richness from isolated shaded andunshaded plantations, linear strips of vegetation, the forest–pasture edge andpastures according to rarefaction analysis. The co-occurrence of the continuousforest, the mosaic habitat and the cluster of forest fragments in closeproximity seems to be preserving a diverse assemblage of dung beetle species inthe local landscape.     

Monitoring the ecosystem service provided by dung beetles offers benefits over commonly used biodiversity metrics and a traditional trapping method

Surveying terrestrial invertebrates often requires lethal techniques that can also kill non-target vertebrates. Removing the desirable components of biodiversity is at odds with the philosophy of ecological restoration and biodiversity conservation more generally. Moreover, commonly used metrics generated by such survey approaches (e.g. abundance and species richness) are only indirectly related to the ecosystem services (e.g. pollination) that are often of primary interest. We examined the relationship between rates of dung removal (a direct measure of an ecosystem service) and dung beetle abundance and species richness in a temperate region of New South Wales, Australia, and examined if dung removal in revegetated riparian areas of different ages were trending monotonically toward rates in areas with mature native vegetation. Pellets of pig manure and conventional traps were left at study sites for 48 h to examine the relationships between rates of dung removal and dung beetle abundance and richness. Regressions of abundance and richness with average percent dung removal were positive and significant, demonstrating the potential of the method as a non-lethal proxy. While the dung removal method cannot determine the species responsible, percentage dung removal was more time-efficient, costing 4 min per sample, while abundance and richness cost 13 and 17 min, respectively. Despite variability among replicates of the same habitat type, the trajectory across the restoration gradient showed an increase from sites recently revegetated toward those with mature woody vegetation. We interpreted these results as a positive response of dung beetle activity and an indication of recovery of this ecosystem service. We argue that responses that can be collected efficiently such as dung removal should be used if restorationists have limited resources for data collection and analysis; non-specialists are involved; knowledge of ecosystem function is required, and animal ethics constrain options.     

Responses of Etiella zinckenella to habitat fragmentation of Caraganas in desert steppe in Ningxia, China

Habitat fragmentation is a common cause for which species becomes threatened or endangered. Existence of viable habitat is critical to the survival of any species, so habitat fragmentation is the main reason for the changes in distribution and abundance of organisms, and is usually considered to have negative effect on the abundance, species richness and population of organisms in a specific landscape. But this effect may also depend on whether some species could use one or more types of habitat in a specific landscape. Because of its well resistance to stress, Caragana is one of predominant shrub in desert region for forest planting and desert preventing, which plays a critical role in desert control and ecosystem stabilization. Baijitan National Nature Reserve, located in Lingwu County, Ningxia Hui Autonomous Region, China, is typical of desert nature reserve in which the Caragana spp., Oxytropis aciphylla and other desert plants are protected. The Caragana woodlands in this region show a pattern of dots, patches and strips separated by natural and cultivated forest, thereby leading to a typical fragmented landscape. Etiella zinckenella (Lepidoptera, Pyralidae) is one of seed pests of Caragana. In order to illuminate the responses of E. zinckenella to the habitat fragmentation of Caraganas woodlands, the present study focused on the effects of habitat area, habitat fragmentation, as well as matrix composition on the population density and damage ratio of E. zinckenella in desert steppe. From May 2008 to June 2009, by using parallel jump sampling method, 13 Caragana woodland patches representing four landscapes from Baijitan National Nature Reserve were investigated and totally 15,117 pods were inspected. Then, the landscape fragmentation indices, population density and damage ratio of E. zinckenella in Caragana woodlands were calculated. The statistic analysis of the data indicated that the four landscapes have a significant difference in the population density and damage ratio of E. zinckenella; and in the same landscape, the neighbor patches also have a significant difference in the damage ratios of E. zinckenella. E. zinckenella seems to prefer some species of Caragana, for instance, the damage ratio of E. zinckenella to Caragana microphylla is found the highest, followed by the damage ratio to Caragana davazamcidamage, while the damage ratio to Caragana korshinskii is found the lowest. The coverage of Caragana is found positively related to the damage ratio of E. zinckenella with hinge damage ratio in high coverage of Caragana forest. The regression analysis shows that the latitude (R_s = 0.5724), longitude (R_s = 0.5577), altitude (R_s = 0.4614) and patch area (R = 0.3012) were not significantly associated with population density and damage ratio of E. zinckenella. However, the population density and damage ratio of E. zinckenella decreased with the increasing in patch area. The landscape patch fragmentation index (R = 0.91129) and the patch density index (R = 0.89864) show a positive correlation with damage ratio. The fragmentation shape index (R = ?0.89675) and inside habitat area fragmentation index (R = ?0.77646) show a negative correlation with the damage ratio. As a result, the population of E. zinckenella was suppressed by the landscape fragmentation, but the patch isolation and complementary resources in the landscape matrix may also have a positive impact on the population density of E. zinckenella.     

