Habitat structure components are effective predictors of trap-nesting Hymenoptera diversity

Habitat heterogeneity can be the major factor affecting species diversity in a community and measuring bee and wasp community habitat preferences in natural systems may provide insights for biodiversity management and conservation. In the present study, we investigate the effects of habitat structure components on solitary bee and wasp species richness and abundance. The research was conducted in an urban forest remnant in southeast Brazil. Our main questions were: (1) is similarity in habitat structure mirrored by similarity in Aculeate assemblage composition? and (2) what are the vegetation features that could be used as predictors of solitary bee and wasp richness and abundance? Aculeate bees and wasps were sampled using trap nests from February to November 2004. Trap nests were placed in sampling units located in 6 ha of secondary mesophytic forest. One hundred and thirty-seven trap nests were occupied by four species of wasps and seven species of bees. Altogether, our sampling units had a mean capture rate (relative to expected richness) of 72% during all the study period. The more similar sampling units were in terms of vegetation structure, the more similar they were in solitary bee and wasp species composition. The variance of tree abundance, shrub height and the abundance of wood logs were good predictors of solitary bee and wasp species richness and abundance in the study area. We demonstrate that even in a small scale it is possible to detect significant influences of habitat features on alpha diversity and that some of them are effective as predictors of trap-nesting Hymenoptera richness and abundance.     

High Bee and Wasp Diversity in a Heterogeneous Tropical Farming System Compared to Protected Forest

It is a globally important challenge to meet increasing demands for resources and, at the same time, protect biodiversity and ecosystem services. Farming is usually regarded as a major threat to biodiversity due to its expansion into natural areas. We compared biodiversity of bees and wasps between heterogeneous small-scale farming areas and protected forest in northern coastal Belize, Central America. Malaise traps operated for three months during the transition from wet to dry season. Farming areas consisted of a mosaic of mixed crop types, open habitat, secondary forest, and agroforestry. Mean species richness per site (alpha diversity), as well as spatial and temporal community variation (beta diversity) of bees and wasps were equal or higher in farming areas compared to protected forest. The higher species richness and community variation in farmland was due to additional species that did not occur in the forest, whereas most species trapped in forest were also found in farming areas. The overall regional species richness (gamma diversity) increased by 70% with the inclusion of farming areas. Our results suggest that small-scale farming systems adjacent to protected forest may not only conserve, but even favour, biodiversity of some taxonomic groups. We can, however, not exclude possible declines of bee and wasp diversity in more intensified farmland or in landscapes completely covered by heterogeneous farming systems.     

Spatial scale of observation affects α, β and γ diversity of cavity-nesting bees and wasps across a tropical land-use gradient

Aim Anthropogenic changes in land use may have major consequences for global biodiversity. However, species diversity is determined by a suite of factors that may affect species differently at different spatial scales. We tested the combined effects of land use and spatial scale on α, β and γ diversity in the tropics using experimental communities of cavity‐nesting bees and waSPS (Hymenoptera: Aculeata). We aimed to determine whether: (1) land‐use intensity negatively affects species richness of cavity‐nesting Hymenoptera, (2) β diversity, both within and between plots, is higher in more natural systems, (3) species richness of flowering herbs correlates positively with species richness of Hymenoptera within and across habitats, (4) richness of cavity‐nesting Hymenoptera in highly modified habitats declines with increasing distance from natural or semi‐natural habitats, (5) the effects of land use, herb diversity and forest distance on Hymenoptera α and β diversity vary at different spatial scales, and (6) bees and waSPS respond to land use in a similar way. Location Manabi, south‐west Ecuador. Methods We examined diversity (species richness) within 48 plots of five habitat types that comprised a gradient of decreasing agricultural intensity from rice and pasture to coffee agroforests, unmanaged abandoned agroforests and forest fragments, using standardized nesting resources for reproducing communities of cavity‐nesting bees and waSPS. Results (1) Land use significantly affected α diversity of trap‐nesting bees and waSPS at the subplot (per trap) scale, but not subplot β diversity or plot‐scale species richness (γ diversity). (2) Beta diversity was surprisingly higher between plots within a land‐use type than between land‐use types. (3) Species richness of bees and waSPS increased with diversity of flowering herbs at the subplot (trap) scale only. (4) Forest distance correlated positively with bee species richness at the plot scale only. (5) Land use, herb diversity and forest distance each showed significant correlations with bee and wasp diversity at only one spatial scale. (6) Despite differences in life history, bees and waSPS responded to land‐use intensity in a similar way. Main conclusions The effects of land use on species richness were highly dependent on spatial scale. Subplot‐scale analyses showed that rice and pasture contained the highest species diversity, whereas plot‐scale analyses showed no significant difference in the diversity of different land‐use types. We emphasize caution in the estimation of biodiversity at only one spatial scale, and highlight the surprisingly large contribution of managed land to the regional biodiversity of these species.     

