ENHANCING URBAN BLUE AND GREEN SPACES
Introduction and Background As the climate crisis continues, the demand for carbon neutrality is increasing. The current economy is still heavily dependent on fossil fuel energy. And thus, a nature-based solution such as increased carbon sequestration is an attractive method to ultimately lower CO2 concentration in the atmosphere. Oftentimes, offsetting of carbon is done outside of urban areas, in distant places. However, such compensation projects seem to neglect the advantages that local natural areas may have on people's well-being [1]. Worldwide the urban areas are rapidly expanding [2], and this pattern is visible in Lund where the demand for housing is increasing [3]. In this context, nature based solutions, an approach in which nature is rebuilt to offer benefits in climate mitigation, needs to be integrated in the climate
change mitigation agenda [4]. There is a window of opportunity. The city of Lund has committed to carbon neutrality by 2030 opening the possibility for nature-based solutions to be integrated into planning. Innovative new initiatives can not only improve carbon uptake, but create wider benefits for the local community and well-being of inhabitants. Urban water bodies and wetlands specifically are very efficient in taking up carbon while having a range of other benefits [5]. This policy brief presents the idea behind ’Project Pond’, discussing the benefits of improving urban blue/green spaces in the hopes of increasing carbon sequestration through an improved pond shoreline design.
Biodiversity and its Benefits Small ponds can host a range of different habitat types. This diversity is vital to ecosystem health and services as it can support a broad range of species which contributes to the landscape-level biodiversity more than homogeneous areas, fostering habitat equilibrium [6]. Fauna is strongly linked to the presence of flora. Thus, the design and construction characteristics of urban ponds are important in fostering the ability to serve as biodiversity hotspot [7]. Balancing the size of the 3 habitat zones (terrestrial, semi-aquatic, aquatic) is dependent on the structure of the pond[8]. What is needed is a nature-like design of well-vegetated ponds, a high diversity of different pond types and particularly a
redesign of existing urban blue/green spaces to include more nature-like features in order to support habitat equilibrium [9]. Carbon cycling, carbon sequestration, and biodiversity support services should not be seen as separate goals. Rather, they are interlinked and can enhance one another. Furthermore, improved natural urban areas may enhance connectivity of these spaces. Improved connectivity of habitats means increasing the communication and interaction of specific organisms, and when talking about water bodies, this connectivity provides other benefits such as water purification, pollution control and habitat restoration [10].
Box 1. Ecosystem services of urban ponds In urban areas, the need for water bodies with technical functions- regulating services (i.e. stormwater retention ponds) had led to the decrease of natural ponds. Besides the technical benefits, ponds provide a variety of different ecosystem services, which in simple terms, are the benefits that society and the environment obtains from a particular ecosystem[11]. Amongst the most important ecosystem services to mention are illustrated in figure x. Based on scientific research, urban ponds take up more carbon and
support a broader range of biodiversity compared to other urban green spaces (parks, playgrounds) [12]. The concept of pond improvement as explained throughout this brief, is built upon the link between carbon sequestration, biodiversity, and natural water cycling and mixing. The latter two are natural processes that can be enhanced by a variety of plants and animals in and around the pond. Promoting biodiversity improves the quality of air, water, and soil, providing citizens with a clean and beautiful environment [13].