Determinants of smooth-coated otter occupancy in a rapidly urbanizing coastal landscape in Southeast Asia

Urbanization often has negative impacts on wildlife, nevertheless many species can persist in heavily modified habitats. Understanding factors that promote species persistence in urbanizing landscapes is therefore important for maintaining biodiversity in changing landscapes and may inform more biodiversity-friendly development. We investigated effects of landscape-scale variables on habitat occupancy of Smooth-coated otter (Lutrogale perspicillata) in the Inner Gulf of Thailand. In this internationally important wetland complex, 86% of natural habitats have been altered and are now highly urbanized. We conducted track and sign surveys in 60, 25 km² grid cells encompassing 1,474 km². Within each cell, we quantified the landscape cover types including urban areas, natural habitat (predominately thin ribbons of mangrove along waterways), agriculture, aquaculture, and potential prey availability using a GIS and field surveys. We used occupancy models to identify habitat variables that affected probability of detection and occupancy. Estimated otter occupancy, based on the top model, was 0.33 ± 0.07 (95% CI 0.18–0.48) and detection probability was 0.50 ± 0.05 (95% CI 0.41–0.60). Otter occupancy was positively associated with the proportion of natural habitat and the cover of traditional aquaculture ponds, but negatively associated with agriculture and urban cover. The remaining natural patches appear to act as critical refuges for otter, allowing them to persist in an otherwise heavily transformed landscape. Because aquaculture ponds are likely important prey sources for otters, it may lead to conflict with aquaculture farmers. Further studies of feeding and movement patterns in cooperation with aquaculture farmers would be beneficial for developing detailed management plans for the species in this human dominated landscape.     

Strong influence of long-distance edge effect on herb-layer vegetation in forest fragments in an agricultural landscape

In agricultural landscapes in central Europe, species richness of the herbaceous plant community may be compromised by processes associated with forest fragmentation, habitat loss, and management practices. We examined variability in species richness and composition of the herbaceous layer in 229 plots located in 23 forest fragments (0.1 to 255 ha), in a representative upland agricultural landscape in central Bohemia, in relation to the most important site environmental factors, edge effects, and site history. The influence of environmental factors on the composition of vegetation in the herb layer was evaluated using generalized additive models, which enabled us to analyze highly non-linear and non-monotonic relationships. Total species richness and number of red-listed and ancient forest species were significantly influenced by type of forest vegetation, light quality, soil pH, slope aspect, and distance from the forest edge. Implications of the significant explanatory variables corresponded well to previous findings, with the exception of distance from the forest edge, for which we found a positive relationship with species richness for distances up to 200 m toward the forest interior. Plant species with low colonization ability occupied plots with increasing frequency from edge to forest interior, while fast-colonizing species showed the opposite trend. Apart from the edge effect, forest continuity should be considered for its important contribution to the richness of ancient forest and red-listed species, whereas the effect of forest fragment size appeared to be generally weak. These results do not negate the importance of large forest fragments for the maintenance of herb layer species richness, but specifically emphasize the essential contribution of the core habitats of these forests. In summary, we showed that the negative effects of habitat fragmentation on the richness of ancient forest and red-listed species and on herb layer species in total can be largely attributed to either the edge effect itself or to aggregate effects of forest edge and forest continuity.     