Restore it,and they will come: trap-nesting bee and wasp communities (Hymenoptera: Aculeata) are recovered by restoration of riparian forests

Riparian forests have been greatly affected by anthropogenic actions with formerly continuous riparian forests being slowly converted into small and isolated patches. Riparian forests are extremely important habitats for many groups of insects, including bees and wasps, because they are sources of shelter and food for them and their offspring. There is a growing body of evidence of success in the restoration of riparian forest plant communities; however, little research has been done on the associated invertebrate communities. We test whether restoring plant communities is sufficient for restoring the taxonomic composition of trap-nesting bees and wasps and which functional traits are favored in different sites. We predict that species richness, abundance, and community composition of trap-nesting bees and wasps of riparian sites undergoing restoration will converge on the “target” of a reference site with increasing time, since restoration increases habitat complexity. We also predict that the width of restored patches will also influence the species richness, abundance and community composition of trap-nesting bees and wasps. Bee richness and abundance, and wasp richness, were strongly related to fragment width, but not to age since restoration. Our results indicate that although restored sites are relatively small and scattered in a fragmented landscape, they provide suitable habitat for re-colonization by community assemblages of trap-nesting bees and wasps and the traits selected captured the responses to the habitat restoration. Hence, restored riparian areas can be considered important habitats for invertebrates, thus contributing to an increase in local biodiversity and, possibly, the restoration of some of the ecosystem services they originally provided.     

Contrasting responses of hoverflies and wild bees to habitat structure and land use change in a tropical landscape (southern Yunnan,SW China)

Abstract The response of insects to monoculture plantations has mainly proceeded at the expense of natural forest areas, and is an outstanding and important issue in ecology and conservation biology, with pollination services declined around the world. In this study, species richness and distribution of hoverfly and wild bee communities were investigated in a changing tropical landscape in southern Yunnan, south‐west China by Malaise traps periodically from 2008 to 2009. Species were recorded from the traditional land use types (natural forest, grassland, shrubland and rice field fallows), and from recently established rubber plantations of different ages. Hoverflies (total 53 species) were most common in young successional stages of vegetation, including rice field fallow and shrubland. Species richness was highest in rice field fallows and lowest in forests and showed a highly significant relationship with the number of forb species and ground vegetation cover. In contrast, the highest richness of wild bees (total 44 species) was recorded from the natural forest sites, which showed a discrete bee community composition compared to the remaining habitat types. There was no significant relationship between the bee species richness and the environmental variables, including the numbers of different plant life forms, coverage of canopy and ground vegetation, successional age of vegetation and land use type. At the landscape scale, open land use systems, including young rubber plantations, are assumed to increase the species richness of hoverflies; however, this might decrease wild bee diversity. The present land use change by rubber cultivation can be expected to have negative impacts on the native wild bee communities.     

