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Gauging the potential of urban environments as prospective insect pollinator habitat

Figlestahler, Jana (2018) BION02 20172
Degree Projects in Biology
Abstract
Within the last century, a continuous decline in global insect pollinator populations has been observed. The loss of pollinating insects is not only important for their conservation value in itself, but entails far-reaching consequences of pollination deficits. This development is mainly associated with anthropogenic environmental disturbances, leading to fragmentation and loss of natural habitats. In the future, solutions will be required, combining the interest of human food and habitat demand with biodiversity conservation. Across different land use types, pollinator species have been shown to benefit from garden habitats. We investigated the importance of land use type (urban and rural) and seasonal effect, on the support of... (More)
Within the last century, a continuous decline in global insect pollinator populations has been observed. The loss of pollinating insects is not only important for their conservation value in itself, but entails far-reaching consequences of pollination deficits. This development is mainly associated with anthropogenic environmental disturbances, leading to fragmentation and loss of natural habitats. In the future, solutions will be required, combining the interest of human food and habitat demand with biodiversity conservation. Across different land use types, pollinator species have been shown to benefit from garden habitats. We investigated the importance of land use type (urban and rural) and seasonal effect, on the support of biodiversity conservation in selected gardens within the city and surrounding areas of Malmö, Sweden. Pollination success was assessed through outcrossing wild plant and common garden crop species, using woodland strawberry (Fragaria vesca) and field bean (Vicia faba) respectively. Further we compared how proportionally varying scenarios of human population density and green cover within urban environments influenced seed set. Local parameters of flower and tree cover along with plant quality were incorporated into analyses, where solely plant quality was shown to account for variances within outcomes. Pollination success did not differ significantly across land use types, nor did we find population density or vegetation cover to have a significant impact, possibly highlighting overall insect pollination deficits. However, pollination rate varied with proceeding time, with a lower pollination rate found later in the season in both rural and urban landscapes. As successful pollination of plant species necessitates pollinator trait suitability, in future research, a wider range of varying plant species should be investigated in the two landscape types, to take into consideration species-specific responses across seasons. (Less)
Popular Abstract
Pollinators, making the most of city life?


When thinking of cities, with their large areas of sealed surfaces and small patches of remnant vegetation, thriving communities of pollinating insects may not be the first thing that comes to mind. However, urban environments increasingly come into focus for their potential to provide suitable habitat for pollinators that are today facing a number of threats. Increased management intensity within both rural and urban landscapes impairs quantity and quality of pollinator forage and nesting resources. A loss of pollinators negatively influences the reproduction of most plant species, including the food that we eat every day. It has been found that urban environments carry many advantages over... (More)
Pollinators, making the most of city life?


When thinking of cities, with their large areas of sealed surfaces and small patches of remnant vegetation, thriving communities of pollinating insects may not be the first thing that comes to mind. However, urban environments increasingly come into focus for their potential to provide suitable habitat for pollinators that are today facing a number of threats. Increased management intensity within both rural and urban landscapes impairs quantity and quality of pollinator forage and nesting resources. A loss of pollinators negatively influences the reproduction of most plant species, including the food that we eat every day. It has been found that urban environments carry many advantages over surrounding landscapes, such as a warmer climate, more stable flower availability throughout the year and lesser usage of pesticides. Could cities indeed have the ability to protect insect pollinators in the future?

I tested whether the pollination rate of woodland strawberry and field bean would differ between rural and urban habitats, assuming that pollination indicates pollinator abundance via their visits to flowers. Additionally, I looked at seasonal effects, as previous studies found agricultural landscapes to lack floral resource availability later in the season with urban areas providing complementary foraging opportunities. Lastly, within the city, it was investigated how human population density and vegetation cover influences pollination success.

The answer to whether cities could stabilize pollinator populations is a little more complex than a simple yes or no. The statistical evaluation did not show any significant differences between urban and rural sites, nor between the different urban categories. However, interpretation of trends suggested plant species differing in their pollination response towards land use types. Pollination success tended to be higher in urban environments for beans, and in rural environments for strawberries. Why could this be? Chosen plant species varied in their flower morphology; strawberries possess a more open flower than beans, with each attracting insect pollinators more adapted to either flower shape. Beans were thus likely pollinated by insects such as bumblebees, finding it easier to adapt to conditions found within the city, and strawberries by insects more commonly found in rural landscapes, for example hoverflies. This means that, yes, for some pollinator species, urban environments may be beneficial, but more research needs to be conducted in order to also address needs of land use change sensitive species. Against expectations, there was a decline in overall pollination success as the study progressed, possibly with weather and plant pest infestations as a cause, decreasing pollinator activity and plant health.

Additionally, interpretation of trends showed the overall pollinator community to be negatively influenced by high human population densities in urban environments, and a high vegetation cover to enhance pollination rate in areas of high population density - possibly mitigating its negative effects on pollination rate. With an ever-increasing human population, we need to further our understanding of the complexities surrounding the consequences for biodiversity to be able to implement such knowledge in future conservation planning. With careful consideration and attention, in the end perhaps there will be hope for pollinators to find a home in a busy world.



Master’s Degree Project in Biology, 45 credits, 2018
Department of Biology, Lund University

Advisor: Anna Persson
Conservation Biology, Department of Biology (Less)
Please use this url to cite or link to this publication:
author
Figlestahler, Jana
supervisor
organization
course
BION02 20172
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8939025
date added to LUP
2018-04-24 11:36:22
date last changed
2018-04-24 11:36:22
@misc{8939025,
  abstract     = {Within the last century, a continuous decline in global insect pollinator populations has been observed. The loss of pollinating insects is not only important for their conservation value in itself, but entails far-reaching consequences of pollination deficits. This development is mainly associated with anthropogenic environmental disturbances, leading to fragmentation and loss of natural habitats. In the future, solutions will be required, combining the interest of human food and habitat demand with biodiversity conservation. Across different land use types, pollinator species have been shown to benefit from garden habitats. We investigated the importance of land use type (urban and rural) and seasonal effect, on the support of biodiversity conservation in selected gardens within the city and surrounding areas of Malmö, Sweden. Pollination success was assessed through outcrossing wild plant and common garden crop species, using woodland strawberry (Fragaria vesca) and field bean (Vicia faba) respectively. Further we compared how proportionally varying scenarios of human population density and green cover within urban environments influenced seed set. Local parameters of flower and tree cover along with plant quality were incorporated into analyses, where solely plant quality was shown to account for variances within outcomes. Pollination success did not differ significantly across land use types, nor did we find population density or vegetation cover to have a significant impact, possibly highlighting overall insect pollination deficits. However, pollination rate varied with proceeding time, with a lower pollination rate found later in the season in both rural and urban landscapes. As successful pollination of plant species necessitates pollinator trait suitability, in future research, a wider range of varying plant species should be investigated in the two landscape types, to take into consideration species-specific responses across seasons.},
  author       = {Figlestahler, Jana},
  language     = {eng},
  note         = {Student Paper},
  title        = {Gauging the potential of urban environments as prospective insect pollinator habitat},
  year         = {2018},
}