Role of Urban Green Spaces for Cities under Climate Change Aspects of Planning and Implementation. Juliane Mathey, Stefanie Rößler, Wolfgang Wende

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1 Role of Urban Green Spaces for Cities under Climate Change Aspects of Planning and Implementation Juliane Mathey, Stefanie Rößler, Wolfgang Wende

2 Background Urban heat island: urban areas suffer from special climate conditions (dryness, heat, less wind compared to the rural surrounding) Climate change: conditions will be strengthened Influence the quality of life (heatwaves, heatdepending health problems) Urban Green Spaces: supply ecosystem services, climate regulation Urban heat island + climate change Impacts / Risks: changes of species compositon, vegetation structure Adaptation: potentials to regulate urban climate Mitigation: carbon sink, reducing cooling energy Urban Green Spaces

3 Urban Green Spaces and Climate Change Yet warmer and dryer? Urban nature and green space development under climate change Federal Ministry for the Environment, Nature Conservation and Nuclear Safety Team of IOER and TU Dresden, chair for meteorology 10/ /2010

4 Research Questions and Approach How do urban green spaces (UGS) contribute to urban adaptation strategies on the impacts of climate change? How the implementation of green space planning can be improved in urban development? Analysis of urban (green) structure (IOER) + Climate modelling (TUD) Analysis of urban green space planning and development (IOER) Climatic regulation effects of UGS: potentials, future relevance, limits Potentials and deficits of planning strategies and instruments Recommendations for urban planning + general adaptation strategies for planning and management of UGS

5 Structure Analysis Correlations between urban vegetation structures and micro climate conditions Basis: Mapping of urban biotope types Identification of homogeneous units according vegetation structure 57 Urban Vegetation Structure Typs Characteristics of vegetation inventory: proportion of green, green volume, sealing, built-up area, height of buildings, connection Basis for modelling climatic regulation effects for single units of urban vegetation for the whole green system of a city

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7 Climate Modelling (HIRVAC-2D) City Level: All Urban Vegetation Structure Types of a City Modelling of the maximum cooling effects of the UVSTs of a city Cooling effects are especially high in big parks or wood areas. Analysis of the climatic regulation effects of the green system of the whole city Planning Recommendations Maximum cooling effects *[ t max in K] in 1,5 m height, related to a dry sealed surface. Database: Juliane IOER; Mathey, HIRVAC-2D UNECE Prague simulations: 4 th May 2010 TU Dresden *difference of the daily maximum of the air temperature in height 1,5 m on a summer day

8 Green is not equal to green! Green spaces have positive effects on urban climate. There are (small-scale) differences according to the cooling effects within green spaces depending on vegetation structure types. Big and coherent areas have a stronger cooling effect compared to small areas. The higher the green volume density of a green space, the stronger is the cooling effect. Cooling effects of UVST are in nights different from days. Built-up areas have almost no cooling effect.

9 Densely build-up quarters heat up very much in summer. During days climatic effect of dry lawns are like effects of sealed areas. Greened walls have effects for climate regulation. Shadows of trees in parks are loved places on hot summer days.

10 Table of of Characteristics for Urban for all Vegetations 57 Urban Structure Vegetations Types Structure Types 1.2 Built-up Area with Richly Structured Garden Anteil an der Stadtfläche: hoch Structure of Vegetation Merkmale durchschnittlicher bis hoher, z. T. alter Laubgehölzanteil (teilweise Kronenschluss) jüngere Laubgehölze und Koniferen sowie Zierrasenflächen; einfache Struktur Vegetationsflächen Vegetations -schichtung Land Use / Built-up Structure Wohnbauflächen Einzel- und Reihenhausbebauung; Flächenanteil: extrem hoch, Blockrand- und Zeilenbebauung; Flächenanteil: mittel viel- und mehrgeschossige Wohnbebauung; Flächenanteil: sehr gering Flächen öffentlicher u. halböffentlicher Einrichtungen; Flächenanteil: gering Gewerbeflächen; Flächenanteil: gering Industrieflächen; Flächenanteil: sehr gering Kenngrößen: Versiegelungsgrad: 38 % ; Überbauungsgrad: 20 % Climate Effects Grünflächenanteile (Draufsicht) [%] niedrig 40 0,20 mittel 8 0,12 hoch 23 2,20 Gesamt 71 2,52 Spez. Grünvolumen Table [m³/m²] of Characteristics for Urban Vegetations Structure Types Structure of Vegetation Land Use / Built-up Structure Climatic Regulation Effects Biodiversity Biodiversity Temperaturverhalten auf der Fläche Luftaustauschpotenzial auf der Fläche Tag sehr geringe Abnahme deutlich Randwirkungen auf Nachbarflächen deutlich Nacht deutliche Abnahme deutlich deutlich -Biotopvielfalt: reich strukturiert bis strukturarm -Hemerobie: stadttypische Biotope bis naturnahe Biotope -Regenerierbarkeit: schnell regenerierbar bis langsam regenerierbar -Sonderstandort -Lebensraum (Habitat) für spezifische Arten -Gefährdungsrisiko durch den Klimawandel (Grad eines drohenden Biodiversitätsverlusts)

11 Scenario for Land Use Change Quarter Park with Lawn Building-up a lawn of a quarter park Build-up Area on the Lawn 0,5 K to 1,0 K higher temperature than before Modelling of climatic behaviour (HIRVAC-2D) Aim: demonstrating the microclimatic effects caused by planning decisions and projects

12 Adaptation by urban green spaces? Influenced by: Urban structure, green space system Characteristics of green spaces (size, vegetation structure, surrounding) Maintenance and management of green spaces Use (accessibility, time of use, functions) Potentials and limits of the climatic effects (cooling) by urban green spaces Synergies and conflicts of aims Distinguished planning approach

13 Synergies and Conflicts Mitigation Adaptation: Carbon (CO 2 ) reduction by compact urban areas versus green systems Urban vegetation as carbon sink Relation to other aims: Aim to avoid urban sprawl : reuse of urban wastelands by building-up versus development of urban green systems Biodiversity (inner-city ecosystems versus protection of natural areas)

14 Adaption by Planning & Measures Regionalplan Oberes Elbtal/ Osterzgebirge 2009 Regional Level cold and fresh air flow - areas for development - lanes for air flow city-regional green space systems City Level Flächennutzungsplan 2010, Stuttgart different urban green space types (UVST) - place - connection - dimensions urban green space system Bebauungsplan Nr. 345, LH Dresden Local Level design of single urban vegetation structure types (UVST) - structure of vegetation - use - maintenance concrete areas

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