Bird diversity and endemism along a land‐use gradient in Madagascar: The conservation value of vanilla agroforests

Land‐use change is the most important driver of biodiversity loss worldwide and particularly so in the tropics, where natural habitats are transformed into large‐scale monocultures or heterogeneous landscape mosaics of largely unknown conservation value. Using birds as an indicator taxon, we evaluated the conservation value of a landscape mosaic in northeastern Madagascar, a biodiversity hotspot and the center of global vanilla production. We assessed bird species richness and composition by conducting point counts across seven prevalent land‐use types (forest‐ and fallow‐derived vanilla agroforests, woody and herbaceous fallow that are part of a shifting cultivation system, rice paddy, forest fragment and contiguous old‐growth forest). We find that old‐growth forest had the highest species richness, driven by a high share of endemics. Species richness and community composition in forest‐derived vanilla agroforest were similar to forest fragment, whereas fallow‐derived vanilla agroforest was most comparable to woody fallow. The open land‐use types herbaceous fallow and rice paddy had fewest species. Across forest fragments, vanilla agroforests, and woody fallows, endemic bird species richness was positively correlated to landscape‐scale forest cover. We conclude that both fallow‐ and forest‐derived vanilla agroforests play an important but contrasting role for bird conservation: Fallow‐derived agroforests are less valuable but take fallow land out of the shifting cultivation cycle, possibly preventing further degradation. Conversely, forest‐derived agroforests contribute to forest degradation but may avoid total loss of tree cover from forest fragments. Considering the land‐use history of agroforests may thus be a promising avenue for future research beyond the case of vanilla. Abstract in Malagasay is available with online material     

An overview of proximate factors affecting the nesting behavior of solitary wasps and bees (Hymenoptera: Aculeata) in preexisting cavities in wood

Guilds of Aculeate solitary wasps and bees that nest in preexisting cavities in wood are important components of terrestrial ecosystems because they engage in several ecological interactions (e.g. predation and pollination) with other species of plants and animals. Spatial and temporal variations in richness and abundance of solitary wasps and bees can be related to changes in environmental structure and in the diversity of other groups of organisms. The nesting period of these Aculeata is their most critical life cycle stage. Females of solitary wasp and bee species invest relatively more time constructing and provisioning their nests than do females of social species. Differently from species that nest in the soil or construct exposed nests, the main factors affecting the reproductive success of solitary species nesting in preexisting wood holes are still unknown. Our objective is to provide an overview of the role of proximate causes of nesting failure or success among solitary wasps and bees (Aculeata), for designing effective conservation and management strategies for these Hymenoptera.     

Multitrophic effects of experimental changes in plant diversity on cavity-nesting bees, wasps, and their parasitoids

Plant diversity changes can impact the abundance, diversity, and functioning of species at higher trophic levels. We used an experimental gradient in grassland plant diversity ranging from 1 to 16 plant species to study multitrophic interactions among plants, cavity-nesting bees and wasps, and their natural enemies, and analysed brood cell density, insect diversity (species richness), and bee and wasp community similarity over two consecutive years. The bee and wasp communities were more similar among the high (16 species) diversity plots than among plots of the lower diversity levels (up to 8 species), and a more similar community of bees and wasps resulted in a more similar community of their parasitoids. Plant diversity, which was closely related to flower diversity, positively and indirectly affected bee diversity and the diversity of their parasitoids via increasing brood cell density of bees. Increasing plant diversity directly led to higher wasp diversity. Parasitism rates of bees and wasps (hosts) were not affected by plant diversity, but increased with the diversity of their respective parasitoids. Decreases in parasitism rates of bees arose from increasing brood cell density of bees (hosts), whereas decreasing parasitism rates of wasps arose from increasing wasp diversity (hosts). In conclusion, decreases in plant diversity propagated through different trophic levels: from plants to insect hosts to their parasitoids, decreasing density and diversity. The positive relationship between plant diversity and the community similarity of higher trophic levels indicates a community-stabilising effect of high plant diversity.     

On a habitat structure-based approach to evaluating species occurrence: cavity-nesting Hymenoptera in a secondary tropical forest remnant

Measuring bee and wasp community habitat preferences in natural systems may provide insights for biodiversity management and conservation as habitat heterogeneity can be the major factor affecting species diversity in a community. Here, we present evidence that supports the use of a vegetation structure-based approach in order to predict the occurrence of common Brazilian-remnant solitary bee and wasp species. Using trap nests, we sampled Aculeate bees and wasps in a forest remnant within an urban area of southeast Brazil. We also measured eight habitat structure components in the area. Tree trunk circumference, shrub and wood log abundance were good predictors of presence or absence of the commonest solitary bee and wasp species in the study area. We demonstrated that even on a small scale it is possible to detect significant influences of habitat structural features on species occurrences and that some of them are effective as surrogates for predicting trap-nesting Hymenoptera occurrence in a given area. Our data present evidence on the potential application of a habitat structure-based approach in conservation assessments concerning cavity-nesting Hymenoptera. We caution, however, that this habitat structure-based approach must to be taken with prudence as a detailed survey of an area’s biodiversity is always preferable.     