INTERVENTION
ECOSYSTEM SERVICES
Habitat for biodiversity
Pond improvement
Air, soil, water quality regulation Carbon sequestration and storage Recreation and culture
FIGURE 2
SOCIO-ENVIRONMENTAL BENEFITS
Environmentally friendly areas Carbon neutrality Physical and mental health
‘Project Pond’: Design, Littoral Zone and Native Flora Pond design consists of three different levels: the aquatic, the semi-aquatic, and the terrestrial. The right balance of these three habitats can make for a beautiful pond that flourishes with different species of plants and the animals that these plants attract. Although the balance is important, it is mainly the semi-aquatic (or littoral zone) that holds the greatest variety of biodiversity [14]. This is because the semi-aquatic zone offers the greatest breadth of habitats; water and soil interact together to create a dynamic space in which multiple species can coexist. The animals that are attracted by these plants contribute to the health of the selection of vegetation and the ability of plants to continue sequestering carbon [14]. Therefore it is vital
Box2. Flora Figure 3 illustrates specific native plants which have the best vegetative features for biodiversity support and carbon uptake due to their functions. Most of the selected plants flower in different months of the summer thus attracting a high diversity of pollinators (3, 4, 5, 8, 10). Additionally, chosen vegetation attracts a variety of small animals by shedding seeds around early Autumn which can be eaten by birds, squirrels and other small mammals (6, 7). Some plants are also useful by providing them with shelter (1, 2, 9). Most importantly, some plants (5, 7) are essential for a specific species of insects such as larvae of Plusia festucae which can only live and feed on a few certain plants. The majority of selected plants have high biomass, wide rhizomes (underground stems), large
for ponds to have a gentle slope and littoral shelves rich in species to be able to serve us with the aforementioned benefits [15]. Other characteristics important to consider are the distance between ponds to the nearest buildings or roads, how busy this area is, and the amount of floating vegetation. It was found that close proximity to high-traffic areas can decrease the amount of species present [16]. Furthermore, aquatic vegetation can increase biodiversity as it offers more diverse habitats, but only to a limited extent. In particular floating vegetation tends to spread quickly and this tends to result in a smothered pond if not well-maintained [17]. Therefore most floating flora was left out of our pond design guide.
root systems and are quite fast growing. This influences the quick acclimatisation and absorption of high amounts of organic and inorganic pollutants [18, 19]. These particular factors allow the plants to act as great carbon sinks. For example Betula Pubescens works as a great carbon sink as “the average of carbon concentration in the trees was approximately 50%” [20]. Collaborating along with the Botanical Garden in Lund we selected native species of plants for all the different zones of the shoreline. Moreover, in order to reduce the maintenance of the ponds, the suggested vegetation requires the minimum effort and it is easily adaptive. It should be noted that there are numerous possible combinations of species of plants. The vegetation is not limited to the species portrayed in the illustration.
Conclusions and Further Steps The reality we face today is that climate neutrality is far from our reach if we focus only on the pollution sources. We all realise that we are way past the point when the idea of emissions reduction is enough on its own. We need to actively create more and better quality carbon sinks that bring with them multiple benefits not only carbon uptake. This policy brief is a short summary of an extensive scientific literature that underlines the benefits of urban green and blue spaces which lead to the proposed urban pond design guidelines. In the context of the climate crisis and rapid urbanization, decision-makers need to acknowledge and enhance the capacities of these spaces by supporting nature-based solutions which can help in addressing the environmental problems we face today. Cities need innovative and ambitious leaders that strive towards creating the best environment for the inhabitants and motivated decision-makers that take the best opportunities to make a change. This change can start with 3 simple initial steps: 1 - Acknowledgement of the complexity of managing blue/green spaces. 2 - Embracing interdisciplinary collaborations that are needed to address the complexity. 3 - Getting blue/green spaces higher on the agenda as they hold so much potential! The design approach suggested here is not the only way forward. ‘Project Pond’ team hopes this document will encourage the discussion and is open to possible future collaborations. The ultimate aim is to maximize the value and function of urban green and blue spaces, benefiting humans and the environment altogether.
