Pollinating animals in the urban environment

Urban environments contain habitats for flowering plants and their pollinating animal species. It is, however, unclear how the urban matrix influences plant-pollinator processes. We recorded plant diversity, floral abundance, flower visitor diversity and plot visits at 89 plant patches within the city of Zürich. The urban matrix surrounding each site was analyzed for the landscape metrics edge density and the extent of green area up to 200m radius. The correlation between edge density and bee diversity and visitation frequency varied over the entire spatial range, while the correlation for syrphid diversity and visitation frequency levelled off at 80m radius. In contrast, the correlations with green area were more consistent, with bee diversity levelling off after 100m, while syrphid diversity and visits continued to increase. The variation in the correlation of bee visits was partly accounted for by the large contribution of honeybees. Plant diversity significantly affected bee diversity and visits, and syrphid visits. Floral abundance had a positive effect on bee visits and bee diversity. Syrphid diversity had a negative interaction with floral abundance and green area. The extent of green area increased bee diversity and visits, and syrphid visits, while edge density reduced visitation by bees. This study showed that plant diversity and floral abundance in urban environments promote pollinating flower visitors. The extent of green area and edge density are important urban mosaic attributes that affect pollinator abundance and visitation frequency at multiple scale

Geographic variation in the morphology and behavioural ecology of a sphecid wasp

A comparative study between populations of Mellinus arvensis (Hymenoptera: Sphecidae) was carried out in Britain. Large variations in size were found between populations and these were correlated with environmental, thermal, and biological factors. A latitudinal dine accounted for some of the variation, with larger wasps found at southerly locations. This was partially explained by climatic patterns and wasp warm-up rates. A hypothesis involving the interaction of environmental, behavioural and morphological factors was suggested to account for the remaining unexplained size variation between populations. It was found that at sites where the ground is compact and difficult to dig through, nests are more valuable in terms of time required to dig them. A strategy of searching for rather than digging a nest becomes viable. Wasps do not seem to be able to distinguish between occupied and abandoned nests, and aggressive interactions at nests occur between wasps searching for a nest and the nest residents. Aggression is more frequent at sites where pressure from searchers is greatest, that is, at sites where nest construction is most difficult and costly. Consequently, large wasps, which have greater success in aggressive encounters, are selected for at these sites. At sites where the ground is loose and easy to dig through, a more successful reproductive tactic appears to be maximisation of offspring number, resulting in many, small offspring. Behavioural observations suggested that M. arvensis is capable of, at least, limited endothermy, although this could not be confirmed in laboratory experiments. Similar observations and results were obtained from several other sphecid species. However, endothermy was found in two sphecid species of the genus Bembix in Portugal, suggesting that endothermy may be more widespread than previously thought

Genetic variation and plant performance in fragmented populations of globeflowers ( Trollius europaeus ) within agricultural landscapes

The management of remnant populations in highly fragmented landscapes requires a thorough understanding of the processes shaping population persistence. We investigated relationships between population characteristics (i.e. size, density and pollinator abundance), offspring performance, genetic diversity and differentiation in Trollius europaeus, a plant with a nursery pollination system. In 19 populations of different sizes and located in north-east Switzerland, an area which has undergone widespread land use changes over the last decades, we assessed neutral genetic diversity (N total=383) using AFLPs and plant performance in a greenhouse experiment (N total=584) using competition and control treatments. Overall genetic differentiation was low (F ST=0.033) with a marginal significant isolation by distance effect (P=0.06) indicating (historical) genetic connectivity among the populations. Mean expected heterozygosity was H E of 0.309 (0.0257-0.393) while inbreeding coefficients (F IS) were significant in only three populations. Genetic diversity was not related to population size, plant density or pollinator abundance. Plant performance was reduced under competition (P<0.001) but the severity of competition was independent of genetic diversity and population size. In summary, remnant populations of T. europaeus retain genetic diversity and seem capable of persisting under the present conditions within an agricultural matrix. T. europaeus is a perennial herb, thus it may require several generations for the negative effects of fragmentation and isolation to manifest. Our findings indicate that small populations are as important as large populations for the conservation and management of genetic resource

Der Einfluss der Honigbienen auf Pflanzen-Bestäuber-Netzwerke in den Schweizer Alpen

Der kontinuierliche Rückgang der Landwirtschaftsfläche in der Schweiz führt dazu, dass die verbleibenden Flächen bei einem jährlichen Einsatz von 2200 t Pestiziden zunehmend intensiver und in grösseren Einheiten bewirtschaftet werden. Die heute dominierenden, an Blütenpflanzen und Kleinstrukturen armen «grünen Wüsten» bieten kaum noch Nahrung für Honigbienen. Der intensive Einsatz von Pestiziden und die geringen Nahrungsressourcen schwächen die Honigbienen. In Verbindung mit einem Befall durch die Varroa-Milbe kann dies zur Erkrankung der Bienen und zum Tod ganzer Völker führen. Die Schweizer Bundesverwaltung ist dabei, Massnahmen zur Förderung der Honigbienen 3 auszuarbeiten. Bis diese Massnahmen greifen, könnten Imker ihre Völker zur Stärkung in die Schweizer Alpen verlegen, wo mehr extensiv bewirtschaftete Flächen und Nahrungsquellen vorhanden sind. Vor diesem Hintergrund wurde untersucht, welchen Einfluss Honigbienen in den Alpen auf die einheimischen Pflanzen-Bestäuber-Netzwerke haben

Development of polymorphic microsatellite markers of the endangered and endemic Vateriopsis seychellarum (Dipterocarpaceae), a relict canopy tree of the Seychelles

