Bees in urban community gardens : local versus landscape determinants

• Main Author: Latus, Jessica
• Other Authors: Helsingin yliopisto, Bio- ja ympäristötieteellinen tiedekunta, Ympäristötieteiden laitos, University of Helsinki, Faculty of Biological and Environmental Sciences, Department of Environmental Sciences, Helsingfors universitet, Bio- och miljövetenskapliga fakulteten, Miljövetenskapliga institutionen
• Format: Master Thesis
• Language: English
• Published: Helsingfors universitet 2014
• Subjects: urban ecology; urban bees; community gardens; local and landscape effects; pollinator conservation; Fennoscandia
• Online Access: http://hdl.handle.net/10138/136451

Urbanization is occurring at rapid rates worldwide. While the effects of urbanization are numerous, those on wildlife are of utmost concern in the continued fight for biodiversity conservation. Specifically, the focus on global pollinator declines is of interest due to the interconnectedness between pollinators and plant communities. It is feared that urban areas could become dead zones to these species, specifically bumblebees. Bumblebees are one of the native pollinators of Finland, and therefore were the focus of this study, which was conducted in Helsinki (southern Finland). This project's focus was on the influence of both local (i.e. flowering resources) and landscape (i.e. levels of urbanization) features on bumblebee communities. More specifically, I was interested in the effects of urbanization on bumblebee abundance and species richness. To study this question, community gardens (allotment gardens) were used as study sites along a gradient of urbanization from low to high (chosen by GIS mapping of the levels of impervious surfaces within 500 m of the sites). It is thought that these greenspaces could function as habitat for bumblebees in cities. This study was conducted during the summer of 2013 in 12 community gardens across the city of Helsinki. Two methods to survey bee populations were utilized, pan traps as well as sweep netting. Furthermore, a vegetation analysis was conducted to assess the level of resources present within the gardens, while GIS was used to measure a set of landscape variables in and around each garden. At the end of the season (June to September) the bees were identified and Generalized Linear Mixed Effects models were used to analyze the data. This study found that local variables more strongly predicted both bee abundance and species richness. Even though landscape variables were not strong predictors, this does not make them irrelevant in future conservation strategies. However, it is thought that as long as community gardens are planted appropriately (i.e. native flowers) ...