Master thesis in Sustainable Development 2019/39 Examensarbete i Hållbar utveckling The Potential of Living Walls to Host Pollinator Habitat Shirin El Ghomari DEPARTMENT OF EARTH SCIENCES INSTITUTIONEN FÖR GEOVETENSKAPER Master thesis in Sustainable Development 2019/39 Examensarbete i Hållbar utveckling The Potential of Living Walls to Host Pollinator Habitat Shirin El Ghomari Supervisor: Ann-Mari Fransson Subject Reviewer: Christine Haaland Copyright © Shirin El Ghomari and the Department of Earth Sciences, Uppsala University Published at Department of Earth Sciences, Uppsala University (www.geo.uu.se), Uppsala, 2019 Content 1 Introduction ---------------------------------------------------------------------------------------------1 2 Background ---------------------------------------------------------------------------------------------4 2.1 Definitions and Assumptions --------------------------------------------------------------------------4 2.1.1 Pollinators-------------------------------------------------------------------------------------------------4 2.1.2 Living Walls----------------------------------------------------------------------------------------------4 2.2 Background Literature ----------------------------------------------------------------------------------5 2.2.1 Pollinator Habitat Requirements ----------------------------------------------------------------------5 2.2.2 Plant Requirements on Living Walls----------------------------------------------------------------- 6 3 Methods --------------------------------------------------------------------------------------------------7 4 Results ----------------------------------------------------------------------------------------------------9 4.1 Literature Review----------------------------------------------------------------------------------------9 4.1.1 Plants Available on Living Walls and Potential Habitats------------------------------------------ 9 4.1.2 Favourable Plants and Habitat for Pollinators ------------------------------------------------------10 4.2 Survey Results-------------------------------------------------------------------------------------------15 4.2.1 Survey response -----------------------------------------------------------------------------------------15 4.2.2 Nesting Sites-------------------------------------------------------------------------------------------- 15 4.2.3 Nutrients, water and soil------------------------------------------------------------------------------ 18 4.2.4 Soil Type------------------------------------------------------------------------------------------------ 19 4.2.5 pH Range------------------------------------------------------------------------------------------------ 22 4.2.6 Plant heights-------------------------------------------------------------------------------------------- 23 4.2.7 Plant diversity ------------------------------------------------------------------------------------------24 4.2.8 RHS perfect for pollinator’s logo-------------------------------------------------------------------- 27 5 Discussion ----------------------------------------------------------------------------------------------28 5.1 Reconstructing Habitat in Practice ------------------------------------------------------------------30 5.2 Other Benefits-------------------------------------------------------------------------------------------32 5.3 Are they Sustainable? ---------------------------------------------------------------------------------33 6 Conclusion ---------------------------------------------------------------------------------------------34 7 Acknowledgements -----------------------------------------------------------------------------------35 8 References ----------------------------------------------------------------------------------------------35 9 Appendix -----------------------------------------------------------------------------------------------40 9.1 Living Wall Questionnaire----------------------------------------------------------------------------40 9.2 Plant recommendations -------------------------------------------------------------------------------42 The Potential of Living Walls to Host Pollinator Habitat SHIRIN EL GHOMARI El Ghomari, S., 2019: The Potential of Living Walls to Host Pollinator Habitat. Master thesis in Sustainable Development at Uppsala University, No. 2019/39, 62 pp, 15 ECTS/hp. Abstract: Pollinator biodiversity and abundance is an ecosystem service vital for humans, provisioning a range of essential goods including food, fibre and medicines. Despite this, pollinators are under threat and are experiencing global declines. Habitat loss is a driving force behind such declines and, as such, the potential to provision more pollinator habitat is of