„Urbanisation modulates plant-pollinator interactions in invasive vs. native plant species“ has been published in Scientific Reports. The article is open access.
In this article, we show that invasive black locust (Robinia pseudoacacia) is a “pollinator-friendly” tree and attracts not only honey bees but also wild bees and other wild pollinators. However, we also found that attractiveness of black locust decreases with increasing urbanisation.
Tree cover mediates the effect of ALAN on urban bats has been published in Frontiers in Ecology and Evolution. For Download, please go to the Frontiers Webpage.
Abstract: With urban areas growing worldwide, so does artificial light at night (ALAN) which negatively affects many nocturnal animals, including bats. The response of bats to ALAN ranges from some opportunistic species taking advantage of insect aggregations around street lamps, particularly those emitting ultraviolet (UV) light, to others avoiding lit areas at all. Tree cover has been suggested to mitigate the negative effects of ALAN on bats by shielding areas against light scatter. Here, we investigated the effect of tree cover on the relationship between ALAN and bats in Berlin, Germany. In particular, we asked if this interaction varies with the UV light spectrum of street lamps and also across urban bat species. We expected trees next to street lamps to block ALAN, making the adjacent habitat more suitable for all species, irrespective of the wavelength spectrum of the light source. Additionally, we expected UV emitting lights next to trees to attract insects and thus, opportunistic bats. In summer 2017, we recorded bat activity at 22 green open spaces in Berlin using automated ultrasonic detectors. We analyzed bat activity patterns and landscape variables (number of street lamps with and without UV light emission, an estimate of light pollution, and tree cover density around each recording site within different spatial scales) using generalized linear mixed-effects models with a negative binomial distribution. We found a species-specific response of bats to street lamps with and without UV light, providing a more detailed picture of ALAN impacts than simply total light radiance. Moreover, we found that dense tree cover dampened the negative effect of street lamps without UV for open-space foraging bats of the genera Nyctalus, Eptesicus, and Vespertilio, yet it amplified the already existing negative or positive effect of street lamps with or without UV on Pipistrellus pipistrellus, P. pygmaeus, and Myotis spp. Our study underpins the importance of minimizing artificial light at night close to vegetation, particularly for bats adapted to spatial complexity in the environment (i.e., clutter-adapted species), and to increase dense vegetation in urban landscape to provide, besides roosting opportunities, protection against ALAN for open-space foraging bats in city landscapes.
Working at the Charles Darwin Research Station again
Thanks to a research fellowship sponsored by the Schimper Stiftung I was able to go to the Galápagos in February. It was great to continue my work on the Scalesia restoration project in the highlands of Santa Cruz. After intensive work in the invertebrate lab we finished all spider and beetles identifications and counted all other invertebrates caught within the long-term monitoring. This program started in 2014 and invertebrates were caught in 34 plots using pitfall and Malaise traps. First results have been recently published but more detailed analyses will be available soon.
Scalesia pedunculata – an endemic tree in the Galápagos
Argiope spec. – a spider species commonly found in Scalesia trees
Connectivity or area – what drives plant species richness in habitat corridors? has been accepted in Landscape Ecology.
Authors Thiele J, Kellner S, Buchholz S & Schirmel J
In a nutshell, we found out that connectivity is more important for plant species richness in linear landscape elements than area. In particular, the richness of plant species that are dispersal limited and confined to semi-natural habitats benefits from connective networks of linear landscape elements in agricultural landscapes.
Abstract Urban wastelands are considered to be valuable habitats for biodiversity conservation, but empirical evidence for several poorly investigated taxa such as grasshoppers is still pending – although urgently required for reasonable habitat management and urban planning. For the first time, we analysed grasshopper diversity of urban wastelands at different diversity levels, namely, alpha and functional diversity. In 2014, we selected 24 urban wastelands in the city of Berlin (Germany).
Urban wasteland harbouring a Calliptamus italicus population
We analysed the relationships between local and landscape factors and different measurements of diversity (species richness, Simpson diversity, functional dispersion, functional evenness and functional divergence). We sampled 21 species, which represented about 45% of the entire grasshopper fauna of Berlin and numerous species of conservation interest were present at the investigated sites. Grasshopper diversity was best explained by local factors, with herb cover having a positive effect on alpha and functional diversity. Human impact and accessibility increased the conservation value of urban wasteland sites.
Late successional stages are very important for a high grasshopper diversity in general but early stages are mandatory to promote species of conservation concern. Urban wastelands can be turned into most promising transition zones for city-dwellers that fulfil the needs of conservationists and specialised species at the same time. To achieve this goal we recommend minimum requirements for successful habitat management.
The German Society of general and applied Entomology (DGaaE) and the German Scientific Society for Plant Protection and Plant Health (DPG) organised a conference on insect diversity in cities (III. Urbane Pflanzen Conferenz). I contributed a talk on habitat function of urban meadows for wild bees with emphasis on urbanisation effects (see Abstract in German). Due to a very diverse audience with many relevant stakeholders and decision-makers (e.g. scientists, gardeners, landscape planners, landscape architects, authorities and NGOs) it was possible to elaborate this topic from different perspectives. At the end we had very interesting – sometimes controverse – discussions to develop recommendations how to make cities more insect friendly and to comment on the new white book „Grün in der Stadt“ which was recently send out for preview. The official presentation of the white book will be in May 2017.