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.     

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.     

Extinction thresholds and negative responses of Afrotropical ant-following birds to forest cover loss in oil palm and agroforestry landscapes

Afrotropical ant-following birds are vulnerable to forest loss and disturbance, but critical habitat thresholds regarding their abundance and species richness in human-dominated landscapes, including industrial oil palm plantations, have never been assessed. We measured forest cover through Landsat imagery and recorded species richness and relative abundance of 20 ant-following birds in 48 plots of 1-km², covering three landscapes of Southwest Cameroon: Korup National Park, smallholder agroforestry areas (with farms embedded in forest), and an industrial oil palm plantation. We evaluated differences in encounter frequency and species richness among landscapes, and the presence of critical thresholds through enhanced adaptive regression through hinges. All species were detected in Korup National Park and the agroforestry landscape, which had similar forest cover (>85%). Only nine species were found in the oil palm plantation (forest cover = 10.3 ± 3.3%). At the 1-km² scale, the number of species and bird encounters were comparable in agroforests and the protected area: mean species richness ranged from 12.2 ± 0.6 in the park and 12.2 ± 0.6 in the agroforestry matrix to 1.0 ± 0.4 in the industrial oil palm plantation; whereas encounters decreased from 34.4 ± 3.2 to 26.1 ± 2.9 and 1.3 ± 0.4, respectively. Bird encounters decreased linearly with decreasing forest cover, down to an extinction threshold identified at 24% forest cover. Species richness declined linearly by ca. one species per 7.4% forest cover lost. We identified an extinction threshold at 52% forest cover for the most sensitive species (Criniger chloronotus, Dicrurus atripennis, and Neocossyphus poensis). Our results show that substantial proportions of forests are required to sustain complete ant-following bird assemblages in Afrotropical landscapes and confirm the high sensitivity of this bird guild to deforestation after industrial oil palm development. Securing both forest biodiversity and food production in an Afrotropical production landscape may be best attained through a combination of protected areas and wildlife-friendly agroforestry.     

Effect of landscape structure on the spatial distribution of Mediterranean dung beetle diversity

Aim  Landscape structure influences the distribution of animals, altering their movements and their ability to reach habitat patches. We analysed the spatial patterns of dung beetle species diversity in three differently structured natural landscapes in a Mediterranean protected area in the centre of the Iberian Peninsula.
Location  Cabañeros National Park, Central Spain.
Methods  Diversity components within (α) and among (β) the three main vegetation types in the reserve were compared by using a hierarchical nested design. These were forests, scrublands and grasslands embedded in three different landscapes, where each was the most dominant and structurally connected habitat.
Results  Species richness of grassland habitat did not vary across landscapes, but forest habitat showed lower species richness in the grassland-dominated landscape. Scrubland was the least species-rich habitat, but here again there was no significant variation across landscapes. However, in all cases, there was a significant influence of habitat context (configuration of habitat patches within landscape matrix) on similarity of species composition. These tended to be more similar to the dominant landscape matrix where they were embedded, rather than to the same habitat type in other landscapes. Additive partitioning of diversity showed higher than expected values of β in all landscapes, which indicated a structured response. Highest values of β in the grassland-dominated landscape suggest that this was the least connected landscape for dung beetles.
Main conclusions  Our results suggest that in homogeneous conditions of climate and trophic resources, landscape structure may well be more important than habitat type as a determinant of dung beetle distribution in the Mediterranean.     

Landscape-scale crop diversity interacts with local management to determine ground beetle diversity

Crop diversification and maintenance of semi-natural habitats (grasslands and field boundaries) are suggested to enhance farmland biodiversity, but the relative importance of these factors remains poorly known. We evaluated how crop diversity and availability of semi-natural grasslands at a landscape-scale interacted with local farming management (three management types from low to high intensity: ley < winter wheat < sugar beet) in their effect on ground beetle assemblages in southern Sweden. Ground beetle diversity increased with crop diversity either independently of local management (Simpson species diversity), or only in the less intensively managed habitats (rarefied species richness). While ground beetle diversity in leys tended to increase with field boundary length, no such relationship was observed in winter wheat or sugar beet fields. In contrast, the landscape proportions of leys and semi-natural grasslands did not affect ground beetle species richness and diversity. We conclude that (a) semi-natural grasslands and leys may not function as source habitats at a landscape-scale if they comprise a low proportion of the total land-use, while (b) increasing crop diversity is correlated to ground beetle richness and diversity in agricultural landscapes dominated by arable land. The beneficial effect of landscape-scale crop diversification on farmland biodiversity may depend on the general level of agricultural intensity of a region.     

