Multifunctional flower strips - does such a thing exist?

(Poster)

Lovisa Nilsson
lovisa.nilsson@cec.lu.se

Centre for Environmental and Climate Research, Lund University, Sweden
,
Björn Klatt
Department of Biology, Lund University, Sweden
,
Henrik Smith
Centre for Environmental and Climate Research, Lund University Department of Biology, Lund University, Sweden

DOI: 10.17011/conference/eccb2018/107538

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Agricultural production is one of the key drivers of biodiversity loss in the world, and as a consequence of this some ecosystem services that are important for crop production are threatened. There is a plethora of different agri-environmental/conservation measures taken to counter the biodiversity losses in agricultural landscapes, some better supported by evidence than others. One of these measures is flower strips adjacent to crop fields. Flower strips have mainly been proposed to support pollinators and pollination of crops (Jönsson et al., 2015) but may also support natural enemies and natural biological control of pests (Tschumi et al., 2015). However, the role of flower strips for biodiversity per se remains controversial. It has been suggested that they mainly support the relatively common species providing ecosystem services, and not rarer species in need of conservation measures (Wood et al., 2016). Further, most studied flower strips target only one organism group or ecosystem service. We suggest that the seed mix in the flower strip is an important determiner for which species it attracts. In this study, annual flower strips with a flower mixture tailored to attract both pollinators and natural enemies were sown on 12 different farms in a high intensively farmed area in southern Sweden. Effects of the flower strips for different organism groups were measured at different spatial scales after flowering of oilseed rape, when agricultural landscapes are usually lacking nectar and pollen resources. We measured the presence and abundance of pollinators (wild bees and hover flies) and natural enemies in the flower strips. We also sampled natural enemies and aphids in the adjacent wheat field, at several different distances from the field edge. Colonies of bumble bees (Bombus terrestris) were placed at different distances from the flower strips and their fitness assessed. With these different methods, we aim to get a comprehensive picture of how an annual flower strip, tailored to attract both pollinators and natural enemies, affect both common and rare species in the different organism groups at a landscape scale. Preliminary results show that the fitness of the bumble bee colonies declined sharply with their distance to the flower strips, solely, but also in interaction with the size of the flower strips and the proportion of agricultural land. Further analyses will show how wild bees and hoverflies as well as natural enemies and pest control were affected by the presence of and distance to a flower strip. The results from this study will expand our knowledge about flower strips as a conservation measure. It will teach us more about the potential of flower strips tailored to benefit not only one organism group but several. We will also learn more about the potential of annual flower strips to benefit rare species.

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INTRO:
The authors report on an impressively thorough field study focusing on multiple functions of flower strips located adjacent to crop fields. They describe how several potential effects of flower strips were simultaneously included in the study design, report some first results and discuss the results that are still expected from this widely interesting empirical study.
MERITS:
This is a timely study on conservation of biodiversity and ecosystem services in agricultural landscapes. I think that the main merit of the study is its exceptionally comprehensive study design in investigating several kinds of effects of flower strips simultaneously in agricultural landscapes. Flower strips have received much attention as an easily applied and effective conservation measure to promote especially pollinators in agricultural landscapes, but here the authors have studied effects also on natural enemies, and separately on rarer species at the same time. Additional strengths include the replication of the study in several landscapes and the used experimental approach to study the effects of flower strips on the fitness of bumblebee colonies.
CRITIQUE:
No critique
DISCUSSION:
I believe that this well-designed study may become an important one in its field. I am curious to hear more about the study and its results in the congress, hopefully as an oral presentation.

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INTRO:
The study concerns the functioning of flower strips. Planting flower strips is the farming practice that may promote biodiversity and ecosystem services on cultivated lands by providing resources for arthropods beneficial for agricultural crops cultivation. Specific mixture of annual flowers was sown on 12 farms to study the effects of the strips for two groups of arthropods - pollinating insects and natural enemies. Preliminary results show positive effect of the strips on bumble bee colonies. The Authors promise further interesting analyses considering the effect of the strips on various pollinators, pests and their enemies. This study may contribute to filling knowledge gaps regarding the extent to which planting flower strips may be beneficial for various arthropods and agricultural crops cultivation.
MERITS:
The study adds knowledge about extent to which planting flower strips may be beneficial for environment and for agricultural crops cultivation. The Authors presented very interesting suggestion that "seed mix in the flower strip is an important determiner for which species it attracts". Taxonomic composition of flower strips seems to be underestimated, yet important factor influencing usability of this farming practice.
CRITIQUE:
Considering that the abstract concerns a conference presentation, I do not find any weakness in the abstract.
DISCUSSION:
Wildflower strips have been introduced to promote and enhance diversity of arthropods, especially pollinating insects and pest enemies, on arable lands. However, such efforts are taken quite superficially; the drivers of success or failure of the strips are not clearly identified and not known to farmers. As the Authors said: "the role of flower strips for biodiversity per se remains controversial".

The Authors suggested that the seed mix in the flower strip may influence the success of the strip, because specific mix would attract specific insect species. Indeed, simple enhancement of biodiversity should not be seen as the key effect resulting from sowing wildflower strips. These enhancements, if appreciated and willingly used by farmers, should serve specific ecosystem services, profitable for the farmers. Therefore, the strips should attract specific species of arthropods, beneficial for cultivated crops. In this context, presented study have important implications and may lead to a better farming practice profitable for both farmers and the environment. Additionally, the study forms a coherent whole with other ECCB 2018 abstracts considering flower strips and adds interesting point of view on the functioning and management of this farming practice.

The Authors presented only preliminary results, but they promised further analyses utilizing wild bees, hoverflies and natural enemies of pests. I believe this study is valuable and interesting contribution to the ECCB 2018 conference.

Multifunctional flower strips - does such a thing exist?