interest. Currently, urban areas host abundant unused space in the forms of roofs and walls, which could be utilized to provision some pollinators with additional forage, and possibly nesting sites, without compromising human use of the land. While several studies exist regarding the habitat potential of living roofs, the impact of living walls on biodiversity is little studied. This paper sets out a theoretical approach on whether living walls could be used to host pollinator habitat by surveying living wall manufacturers regarding the physical properties of the living wall systems they use and their plant choice. Keywords: Sustainable development, biodiversity, pollinators, living walls, urban greening. Shirin El Ghomari, Department of Earth Sciences, Uppsala University, Villavägen 16, SE- 752 36 Uppsala, Sweden The Potential of Living Walls to Host Pollinator Habitat SHIRIN EL GHOMARI El Ghomari, S., 2019: The Potential of Living Walls to Host Pollinator Habitat. Master thesis in Sustainable Development at Uppsala University, No. 2019/39, 62 pp, 15 ECTS/hp. Summary: Pollinators are vital for human wellbeing and survival, being essential for the continued propagation of most plants, which in turn provide a range of essential goods such as food and medicines. Pollinators are, however, globally declining. Habitat loss due to factors such as agriculture, urbanization and climate change are driving forces behind such declines and there is a growing need to provision pollinators with more habitat to forage and nest. As countryside becomes increasingly degraded, urban landscapes are becoming important for wildlife. Currently, many bare walls and roofs exist in cities offering space that’s largely unutilized. Much of this space has potential to support plant life that could provide foraging opportunities to help support pollinators while not disturbing human land use. Nevertheless, the potential of greened walls to benefit biodiversity is little studied. This paper therefore seeks to investigate whether living walls, a type of green wall, could provide pollinator habitat by surveying living wall manufacturers regarding the features of their living wall systems and the plants they recommend. Keywords: Sustainable development, biodiversity, pollinators, living walls, urban greening. Shirin El Ghomari, Department of Earth Sciences, Uppsala University, Villavägen 16, SE- 752 36 Uppsala, Sweden 1. Introduction Healthy biodiversity contributes to a range of ecosystem services. Among these is pollination which provides humans with multiple benefits including food, plant-based medicines, fibre, genetic diversity and improved ecosystem resilience (Bauer & Wing 2016, Potts et al. 2010). It’s estimated that animals pollinate 90% of all plant species (Evans et al. 2018, Menz et al. 2011), and among these pollinators, insects, and particularly bees, are the most prevalent. By volume, pollinators contribute to 35% of global food, but by species, 75% of cultivated plants require animals for their reproduction. These species include many forage and vegetable crops and the majority of fruits and seeds (Nicholls & Altieri 2013, Potts et al. 2010, Steffan-Dewenter et al. 2005), which are important nutritional sources for humans. As such, pollinators are important to a country’s food security and economy (Breeze et al. 2012) and globally this ecosystem service is worth more than $100 billion annually (Nicholson & Ricketts 2019). The value of pollinator biodiversity to agriculture can be underestimated, however. It’s been suggested that a few generalist pollinators could maintain pollination services (Steffan-Dewenter et al. 2005) with the generalist European honey bee, Apis mellifera, often credited as agriculture’s most valuable pollinator (Evans et al. 2018, Bortolotti et al. 2016). However, while honeybees can pollinate most crops (Breeze et al. 2012), generalised crops, specialized crops, and even self-compatible plants, have all been shown to benefit from increased pollinator biodiversity (Steffan-Dewenter et al. 2005). Many wild pollinators, including solitary bees, bumblebees, wasps and flies, appear equally as important as honey bees. Furthermore, wild pollinators pollinate some crops, such as orchard fruits and oil-seed rape, more effectively (Evans et al. 2018). Mason bees, for example, are the most effective pollinators for apples, long tongued bees are needed for field beans, and for some crops, including strawberries, managed and wild bees are both required to produce market quality fruit. In some cases, honeybees cannot pollinate the crop at all, such as in tomatoes where large bodied bumblebees are needed to vibrate flowers for pollen release, a task honeybees are ineffective at performing (Breeze et al. 2012). Financial