Trap-nesting bees and wasps colonizing set-aside fields: succession and body size,management by cutting and sowing

Trap-nesting bees and wasps (Hymenoptera Aculeata) colonizing crop and fallow fields in an agricultural landscape were studied using 20 sown fields (pea, barley, rye, clover-grass mixtures, Phacelia tanacetifolia) and 20 fields with naturally developed vegetation (1- and 2-year old fields, both mown and unmown, and old meadows). Fourteen species of Apoidea, 4 of Sphecidae, 1 of Eumenidae and 4 of parasitoids were reared from reed nests exposed in these 40 fields of 10 field-types. Fields with naturally developed vegetation had twice as many species as sown fields, due to the distribution pattern of the 14 bee species, whereas the 9 predatory species (wasps and parasitoids) showed a rather uniform distribution. None of the trap-nesting bees were found in Phacelia fields, despite contrasting expectations of beekeepers. Old meadows showed a particularly high abundance and species richness, since only 10% of all traps were exposed, but 32% of all bee nests were sampled in old meadows, including 4 bee species that were not found elsewhere. Accordingly, species richness of fields with naturally developed vegetation showed a significant increase with age. Variability in Hymenoptera species numbers could be explained by corresponding differences in plant species numbers. The alternative hypothesis that field size or field connectivity influenced species richness was not supported. Habitats with great floral diversity appeared to offer better and richer food resources for the flower-visiting bees, whereas food availability apparently did not influence predatory wasps. The bees Osmia caerulescens and Megachile versicolor that had colonized early-successional fields took twice as long to provision cells as those that colonized late-successional meadows characterized by a greater plant species richness. In contrast, the eumenid wasp Ancistrocerus gazella took a similar period of time to provision cells in both field types. In addition, bee and wasp species of plant-species-poor fields were on average significantly larger than those of plant-species-rich fields. Thus, body size appeared to be a good predictor of colonization ability. Management by cutting greatly increased plant species richness in early-successional set-aside fields and thus doubled species richness of bees. Cutting of early-successional habitats can be expected to benefit insects and plants in general, whereas older grassland should show the greatest insect diversity when both mown and unmown parts are present.     

How can we preserve and restore species richness of pollinating insects on agricultural land?

During recent decades, concern about the loss of biodiversity on agricultural land has increased, and semi‐natural grasslands have been highlighted as critical habitats. Temperate European agricultural landscapes require distinct and appropriate management to prevent further impoverishment of the flora and fauna. This is especially urgent for pollinating insects that provide important ecosystem services. Our aim was to examine how species richness of three important groups of pollinating insects; solitary bees, butterflies and burnet moths are related to different farm characteristics, and if there are any differences between these three groups. A further aim was to test if red‐listed species are related to any farm characteristics. Species richness of solitary bees, butterflies and burnets was measured on all semi‐natural grasslands at 16 farms in a forest‐dominated area of 50 km² in southern Sweden, using systematic transect walks in April to September 2003 (only butterflies and burnets) and 2005. Species richness of solitary bees and butterflies was intercorrelated, both before and after controlling for the area of semi‐natural grassland. Species richness of solitary bees increased with the area of semi‐natural grassland. After controlling for the effect of the area of semi‐natural grassland species richness was strongly positively related with the density of the plant Knautia arvensis and negatively related with the proportion of grazed grassland. The results were similar for solitary bees and butterflies. The number of red‐listed solitary bees was positively related to the proportion of meadows with late harvest (after mid‐July) and decreased with increased farm isolation. The number of burnet species (all red‐listed) was positively related to vegetation height, flower density and the proportion of meadows with late harvest on a farm. Areas with a high density of K. arvensis and with traditional hay‐meadow with late harvest present, harbour most species. Promoting traditional hay‐meadows, late extensive grazing and the herb K. arvensis, people managing agricultural biodiversity can encompass high species richness of pollinating insects and support red‐listed species. Further, we suggest that the density of K. arvensis at a farm can be used as a biodiversity indicator, at least for pollinating insects.     

