Data collecting

The case study of the multifunctionality in Greenbelt Frankfurt have two main analyzing process, the semi-quantitative mapping and qualitative coding. The first part of mapping focuses on the visualization of the spatial distribution of each ES and general performance of Greenbelt;

the second part of coding focuses on the reorganization of existing main planning documents into the same framework.

The first part of the case study is to produce the spatial distribution of ES capacities in the studied area. In this process, the main applied methodology is A semi-quantitative land use based GIS mapping which was first proposed and used by Burkhard, and later others (Burkhard, Kroll et al. 2012, Koschke, Fuerst et al. 2012, Lovell and Taylor 2013, Kopperoinen, Itkonen et al. 2014).

The core concept lies in the grading matrix for each kind of land use on their general performance according to related experts. Comparing with other pure quantitative approaches, it is more convenient for non-ecologists and directly gets closer connection with land use and land cover, the critical object in urban planning. But it could also be too general and lack local information. A later case who mainly used local policy related data, like natural reserves and protection zones, give more particularity in the case but hard to apply on different cases without equal information (Kopperoinen, Itkonen et al. 2014). Both these approaches were used on regional/watershed scale and have better inspiration for regional planning strategies.

In this study, as described in the methodology chapter, a combined approach is used here to take advantages of both. First of all, the land use data is graded as the former approach, but with urban policy-related information as added on data to keep both tangible and intangible data of the studied area. Second, more detailed data sources are used. Most former works used the CORINE

on the regional scale. CORINE land cover is strong in its wide coverage and unified standard due to its initiated organization, the European Union; in the meantime, the in total 44 classes of land cover and the scale of 1:100 000 indicates that it could be insufficient for urban green space which are in the classification oversimplified. In this way, the 1:2000 Biotope Map of Frankfurt was applied in the study, as well as some additional information was add to different type of ES based on city-wide policy and special plans. In this way, the Biotope Map of the studied area is the critical data for ES mapping of year 2010.

1) The Biotope Type Map of Greenbelt

The Botany Department of Senckenberg Research Institute started the extensive mapping of the biotope types throughout the Frankfurt city since 1985, under the commission from the city council. One main focused research location of the Senckenberg Research Institute is the metropolitan area of Frankfurt and the flora and fauna of the region have been documented in the collections of the Senckenberg association for nature research (Senckenberg Gesellschaft für Naturforschung, SGN) for nearly 200 years. The working group of the Biotope Map is led by Dipl.

Dirk Bönsel from the beginning. The filed surveys normally involved a group of master students but the organization work was done by the three group members who are all researchers of the institution. It was a small group and shorthanded for the survey area, however, a unified standard can be better followed within the group.

The map is not stable but under constant revising. The first version of Frankfurt Biotope Type Map finished in 1990. At that time, the main focus was the urban area, with exceptions in the nature reserves, the urban forest and large industrial facilities. Since then, revision maps have been carried out every five years to correct changings and complement the gaps. In the mapping section 2001-2005, an indicative instruction handbook which originated in 1997 was more formerly and strictly developed based on many related biotope mapping studies, and the whole map was digitalized by the City Surveying Office (Stadtvermessungsamt) simultaneously. The digital map was available within the intranet of the municipal authorities and is functioned as a main database for related urban works (Bönsel 2007).

The 4^th revision mapping (2005-2010) restricted to the non-developed area and the Greenbelt.

And the latest version (2010-2015) has focused on the main changes along the Nidda river. This version (data recorded until 2014) is used as base map of the ES spatial distribution in 2010s.

According to the distribution of time dated (Fig 5.2.1), the majority of the data is dated between 2007 to 2012, thus could serve the purpose well.

Fig 5.2. 1 The spatial distribution of revising year of the Biotope Map in studied area, draw by author, origin map from Department of Environment, Frankfurt.

