Honey bees in beehive: new research shows that land use change affects short-tongued bumblebees different from solitary wild bees. Photo: J. Lokrantz/Azote

To bee or not to bee?

New insights into how urbanisation affects different bee pollinators.

Centre researcher Åsa Jansson has previously shown the importance of including ecosystem services in wealth measurements.
In an article recently published in Ecology and Society, Jansson, together with Steve Polasky from the Beijer Institute, digs deeper into the links between biodiversity of wild bees and crop generation in the increasingly urbanised landscape of Stockholm.
“The main purpose of this paper is to use a series of relatively straightforward and fairly simple calculations to investigate the role of diversity within the functional group of pollinators for food security", Åsa Jansson explains.
Better apart
Today, about 5% of the arable land in the Stockholm County is used for growing economically important oil rapeseed. Although this is relatively small compared to other crops, there are still some hundred oil rapeseed fields in the landscape of the county that require pollination. Short- tongued generalist bumblebees supply the major part of this pollination, but many solitary bees also contribute, albeit not identical in their function.
Interestingly, the generalist pollinators tend to operate at a scale of 750 meters, whereas solitary wild bees have been shown to operate on a much smaller scale of 250 meters. Hence, the effect of land use change (i.e. fragmentation of the landscape) on these two types of pollinators is potentially different.
“Our calculations clearly show the importance of analyzing the solitary bee group separately to better understand the potential reduction in pollinator potential as the city of Stockholm continues to grow", Åsa Jansson says.
Negative effects on response diversity
In conclusion, when analyzing the role of biodiversity for food security in increasingly urbanised landscapes, a better resolution seems key. 
Only by studying the different bee species separately from the lumped wild pollinator group their potential contribution to the resilience of the landscape is revealed.

Hence, the results quantitatively show that there can be a substantial decrease in resilience due to negative effects on response diversity without detecting any immediate decrease in ecosystem service (pollination) generation over time, thus generating a sense of false security and sustainability.

One of the next possible steps, writes Jansson and Polasky, is to assess the economic value of the response diversity of bees and its contribution to resilience of food production.

Want to learn more?
See seminar with Professor Claire Kremen on pollination services and agroecosystems:

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Source: Jansson, Å., and S. Polasky. 2010. Quantifying biodiversity for building resilience for food security in urban landscapes: getting down to business. Ecology and Society 15(3): 20. [online] URL: http://www.ecologyandsociety.org/vol15/iss3/art20/


Jansson, Å., and S. Polasky. 2010. Quantifying biodiversity for building resilience for food security in
urban landscapes: getting down to business. Ecology and Society 15(3): 20.  www.ecologyandsociety.org/ vol15/iss3/art20/


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