The Impact of Anthropogenic Disturbance on Assembly Patterns of Termite Communities

Intensification of land‐use threatens biodiversity, especially in tropical ecosystems that harbor the planet's highest species richness. This negative impact of anthropogenic disturbance on species numbers is well established, but the mechanisms underlying the community assembly processes are less well understood. Termites are of fundamental importance in tropical ecosystems where they are critical for nutrient recycling and species diversity. We tested the impact of anthropogenic disturbance on termite species diversity and assembly processes in a West African savanna applying the newest techniques of phylogenetic community analyses. Species richness dropped in areas of intensive land‐use and compositional similarity between intensive land‐use areas was high. This contrasted with a protected National Park where communities were characterized by high species richness and intermediate species turnover between sites. Slightly disturbed areas in the buffer zone surrounding the park were intermediate, they still had high species richness but similarity between sites increased. Strikingly, the assembly pattern also changed with disturbance from more phylogenetic overdispersion to more clustering (coexisting species became phylogenetically more similar), but only when the fungus‐growing termite Macrotermes bellicosus was absent. Our data suggest that the major forces structuring termite communities depend: (1) on the presence of this dominant mound‐building termite; and (2) that they change to more environmental filtering with disturbance. Anthropogenic disturbance seems to function as a filter that allows only a specific subset of species to occur. Such an effect might be widespread in ecology but it is difficult to document quantitatively. Phylogenetic community analyses can help to contribute such evidence.     

Spillover of trap-nesting bees and wasps in an urban–rural interface

A mismatch of resource availability in certain periods can lead to spillover of insects between habitats, resulting in temporal differences in insect diversity. Urban gardens are important anthropogenic habitats but it is unknown whether, when and why spillover of beneficial insects occurs between gardens and agricultural habitats. We used trap nests for Hymenoptera to monthly monitor bee and wasp abundance and species richness in 12 gardens and 12 rapeseed fields. Half of the gardens and rapeseed fields were located in the urban–rural interface and bordered each other (a garden paired with a rapeseed field) and the other half were isolated in the rural landscape (isolated rapeseed fields) and in the urban city centre (isolated gardens). In general, gardens in the urban–rural interface comprised the highest richness of bees and wasps. The abundance of bees but not of wasps was highest in paired habitats and peaked at full rapeseed blooming, indicating that mass-flowering rapeseed offers foraging resources for bees nesting in adjacent gardens. Thus, bees nest and increase their populations in both areas, benefiting from the mass-flowering resource in the agricultural habitat as well as the nesting resources from gardens, suggesting spillover of bees but not of wasps between paired gardens and rapeseed fields. Our study highlights the value of gardens in the urban–rural interface for the biodiversity of functionally important insects. Implementing urban gardening and small-scale agriculture in cities and suburban habitats can promote local pollinator populations and benefit adjacent croplands.     

Differences in endemic insect assemblages among vegetation types on a small island of the oceanic Ogasawara Islands