Forest Loss and the Biodiversity Threshold: An Evaluation Considering Species Habitat Requirements and the Use of Matrix Habitats

Habitat loss is the main driver of the current biodiversity crisis, a landscape-scale process that affects the survival of spatially-structured populations. Although it is well-established that species responses to habitat loss can be abrupt, the existence of a biodiversity threshold is still the cause of much controversy in the literature and would require that most species respond similarly to the loss of native vegetation. Here we test the existence of a biodiversity threshold, i.e. an abrupt decline in species richness, with habitat loss. We draw on a spatially-replicated dataset on Atlantic forest small mammals, consisting of 16 sampling sites divided between forests and matrix habitats in each of five 3600-ha landscapes (varying from 5% to 45% forest cover), and on an a priori classification of species into habitat requirement categories (forest specialists, habitat generalists and open-area specialists). Forest specialists declined abruptly below 30% of forest cover, and spillover to the matrix occurred only in more forested landscapes. Generalists responded positively to landscape heterogeneity, peaking at intermediary levels of forest cover. Open area specialists dominated the matrix and did not spillover to forests. As a result of these distinct responses, we observed a biodiversity threshold for the small mammal community below 30% forest cover, and a peak in species richness just above this threshold. Our results highlight that cross habitat spillover may be asymmetrical and contingent on landscape context, occurring mainly from forests to the matrix and only in more forested landscapes. Moreover, they indicate the potential for biodiversity thresholds in human-modified landscapes, and the importance of landscape heterogeneity to biodiversity. Since forest loss affected not only the conservation value of forest patches, but also the potential for biodiversity-mediated services in anthropogenic habitats, our work indicates the importance of proactive measures to avoid human-modified landscapes to cross this threshold.     

Post-fire dynamics of woody vegetation in seasonally flooded forests (impucas) in the Cerrado-Amazonian Forest transition zone

Fire disturbance alters the structural complexity of forests, above-ground biomass stocks and patterns of growth, recruitment and mortality that determine temporal dynamics of communities. These changes may also alter forest species composition, richness, and diversity. We compared changes in plant recruitment, mortality, and turnover time over three years between burned and unburned sites of two seasonally flooded natural forest patches in a predominantly savanna landscape (regionally called ‘impucas’) in order to determine how fire alters forest dynamics and species composition. Within each impuca, 50 permanent plots (20 m × 10 m) were established and all individuals ≥5 cm diameter at breast height (DBH) identified and measured in two censuses, the first in 2007 and the second in 2010. Unplanned fires burned 30 plots in impuca 1 and 35 in impuca 2 after the first census, which enabled thereafter the comparison between burned and unburned sites. The highest mortality (8.0 and 24.3% year⁻¹ for impuca 1 and 2) and turnover time (69 and 121.5 years) were observed in the burned sites, compared to 3.7 and 5.2% year⁻¹ (mortality), and 28.4 and 40.9 years (turnover), respectively, for the unburned sites. Although these seasonally flooded impuca forests are embedded in a fire-adapted savanna landscape, the impucas vegetation appears to be sensitive to fire, with burned areas having higher mortality and turnover than unburned areas. This indicates that these forest islands are potentially at risk if regional fire frequency increases.     

