More than half of the world's population lives in urban areas, a proportion that is expected to increase. Even if urbanisation is widely regarded as a major threat to global biodiversity, recent research highlighted the potential ecological importance of cities for pollinators. Key determinants of cities' ability to sustain pollinators are the presence of green areas and the connectivity between them. However, temperature is also expected to be of primary importance for pollinator activities. In light of that, a new Safeguard co-written paper
, published in the Insect Conservation and Diversity
, aims at disentangling the effects of temperature, open habitat cover, and distance from the city centre on wild bee communities in the city of Rome (Italy).
Thus, in the newly published ‘Temperature and not landscape composition shapes wild bee communities in an urban environment
’, the researchers, amongst whom Safeguard partners of the University of Padua
, sampled wild bee communities using pan-traps for 4 months. They studied 36 sites along two statistically independent gradients of temperature and open habitat cover for the purpose of the study. The researchers concluded that, in a highly urbanised environment, such as the metropolitan city of Rome, wild bee abundance and diversity did not change in response to open habitat cover or distance from the city centre. In contrast, temperature was the main driver shaping wild bee communities.
The scientists believe that under future global warming, the heat-tolerant wild bee species will benefit from increasing temperatures in urban settlements and that warm temperature communities will be dominated by polylectic and small-bodied bees. Further research is needed to understand the potential role of cities as pollinator refuge under global change, focusing not only on wild bees, but even on other fundamental pollinator taxa such as Coleoptera, Diptera, and Lepidoptera.
Read the full paper here.
Photo: Study area in the city of Rome, Italy (a); spatial distribution of the 36 selected sampling sites (black points) along a gradient of urbanisation (shaded) (b); and example of open green habitat cover (in green) in a 500 m buffer (c). The centroid of the buffer is the point where pan-traps were placed.
Source: Maps were obtained from OpenLayers Plugin, QGIS