Natural vegetation is often replaced by invasive alien plants on isolated oceanic islands. To determine how invasive alien plants affect insect diversity, we compared flying insects captured using Malaise traps among different vegetation types on a small island (Nishijima; 0.49 km²) in the oceanic Ogasawara (Bonin) Islands in the north‐western Pacific. The numbers of individuals and species, and the species composition of pollinators (bees), predators (wasps) and wood borers (cerambycid, mordellid and elaterid beetles) were compared among three vegetation types: Casuarina equisetifolia (an invasive alien tree) forest, natural forest and natural grassland (forest edge), during two seasons (June and October–November 2005). In traps, 80.0, 66.7, 87.5, 85.7 and 100.0% of bee, wasp, cerambycid, mordellid and elaterid beetle species, respectively, were endemic to the Ogasawara Islands. Grassland had the highest wasp and bee species richness, whereas natural forest had the highest species richness of wood‐boring beetles. The C. equisetifolia forest had the poorest species richness for most insect groups (except mordellid beetles). More individuals of most insect groups (except bees) were captured in June than in October–November. More individual bees and wasps were captured in grassland than in forests, whereas more individual mordellid and elaterid beetles were captured in forests than in grassland. The number of cerambycid individuals did not differ among vegetation types. Redundancy analysis suggested that most insect species preferred natural forest or grassland to alien forest. Therefore, further invasion of natural grassland and forest by the alien tree C. equisetifolia may negatively affect the endemic insect fauna of Nishijima.     

The Influence of Historical Land Use and Water Availability on Grassland Restoration

The ecological role of historical land use has rarely been explored in the context of grassland restoration. We conducted a 4‐year field experiment in a steppe and an old field in Inner Mongolia in northern China to examine the influence of historical land use and water availability on ecosystem restoration. Species richness, evenness, and plant cover were higher in the steppe than in the old field. The steppe was more temporally stable compared with the old field in terms of species richness, evenness, plant density, and cover. Water addition increased peak aboveground biomass, belowground net primary productivity, species richness, plant density, and cover in both the steppe and the old field. Water addition also enhanced the stability of ecosystems and the restoration of grassland. Our findings suggested that historical land use determines community structure and influences the process of grassland restoration. Converting grasslands to farmland in semiarid areas can cause the long‐term loss of biodiversity and instability of ecosystem with consequent impacts on ecosystem services. The amendment of limited resources is an effective practice to increase the success of ecosystem restoration.     

Effects of habitat management on vegetation and above-ground nesting bees and wasps of orchard meadows in Central Europe

We studied the vegetation, stand structure and communities of above-ground nesting bees and wasps in 45 orchard meadows that were grazed, mown or abandoned (15 of each) in an agricultural landscape near Göttingen, Germany. Total species richness of plants was significantly lower and the proportion of dead wood was significantly higher on abandoned meadows compared to mown or grazed meadows. Species richness of bees, eumenid wasps and sphecid wasps did not differ between the three management types. Abundance of sphecid wasps was significantly higher on abandoned than on managed orchard meadows. Landscape context did not affect management type. The results suggest that management practises affect vegetation more significantly than the studied insect groups.     

Habitat type plays a greater role than livestock grazing in structuring shrubsteppe plant–pollinator communities

Livestock grazing is a widespread grassland disturbance and can negatively impact biodiversity. Pollinators constitute a vital component of grassland ecosystems, but the impact of grazing on pollinator diversity has seldom been evaluated in North America. We assessed vegetation structure, and pollinator and flowering plant abundance, richness, diversity, and community composition in four pairs of spring-grazed/ungrazed sites in south-central British Columbia, Canada. We also investigated whether pollinator or floral communities differed between the two threatened shrubsteppe habitat types we sampled—antelope-brush and big sagebrush shrubsteppe. Pan-trapping surveys captured 5907 bees, flies, beetles, wasps and butterflies constituting 253 species. We found that the percent cover of shrubs and bare soil increased with grazing, while the height of grasses and forbs decreased. In contrast, pollinator and flowering plant abundance, richness, diversity, and community composition were not significantly affected by grazing. Flowering plant and pollinator community composition did differ significantly between shrubsteppe habitats. Our results indicate that grasslands in North America, when managed responsibly, can maintain pollinator and flowering plant diversity under grazing pressure. The continued effort of land managers to balance ecological integrity and economic viability will be important for the conservation of grassland pollination systems.     