The biotope mapping is demarcated on the aerial image and also with the help of the 1:2000 urban ground map, and carried out in the field for surveying. Then the biotope map is drawn in a 1:2000 scale and other data, including name, date, type and additional information, are recorded in the excel and digitalized with the graphic information to form the database. The minimum area size for the mapping is defined as 5m * 5m. The classification system of biotope types is a hierarchical structure which allows the space to be captured in a detailed sharpness. The biotope types used generally three levels, the Main Group, the Subgroup and the Main unit. A fourth level, the Subunit, is also applied since it is quite meaningful for further differentiate for example the degree of sealing and utilization. This fourth level has each a more detailed explanation made with indications on characteristic plant societies and species. In order to achieve as detailed results as possible, the mapping is carried out at lowest present level and normally at least until the third level, the Main Unit. If an encountered habitat type can not be assigned to a Subunit, the next higher level would be used. Besides these types, some additional information is added like the nature reserves Flora-Fauna Habitat (FFH in short) (Bönsel 2007).

This biotope map is valuable not only for the institution but also for many other related studies of the area. Since the founding of the working group in 1985, more other detailed flora-fauna investigations have been carried out in selected areas of Frankfurt known as “specific mappings”. These helps to the complex topics such as landscape facilities, species inventory, nature conservation, and also in some independent and comprehensive projects like Frankfurt 21, the Urban Forest and Airport project. After the extensive digitalization and update of mapping procedure based on newest progress in 2005, the Biotope Map could better catch the current

requirement in a wide range and provide much more information beside the map. The case study here only uses the very preliminary level of the database.

2) Historical land use map

To understand how multifunctionality in the study area have changed in a certain time period, the searching for how it was before could be necessary. However, there are no digital land use data for the 1990s. The most comparable map for the newest Biotope Map of 2010s would be the first version Biotope Map finished in 1990. But this map has not been digitalized yet due to the staff shortage of the group. Though the paper version is well kept in documentation, the amount of work is not possible to be done by author alone. On tracking with urban land use data, two paper historical maps were available from the Frankfurt Institution of City History, the Land Use Plan of 1988 in scale 1: 50 000, and the Land Use Plan of 1984 in scale 1: 25 000. But these two also have disadvantages that they are made mainly for built areas and the land use type inside Greenbelt were quite simple.

Shifting the thinking of a complete comparison, preliminary and approximate location of changes seems to be a reasonable approach. The comparison is taken between the changes on the Greenbelt Leisure Map 1992 and 2011, the first and latest version of the map. This pair of maps have three advantages for the case study. First of all, the two maps both focused on Greenbelt and other open space in the city, instead of the built area. The aim of the map is to provide citizens with available possibilities in open spaces, with necessary public transportation and road information, the buildings in the city are just a background. Second, the maps have same content. Open spaces inside and outside Greenbelt were classified as forest, public green spaces and parks, cemetery, small gardens, sport areas, grassland and agricultural land (public open space and cemetery were merged as one type in 1992 map). It is more detailed than that in urban land use types and directly comparable with the Main Group of the classification of Biotope Map, which means the same evaluation standard. Last but not least, the timing of maps fits the study purpose. The Leisure Map 1992 was made during the transitional working group of Greenbelt and the beginning of the Greenbelt GmbH, when the range of the belt was settled but no substantial works done. This map served as a status quo for the beginning of Greenbelt, while the 2011 Leisure Map were filled with destinations, route and lines, facilities as well as new landscapes. They most closely captured the changes of the area.

These two maps were drawn both in scale of 1: 20 000, which is much smaller than the Biotope Map. So the maps were compared under the same range but only the different parts are marked and digitalized, then import into GIS with same coordinate and range. In this way, these less accurate changes will be mapped and present to show the main differences in the two decades.

In second part of the case study, the efforts from the planning process are discussed, with same focused ES. This involved planning documents and policies since 1990. The process is divided into three steps, the first is the Greenbelt planning in 1991 which involved the documents from the Greenbelt Project Year 1990 and the documents of the Greenbelt Constitution in 1991.

The second part is the gradual implementation process, mainly focused on the Project Group since 1997, including documents like project planning, open information, experts’ reports and investigation from third company. In the last part, the planning documents, the analyzing report and recent pilot projects are used to identify the main purposes and actions after 2010s.