The Dipterocarpaceae are a globally significant family of tropical timber trees. They are especially dominant in lowland rainforests of Southeast Asia, but have a pan tropical distribution. Vateriopsis seychellarum is the sole representative of this family on the Seychelles. Historically one of the dominant canopy trees on Mahé, extensive overexploitation of this species for its timber has led to its virtual extinction. The last individuals of this species are found in small fragmented populations at lower altitudes (up to 400m) on the island of Mahé where the total number of known reproductive adults is 112. We developed ten polymorphic microsatellite loci for this species to enable us to quantify the levels of diversity in remnant populations and to study genetic structure and contemporary gene flow. In addition we tested for cross amplification of these alleles in the closely related but geographically disjunct species Vateria indica. In Vateriopsis seychellarum the number of alleles per locus ranged from 6 to 20 (mean of 11.4 per locus) with an average polymorphic information content of 0.73 across loci. Expected heterozygosity ranged from 0.40 to 0.71 with 3 of the 10 loci showing deviation from Hardy-Weinberg expectations. 8 of the 10 primers showed cross amplification in Vateria indica. These markers will help to provide a better understanding of the significance of historic distributions, gene flow and recent anthropogenic habitat degradation for the survival of widespread species in recently fragmented landscape

Glocal woodlands – The rescaling of forest governance in Scotland

As a response to global crises of climate change and biodiversity loss, the UN has called for restoring a billion hectares of land. In recognition, both governments and the private sector have pledged to restore landscapes through planting millions of hectares of forests. Private sector investment is to play a critical role in meeting these goals, through instruments such as biodiversity offsetting, philanthropy, voluntary carbon markets, sustainability funds, and climate bonds. Such instruments allow for the value of place-based ecosystems, such as standing forests, to be circulated globally. No longer are forests horizontal (in terms of their extent on a map); they are also vertical, in terms of their entanglements with institutions, and actors, operating at various scales. An overarching emphasis on the private sector however obscures the role of state institutions in engaging these multi-scalar institutions and actors. Bringing the dimension of scale to tree planting, we examine the ways in which woodland creation, a ‘national’ policy priority for the Scottish government, brings together actors, both ‘local’ and ‘global’, in an unequal context. Our analysis uncovers that in retreating from directly creating and managing woodlands to playing a supportive regulatory role, Scottish Government’s forest policies increasingly rescale forest and landscape governance to private and non-profit sectors, and to individual landowners and communities. These actors, who are differently endowed in terms of resources, participate in forestry developments on an uneven playing field. Moreover, questions around power and distribution of benefits arise as woodland expansion increasingly becomes part of green investment portfolios, environmental, social, and corporate governance (ESG) commitments, offsetting, and individual philanthropy. A relational view of scale that examines prevailing relations of power and resources in given socio-political contexts can both animate and inform current discourses and policies on tree planting for climate change mitigation

Glocal woodlands – The rescaling of forest governance in Scotland

As a response to global crises of climate change and biodiversity loss, the UN has called for restoring a billion hectares of land. In recognition, both governments and the private sector have pledged to restore landscapes through planting millions of hectares of forests. Private sector investment is to play a critical role in meeting these goals, through instruments such as biodiversity offsetting, philanthropy, voluntary carbon markets, sustainability funds, and climate bonds. Such instruments allow for the value of place-based ecosystems, such as standing forests, to be circulated globally. No longer are forests horizontal (in terms of their extent on a map); they are also vertical, in terms of their entanglements with institutions, and actors, operating at various scales. An overarching emphasis on the private sector however obscures the role of state institutions in engaging these multi-scalar institutions and actors. Bringing the dimension of scale to tree planting, we examine the ways in which woodland creation, a ‘national’ policy priority for the Scottish government, brings together actors, both ‘local’ and ‘global’, in an unequal context. Our analysis uncovers that in retreating from directly creating and managing woodlands to playing a supportive regulatory role, Scottish Government's forest policies increasingly rescale forest and landscape governance to private and non-profit sectors, and to individual landowners and communities. These actors, who are differently endowed in terms of resources, participate in forestry developments on an uneven playing field. Moreover, questions around power and distribution of benefits arise as woodland expansion increasingly becomes part of green investment portfolios, environmental, social, and corporate governance (ESG) commitments, offsetting, and individual philanthropy. A relational view of scale that examines prevailing relations of power and resources in given socio-political contexts can both animate and inform current discourses and policies on tree planting for climate change mitigation.ISSN:0264-8377ISSN:1873-575

Uncertainties in the value and opportunity costs of pollination services

Pollination is an ecosystem service that directly contributes to agricultural production, and can therefore provide a strong incentive to conserve natural habitats that support pollinator populations. However, we have yet to provide consistent and convincing pollination service valuations to effectively slow the conversion of natural habitats. We use coffee in Kodagu, India, to illustrate the uncertainties involved in estimating costs and benefits of pollination services. First, we fully account for the benefits obtained by coffee agroforests that are attributable to pollination from wild bees nesting in forest habitats. Second, we compare these benefits to the opportunity cost of conserving forest habitats and forgoing conversion to coffee production. Throughout, we systematically quantify the uncertainties in our accounting exercise and identify the parameters that contribute most to uncertainty in pollination service valuation. We find the value of pollination services provided by one hectare of forest to be 25% lower than the profits obtained from converting that same surface to coffee production using average values for all parameters. However, our results show this value is not robust to moderate uncertainty in parameter values, particularly that driven by variability in pollinator density. Synthesis and applications. Our findings emphasize the need to develop robust estimates of both value and opportunity costs of pollination services that take into account landscape and management variables. Our analysis contributes to strengthening pollination service arguments used to help stakeholders make informed decisions on land use and conservation practices. © 2019 The Authors. Journal of Applied Ecology © 2019 British Ecological Societ