Trap-Nesting Hymenoptera and Their Network with Parasites in Recovered Riparian Forests Brazil

Different aspects of human activities can cause environmental change that endanger species persistence, alter species distributions, and lead to changes in antagonistic and mutualistic interactions, whereas deforestation and flooding of riparian forest results in landscapes consisting of patchily distributed riparian forest fragments in a matrix of pastures, plantations, and urban areas. Therefore, we assessed the richness, abundance, and trophic interactions of trap-nesting Hymenoptera and their parasites at four patches of restored riparian forest and at one reference natural fragment, of different sizes and ages, located at the Volta Grande Reservoir, in Minas Gerais and São Paulo states to answer the following questions: (1) Does the richness and abundance of cavity-nesting bees and wasps differ in riparian forest fragments according to the seasonal periods? (2) Does the composition of cavity-nesting bees and wasps vary among restoration and reference sites and between climate seasons (wet and dry)? (3) How do the degrees of specialization of the parasites vary among the patches of forest? We recorded 12 species of wasps, eight of bees, and nine species of parasites. Areas with longer time since restoration (reference site) showed higher species richness. However, the abundance was higher in most recent areas. The composition of bee and wasp assembly has not significantly changed between the climate seasons, although it is different between sampling areas. The richness and abundance were higher in warmer and rainy periods. The rate of bee and wasp mortality was high. The degree of specialization of parasites varies among sampling units, and the network of host-parasite interaction has a modular configuration with generalists and specialists. We concluded that the restored areas with more complex habitat could provide better conditions for the reestablishment of ecological interactions among these insects, the local flora, and other invertebrates, which together contribute to the success of the restored environments.     

Land‐use effects on the functional distinctness of arthropod communities

Land‐use change is a major driver of the global loss of biodiversity, but it is unclear to what extent this also results in a loss of ecological traits. Therefore, a better understanding of how land‐use change affects ecological traits is crucial for efforts to sustain functional diversity. To this end we tested whether higher species richness or taxonomic distinctness generally leads to increased functional distinctness and whether intensive land use leads to functionally more narrow arthropod communities. We compiled species composition and trait data for 350 species of terrestrial arthropods (Araneae, Carabidae and Heteroptera) in different land‐use types (forests, grasslands and arable fields) of low and high land‐use intensity. We calculated the average functional and taxonomic distinctness and the rarified trait richness for each community. These measures reflect the range of traits, taxonomic relatedness and number of traits that are observed in local communities. Average functional distinctness only increased significantly with species richness in Carabidae communities. Functional distinctness increased significantly with taxonomic distinctness in communities of all analyzed taxa suggesting a high functional redundancy of taxonomically closely related species. Araneae and Heteroptera communities had the expected lower functional distinctness at sites with higher land‐use intensity. More frequently disturbed land‐use types such as managed grasslands or arable fields were characterized by species with smaller body sizes and higher dispersal abilities and communities with lower functional distinctness or trait richness. Simple recommendations about the conservation of functional distinctness of arthropod communities in the face of future land‐use intensification and species loss are not possible. Our study shows that these relationships depend on the studied taxa and land‐use type. However, for some arthropod groups functional distinctness is threatened by intensification and conversion from less to more frequently disturbed land‐uses.     

Conserving biodiversity in a changing world: land use change and species richness in northern Tanzania

Even though human induced habitat changes are a major driver of biodiversity loss worldwide, our understanding of the impact of land use change on ecological communities remains poor. Yet without such information it is difficult to develop management strategies for maintaining biodiversity in the face of anthropogenic change. To address this gap, we explored how land use practices impacted species richness in a mammalian community in northern Tanzania. Using camera traps, we estimated the number of mammalian species inhabiting three land use types subjected to increasing levels of anthropogenic pressure: (1) Tarangire National Park, (2) pastoral grazing areas; and (3) cultivated areas outside the park. Results showed that land use practice is correlated with different levels of species richness. Interestingly, mammal species richness was highest in the grazing areas and lowest in cultivated areas. When we focused our analyses on carnivores, we found little significant difference in species richness between the park and pastoral grazing areas, however, carnivore richness were significantly lower in the cultivated areas. We found no significant link between species body weight and presence in the three areas considered. Altogether, our results show that biodiversity conservation can be achieved outside national parks, with pastoral grazing areas holding a significant proportion of mammal communities; however increasing cultivation of pastoral rangelands may represent a major threat to mammalian communities.