How far a protected area contributes to conserve habitat species composition and population structure of endangered African tree species (Benin,West Africa)

The Pendjari Biosphere Reserve located in the Sudanian zone of Bénin, is a protected area well managed, but mainly aimed at wild animal conservation. This study assessed its effectiveness to conserve habitat species composition and population structure of three endangered African tree species: Afzelia africana Sm., Pterocarpus erinaceus Poir. and Khaya senegalensis (Desv.) A. Juss. We randomly sampled 120 plots in the protected and surrounding unprotected habitats by inventorying plant species. For the three target species, we estimated adult and juvenile densities and recorded size classes. According to floristic composition four habitats groups were recognized in relation to human disturbance, vegetation type, and moisture. These were protected savannas, unprotected savannas, old fallows and gallery forests. The estimated adult densities of A. africana were similar between protected (14 ± 1.2 tree/ha) and unprotected savannas (17 ± 0.9 tree/ha) while for P. erinaceus the adult density was significantly higher in protected (12 ± 3.7 tree/ha) than in unprotected savannas (5 ± 1.9 tree/ha). Estimated adult density of K. senegalensis was also significantly higher in protected gallery forest (40 ± 5.8 tree/ha) than in unprotected one (29 ± 4.8 tree/ha). Juvenile densities of A. africana, K. senegalensis and P. erinaceus were higher in protected habitats than in unprotected ones but the difference was not significant. Skewness coefficient indicated that populations of investigated trees were declining in their protected habitats. However, in the case of A. africana and K. senegalensis populations seemed to be mostly threatened in the protected area. We concluded that although the studied protected area is effective to conserve some habitats species compositions, protection is not sufficient to guarantee future conservation of some threatened tree species.     

Species–area models to assess biodiversity change in multi-habitat landscapes: The importance of species habitat affinity

Species–area relationships (SARs) are a common tool to assess the impacts of habitat loss on species diversity. Species–area models that include habitat effects may better describe biodiversity patterns; also the shape of the SAR may be best described by other models than the classical power model. We compared the fit of 24 SAR models, i.e. eight basic models using three approaches: (i) single-habitat models, (ii) multi-habitat models which account for the effect of the habitat composition on total species diversity (= choros models) and (iii) multi-habitat models which also account for the differential use of habitats by different species groups (= countryside models). We use plant diversity data from a multi-habitat landscape in NW Portugal. Countryside models had the best fit both when predicting species–area patterns of species groups and of total species richness. Overall, choros models had a better fit than single-habitat models. We also tested the application of multi-habitat models to land-use change scenarios. Estimates of species richness using the choros model only depended on the number of habitats in the landscape. In contrast, for the countryside model, estimates of species richness varied continuously with the relative proportion of the different habitat types in the landscape, and projections suggest that land-use change impacts may be moderated by a species’ ability to use multiple habitats in the landscape. We argue that the countryside SAR is a better model to assess the impacts of land-use changes than the single-habitat SAR or the choros model, as species often face habitat change instead of real habitat loss, and species response to change is contingent on their differential use of habitats in the landscape.     

Does the tropical agricultural matrix bear potential for primate conservation? A baseline study from Western Uganda

As for most large mammals, conservation research on primates usually focuses on protected areas, and yet not much is known about primate communities in land-use systems in the absence of hunting. Using line transects, we estimated population densities for four primate species in a mixed agroforest landscape up to a distance of 4000 m from a forest reserve, in a region where no primate hunting takes place. We then modelled encounter rates and cluster size in relation to landscape parameters by means of bivariate analysis and Generalised Linear Models (GLMs). Black-and-white colobus (Colobus guereza) were most common, with confidence intervals for density estimates of 31.1–62.8 individuals/km². Red-tailed monkeys (Cercopithecus ascanius) and blue monkeys (Cercopithecus mitis) occurred at 15.2–37.9 ind/km² and 13.9–36.7 ind/km² respectively, and chimpanzees (Pan troglodytes) at 1.0–2.8 ind/km². Chimpanzee nest numbers and distribution appeared to be significantly constrained by transect forest coverage, forest coverage within 500 m and distance from the main forest, whereas monkey sightings were generally less restricted by landscape variables. The considerable population density of monkeys suggests that, in the absence of hunting, mixed agroforest systems may play a relevant role in primate conservation and highlight that it is useful to consider primate ecology in land sharing approaches to conservation.     

