Ecosystem Services of Urban Green at Public Squares in Munich

Background and issues

Public squares are a central design element of a city and of great importance for the living quality in the city. Their design regar­ding sealing grade, buildings and infra­structure and moreover vege­tation can vary tremen­dously. In many cases, public squares are heavily frequen­ted areas within the city center and have often very different effects on the individual and thermal well­being of humans due to their diverse structural ele­ments.

The design of public open spaces is in the context of the urban heat island effect and the conse­quences of climate change a central issue of city plan­ning. Especially public squares should be designed attrac­tive for humans and more­over foster the thermal well­being of humans. For this, urban green can contri­bute by provision of so called eco­system services such as shading, cooling, humidi­fication, wind buffer­ing, promotion of bio­diversity and aesthetic.

At this point of green space planning and research works the project "Eco­system Services of Urban Green at Public Squares in Munich". The project will record the available urban green at selected squares in Munich and quantify their eco­system services. For this, two different modell­ing approa­ches will be used on the one hand to calculate the regulative services by carbon storage, cooling effects and shading (with the process-­based growth model CityTree, see project "City Trees II") and on the other hand analyse the effect of vege­tation on the thermal well­being of humans in high temporal resolution (high resolution climate model ENVI-­met, see project "Urban Green Infrastructures"). Moreover, at chosen days (hot days, cool days) the services of vege­tation will be measured exemplarily as well as different design scenarios will be tested in view of climate change. With these approaches, recom­mendations for a future sustainable and efficient design of built-up areas and urban green at public squares can be provided.

Objectives

The planning and design of public squares, especially of urban green, is so far mostly follo­wing aesthetic basics and less the expected services provided by vege­tation. However climate change poses severe problems, the thermal comfort of humans is often in­adequate at heavily sealed with dense built-­up areas and heavily frequen­ted squares and can lead to signifi­cant health problems.

Climate scenarios predict a decrease of the living quality in cities due to more hot days and warm periods as well as changed preci­pi­tation patterns. A change in the design of public squares to higher thermal comfort is there­fore nece­ssary for a climate adapted city of the future. In this inter­disci­plinary project the services of present urban vege­tation at chosen squares in Munich for recent climate para­meters will be compiled and the effect on the thermal comfort of humans will be shown. More­over, with climate models and several different design scenarios, future possi­­bili­ties for the design of public squares in view of climate adap­tation will be developed. These findings will be assessed within the context of the eco­system services of vege­tation, the thermal comfort of humans as well as the aesthetic of the squares.

With two modelling approaches, the services of urban green infra­structures under current climate condi­tions and built-­up areas (especially the sealing degree) as well as the effects of changes for climate and structural elements of the squares simulated. In a further model­ling approach it will be tested, how different design scenarios affect the thermal comfort of humans at the squares to gain know­ledge for future space design. These findings will be tested at selected days (hot days, cold days, cloudy days) and for different squares and green infra­structures. Finally the results will be combined with the results of the project Places:M to further consider the feelings of humans.

Based on these knowledge gaps the project will assess the following objectives:

  • Q: Which contributions are performed by green (trees, hedges, grass) at public squares in Munich for the cool­ing of air temper­ature, the de­crease of rain­water run­off and the carbon storage in relation to plan­tation clusters (trees - hedges, dense foliated - sparse foliated, young trees - old trees)?
  • Q2: How to the eco­system services of vege­tation (trees, hedges, grass) of an public square in Munich change under changed climate condi­tions (in­crease in temper­ature, changed preci­pitation patterns)?
  • Q3: How can the selected squares be adapted to climate change (cooling by transpiration, de­crease of run­off, in­crease of carbon storage), e.g. by different tree species, planting density, etc.?
  • Q4: How are the climatic conditions of selected squares on single days? Can opti­mizations of the site climate conducted by vege­tation (trees, hedged, grass)?

Methods

All analysis to answer the objectives of the project will be conducted at selected squares of the ZSK sub­project "100Places:M" in Munich. Out of the total number of squares will be 20 squares selected, which are represen­tative for different square types concer­ning loca­tion within the city, geo­metry and usage as well as plan­ting types. The selec­tion will be based on the data­base of the project 100Places:M about the analysed squares in Munich and in close co­operation with the re­searchers of 100Places:M. Time-­intensive measure­ments such as the model­ling of squares with ENVI-­met will likely be conduc­ted on a part of the selected squares (up to 10 squares), which will also be represen­tative for Munich regarding their features, geo­metry and loca­tion.