Sustained functional composition of pollinators in restored pastures despite slow functional restoration of plants

California Native Perennials Attract Greater Native Pollinator Abundance and Diversity Than Nonnative, Commercially Available Ornamentals in Southern California

While many factors have been implicated in global pollinator decline, habitat loss is a key driver of wild pollinator decline in both abundance and species richness. An increase in and diversification of pollinator habitat, even in urban settings, can assist in the conservation of pollinator populations. In Southern California, a highly fragmented and urbanized landscape with a rich yet threatened native pollinator fauna, the availability of food resources for native pollinators hinges largely upon the selection of ornamental plants grown in the urban landscape. To examine the pollinator attractiveness of ornamental plants in a Southern California context, we installed an experimental garden with common California native and nonnative ornamental perennials and observed floral visitation and visitor community composition for 3 yr. Our study demonstrates that while native pollinators visited common ornamental perennials native to California at a higher rate than they visited nonnative ornamentals, introduced honey bees showed no significant preference for either native or nonnative species. Native plants also received a greater diversity of visitor taxa, including a richer suite of native bees. Plant species differed dramatically in attractiveness, by as much as a factor of 12, even within the native status group. Our results suggest that including a data-driven selection of both native and non-native ornamental perennials in the urban landscape can diversify the assemblage of native pollinators, provide critical floral resources throughout the year, and reduce the impact of honey bee landscape foraging dominance by providing plants highly attractive to native pollinators and less so to honey bees.

“Landscape of Stress” for Sheep Owners in the Swedish Wolf Region

Farmers who keep livestock in large carnivore areas are exposed to threat of predation directly impacting on finances and workload as well as the associated psychological stress indirectly impacting on farmers well-being. So far, little is known about such stress responses. The concept of “stress” or “stress reaction” is often used as an undifferentiated umbrella concept for the experience of negative emotional episodes. However, the stress reactions could be divided into cognitive, physiological, and behavioural aspects. This study aimed to develop and apply a theory-based approach to identify stress responses among sheep farmers in the Swedish “wolf-region.” A thematic analysis of interviews conducted with sheep farmers showed ample support for stress responses among the informants in relation to large carnivores and their management, although the interviews were conducted with a different focal topic. The findings support the idea that stress responses could be categorised into cognitive, physiological, and behavioural aspects. This distinction would help to identify and fully understand the cumulative impact of stress from the presence of large carnivores on farmers’ well-being.

Pollinator foraging flexibility mediates rapid plant-pollinator network restoration in semi-natural grasslands

We examined how plant-pollinator interactions were affected by time since habitat restoration and landscape connectivity by comparing plant-pollinator networks in restored, abandoned and continuously grazed semi-natural pastures in south-central Sweden. We measured richness of flowering plants and pollinators, and local plant-pollinator network characteristics including species composition as well as the number and identity of interactions, allowing a deeper understanding of species and interaction beta diversity. Pollinator richness and abundance were highest in restored grasslands. They successfully resembled continuously grazed grasslands. However, the turnover of interactions was extremely high among pasture categories (0.99) mainly due to high turnover of plant (0.74) and pollinator species (0.81). Among co-occurring plant and pollinator species, the turnover of interactions (0.66) was attributable mainly to differences in the number of links and to a lesser extent to species true rewiring (~0.17). Connectivity and time since restoration had no effect on the measured network properties. We show that plant-pollinator interactions can be rapidly restored even in relatively isolated grasslands. This is partly due to flexibility of most pollinators to establish interactions with the available flowering plants and relatively high species interaction rewiring, indicating that pollinators behavioural plasticity allow them to shift diets to adapt to new situations.

Facing the future for grassland restoration - What about the farmers?

In line with the 2010 Aichi Convention for Biological Diversity, the European Union has a goal to restore 15% of degraded ecosystems and their services by the year 2020 (target 2, Europe 2020). This includes restoration of semi-natural grasslands (SNGs). Management of both intact and restored SNGs is dependent on people's willingness to manage them. Due to low profitability, management abandonment still occurs all over Europe, which highlights the need to raise farmers' and landowners' perspectives. In this study, we combined survey data and in-depth interviews with farmers/landowners managing previously restored SNGs, to understand how they perceive the restoration process, the outcome and future management. Survey and interview data were analysed in relation to biodiversity and Agri-environmental payments data from the restored sites. Almost all respondents considered the restoration successful and the re-inventoried restored SNGs also showed an increase in plant diversity. Nevertheless, 10% of the restored SNGs were abandoned again post-restoration and 40% of the respondents were unsure if they would continue the management in the future. Abandoned management may cause a negative trend in terms of decreased biological, cultural and aesthetic values, in the local community, as well as for the society in general. Most respondents explained a strong dependency on Agri-environmental payments, both as a restoration incentive and for post-restoration management. Also non-financial support from authorities in form of feedback and advice was requested, as well as support from the local community and society as a whole. Future management in a longer time perspective was strongly coupled to the farm economy, i.e. received Agri-environmental payments at farm-level and profit from selling agricultural products, and whether the farmers had successors. We conclude that both social and ecological factors, here farm economy, authority support and proper management, must be in place for long-term success of grassland restoration.

Sustained functional composition of pollinators in restored pastures despite slow functional restoration of plants

Habitat restoration is a key measure to counteract negative impacts on biodiversity from habitat loss and fragmentation. To assess success in restoring not only biodiversity, but also functionality of communities, we should take into account the re-assembly of species trait composition across taxa. Attaining such functional restoration would depend on the landscape context, vegetation structure, and time since restoration. We assessed how trait composition of plant and pollinator (bee and hoverfly) communities differ between abandoned, restored (formerly abandoned) or continuously grazed (intact) semi-natural pastures. In restored pastures, we also explored trait composition in relation to landscape context, vegetation structure, and pasture management history. Abandoned pastures differed from intact and restored pastures in trait composition of plant communities, and as expected, had lower abundances of species with traits associated with grazing adaptations. Further, plant trait composition in restored pastures became increasingly similar to that in intact pastures with increasing time since restoration. On the contrary, the trait composition of pollinator communities in both abandoned and restored pastures remained similar to intact pastures. The trait composition for both bees and hoverflies was influenced by flower abundance and, for bees, by connectivity to other intact grasslands in the landscape. The divergent responses across organism groups appeared to be mainly related to the limited dispersal ability and long individual life span in plants, the high mobility of pollinators, and the dependency of semi-natural habitat for bees. Our results, encompassing restoration effects on trait composition for multiple taxa along a gradient in both time (time since restoration) and space (connectivity), reveal how interacting communities of plants and pollinators are shaped by different trait-environmental relationships. Complete functional restoration of pastures needs for more detailed assessments of both plants dispersal in time and of resources available within pollinator dispersal range.