Authors Schirmel J, Thiele J, Entling MH & Buchholz S
Abstract Agricultural intensification is a cause of global biodiversity decline. Seminatural linear landscape elements (LLE) within agricultural landscapes can considerably mitigate these declines, but their effects on functional properties of biodiversity are poorly known. We analyzed trait composition and functional diversity (functional dispersion) of spiders and carabids in woody and herbaceous LLE. We expected that species assemblages of woody LLE are more diverse and K-selected compared to herbaceous LLE, and that effects of environmental parameters vary between LLE types. We selected 58 LLE in an agricultural landscape in Northwest Germany. We sampled carabids and spiders by pitfall trapping and measured landscape connectivity, landscape-wide land-use diversity, local land-use diversity, and local plant richness as explanatory variables. The trait composition of arthropods in woody LLE was more K-selected (lower dispersal ability, a higher food specialization or trophic level) than in herbaceous LLE. Moreover, spider functional diversity was higher in woody LLE. Spider functional diversity and proportion of predatory carabids in woody LLE increased with increasing connectivity of the habitats. In contrast, in herbaceous LLE local plant richness and landscape-wide land-use diversity were most important drivers for spider and carabid diversity and traits. Our results show that species richness and functional diversity of spiders and carabids were differently affected by landscape and local factors. Therefore, the importance of landscape connectivity was higher in woody LLE, suggesting that their inhabitants are more sensitive to habitat fragmentation than the highly mobile generalist species living in herbaceous habitats.
Disentangling urban habitat and matrix effects on wild bee specieshas been published in PeerJ.
Authors Fischer LK, Eichfeld J, Kowarik I & Buchholz S
Abstract In face of a dramatic decline of wild bee species in many rural landscapes, potential conservation functions of urban areas gain importance. Yet effects of urbanization on pollinators, and in particular on wild bees, remain ambiguous and not comprehensively understood. This is especially true for amenity grassland and extensively managed wastelands within large-scale residential housing areas. Using Berlin as study region, we aimed to investigate (a) if these greenspaces are accepted by wild bee assemblages as foraging habitats; (b) how assemblage structure of bees and individual bee species are affected by different habitat (e.g., management, flower density) and urban matrix variables (e.g., isolation, urbanization); and (c) to what extend grassland restoration can promote bees in urban environments. In summer 2012, we collected 62 bee species belonging to more than 20 % of the taxa known for Berlin. Urbanization significantly affected species composition of bees; 18 species were affiliated to different levels of urbanization. Most bee species were not affected by any of the environmental variables tested, and urbanization had a negative effect only for one bee species. Further, we determined that restoration of diverse grasslands positively affected bee species richnesss in urban environments. We conclude that differently structured and managed greenspaces in large-scale housing areas can provide additional foraging habitats and refuges for pollinators. This supports approaches towards a biodiversity friendly management within urban regions and may be of particular importance given that anthropogenic pressure is increasing in many rural landscapes.
Biodiversity functions of urban cemeteries: evidence from one of the largest Jewish cemeteries in Europe has been accepted for publication in Urban Forestry & Urban Greening.
Authors Kowarik I, Buchholz S, von der Lippe M & Seitz B
Abstract As the world becomes more urbanized, urban cemeteries may become increasingly valuable for biodiversity conservation as cemeteries are ubiquitous elements of the green infrastructure in cities worldwide. By implementing a multi-taxon approach at different spatial extents, we analyzed habitat functions of a large urban cemetery in Berlin (Weißensee Jewish Cemetery) and explored related environmental variables. This cemetery is an outstanding cultural heritage site but it also stands for old urban cemeteries that have progressed to urban woodland, an ecosystem type that exists in many regional and religious contexts. The cemetery provided a habitat for 604 species; species of conservation concern comprised 1.6–100% of total species among different groups of taxa (in decreasing order: bats, birds, lichens, bryophytes, carabids, vascular plants, spiders). Species richness and species composition at the plot level were significantly related to differences in management intensity and resulting vegetation structures but differed among taxonomic groups. In vascular plants, carabids and spiders, the species composition varied significantly with habitat age, and there was a set of characteristic species for different age classes in each species group. Our results thus support the use of differentiated management approaches to maintain habitat heterogeneity by allowing wilderness development in some parts of a cemetery while keeping others more open. Since these aims can be combined with efforts to preserve outstanding grave architectures and allow access to visitors, our study indicates ways of reconciling conflicting aims of heritage preservation and biodiversity conservation, a promising perspective for biodiversity conservation in culturally shaped urban landscapes. We conclude that cemeteries provide important cultural ecosystem services within the urban green infrastructure.