Project Team Environmental Studies & Sustainability Science Master students (LUCSUS), class of 2021. ‘Project Pond’ was born due to an assignment when we decided to start research the potential of CO2 sequestration in urban areas. We look forward to continue our journey and research on this topic. Monica Sturza BA International Relations & European Studies Olivera Stojilovic BSc Marine & Environmental Science Ruta Lukosiunaite BA Architectural Technology & Construction Management Simona Jastremskaite BA Translation and Editing Suzanne Oostdam BA Environmental Science & Human Geography
Contact email: projectpond.lund@gmail.com Acknowledgments We would like to thank the Botanical Garden in Lund, the Center for Environmental Research, Va Syd, LUCSUS and Lunds Kommun for sharing their knowledge and agreeing to collaborate with us on this project. REFERENCES: [1]Nordström, J. (2012). Förskolors och skolors nyttjande av grönområden.[Preschools and schools' use of green spaces][2]United Nations, Department of Economic and Social Affairs, Population Division (2019). World Urbanization Prospects: The 2018 Revision (ST/ESA/SER.A/420). New York: United Nations.[3]New comprehensive plan - Lunds kommun. Lund.se. (2020). Retrieved 23 March 2020, from https://www.lund.se/en/transport--spatial-planning/new-comprehensive-plan/.[4]Goertzen, D., & Suhling, F. (2013). Promoting dragonfly diversity in cities: major determinants and implications for urban pond design. Journal of Insect Conservation, 17(2), 399-409.[5]Holgerson, M. A., & Raymond, P. A. (2016). Large contribution to inland water CO 2 and CH 4 emissions from very small ponds. Nature Geoscience, 9(3), 222. [6]Hassall, C. (2014). The ecology and biodiversity of urban ponds. Wiley Interdisciplinary Reviews: Water, 1(2), 187-206. [7]Hassall, C., & Anderson, S. (2015). Stormwater ponds can contain comparable biodiversity to unmanaged wetlands in urban areas. Hydrobiologia, 745(1), 137-149.[8] Holtmann, L., Kerler, K., Wolfgart, L., Schmidt, C., & Fartmann, T. (2019). Habitat heterogeneity determines plant species richness in urban stormwater ponds. Ecological Engineering, 434-443.[9]Goertzen, D., & Suhling, F. (2013). Promoting dragonfly diversity in cities: major determinants and implications for urban pond design. Journal of Insect Conservation, 17(2), 399-409.[10]Li, Y. C., Wu, H. N., & Wang, J. W. (2011, September). Adaptive neural boundary control design for a class of nonlinear spatially distributed systems. In 2011 IEEE 5th International Conference on Cybernetics and Intelligent Systems (CIS) (pp. 386-391). IEEE.[11]Hassall, C., & Anderson, S. (2015). Stormwater ponds can contain comparable biodiversity to unmanaged wetlands in urban areas. Hydrobiologia, 745(1), 137-149.[12]Holgerson, M. A., & Raymond, P. A. (2016). Large contribution to inland water CO 2 and CH 4 emissions from very small ponds. Nature Geoscience, 9(3), 222.[13]Lundy, L., & Wade, R. (2011). Integrating sciences to sustain urban ecosystem services. Progress in Physical Geography, 35(5), 653-669.[14] Kavehei, E., Jenkins, G. A., Adame, M. F., & Lemckert, C. (2018). Carbon sequestration potential for mitigating the carbon footprint of green stormwater infrastructure. Renewable and Sustainable Energy Reviews, 1179-1191.[15] Holtmann, L., Kerler, K., Wolfgart, L., Schmidt, C., & Fartmann, T. (2019). Habitat heterogeneity determines plant species richness in urban stormwater ponds. Ecological Engineering, 434-443.[16] Goertzen, D., & Suhling, F. (2013). Promoting dragonfly diversity in cities: major determinants and implications for urban pond design. Journal of Insect Conservation, 17(2), 399-409.[17] Blicharska, M., Andersson, J., Bergsten, J., Bjelke, U., Hilding-Rydevik, T., & Johansson, F. (2016). Effects of management intensity, function and vegetation on the biodiversity in urban ponds. Urban Forestry & Urban Greening, 20, 103-112.[18] Saxena, G., Bharagava, R. N. (2019). Bioremediation of Industrial Waste for Environmental Safety. PRINT[19] Temperton, Vicky & Grayston, Sue & Jackson, G & Barton, Craig & Millard, Peter & Jarvis, P. (2003). Effects of elevated carbon dioxide concentration on growth and nitrogen fixation in Alnus glutinosa in a long-term field experiment. Tree physiology. 23. 1051-9. 10.1093/treephys/23.15.1051.[20]Uri, V., Varik, M., Aosaar, J., Kanal, A., Kukumägi M., Lõhmus, K. (2011). Biomass production and carbon sequestration in a fertile silver birch (Betula pendula Roth) forest chronosequence. Forest Ecology and Management, 267, 1 March 2012, Pages 117-126.