Landscape attributes shape dung beetle diversity at multiple spatial scales in agricultural drylands

Land-use change is one of the main drivers of biodiversity loss worldwide, but its negative effects can vary depending on the spatial scale analyzed. Considering the continuous expansion of agricultural demand for land, it is urgent to identify the drivers that shape biological communities in order to balance agricultural production and biodiversity conservation in human-modified landscapes. We used a patch-landscape design and a multimodel inference approach to assess the effects of landscape composition and configuration at two spatial scales (patch and landscape) on the structure of dung beetle assemblages. We performed our study in the Caatinga, the largest dry forest in South America. We sampled 3,526 dung beetles belonging to 19 species and 11 genera. At patch scale, our findings highlight the positive relationship of forest cover and landscape heterogeneity with dung beetle diversity, which are the major drivers of beetle assemblages. Edge density, in turn, is a major driver at the landscape scale and has a negative effect on beetle diversity. Our results support the hypothesis that landscapes combining natural vegetation remnants and heterogeneous agricultural landscapes are the most effective at conserving the biodiversity of dung beetles in the Caatinga landscapes. Directing efforts to better understand the dynamics of dung beetles in agricultural lands can be helpful for policymakers and scientists to design agri-environment schemes and apply conservation strategies in tropical dry forests.     

Landscape context and elevation affect pollinator communities in intensive apple orchards

Although an extensive research has been done on the contribution of wild insects to apple pollination, most of these studies did not evaluate the effect of the surrounding landscape context on local pollinator communities. Our aim was to compare communities of wild bees in 31 equally managed apple orchards located in three contrasting landscape types (either dominated by apple, forest, or grasslands) and along an elevation gradient and to test a potential interaction between landscape context and elevation. The study was carried out in 2009 in Trentino (NE Italy), one of the major apple growing areas of Europe with ～12,000 ha of commercial orchards distributed between 150 and 950 m a.s.l. We found that apple-dominated landscapes drastically reduced wild bee species richness and abundance in the orchard compared to landscapes dominated by either grassland or forest. Forest-dominated landscapes benefited local species richness more than grassland-dominated landscapes, while abundance did not differ between grassland and forest. Total species richness and abundance further declined with increasing elevation, while no interactive effect was found between temperature and landscape context. The abundance of Apis mellifera in the apple-dominated landscapes was two to four times higher than in the landscapes dominated by forest and grasslands, respectively. Measures to restore natural pollinator communities by providing suitable habitats around the orchard would not only benefit conservation of general biodiversity, but would probably also contribute to reduce the dependence of apple pollination on managed honey bees.     

Lunar phobia in bats and its ecological correlates: A meta-analysis

Animals show several behavioral strategies to reduce predation risks. Presumably, moonlight avoidance is a strategy used by some nocturnal species to reduce the risk of predation. In bats, some research indicates that foraging activity is negatively correlated with moonlight intensity, a phenomenon better known as lunar phobia. However, the currently available evidence is contradictory because some bat species reduce their activity during nights with more moonlight while the opposite occurs in other species. We quantitatively evaluated the strength and direction of the relationship between moonlight intensity and bat activity using a meta-analysis. We also looked at some ecological correlates of lunar phobia in bats. Specifically, we examined foraging habitat and latitude as potential moderators of the size of the lunar phobia effect. Our results show that, regardless of the method used to evaluate bat activity, the overall relationship between moonlight intensity and bat activity is significant and negative (r = ?0.22). Species foraging on the surface of the water (piscivores and insectivores; r = ?0.83) and forest canopy species (i.e., big frugivores; r = ?0.30) are more affected by moonlight than those with different foraging habitats (understory, subcanopy, open air). Latitude was positively correlated with lunar phobia (r = 0.023). The stronger lunar phobia for bats foraging on the water surface and in the forest canopy may suggest that the risk of predation is greater where moonlight penetrates more easily. The significant effect of latitude as a moderator of lunar phobia suggests that there is a weak geographic pattern, with this phobia slightly more common in tropical bats than in temperate species.