Vegetation Heights 2020

Introduction

There are several Environmental Atlas topics that detail Berlin’s urban development and its effects both on the residential structure and the distribution and use of non-built-up areas:

• “Actual Use of Built-up Areas” (06.01),
• “Inventory of Green and Open Spaces” (06.02),
• “Urban Structure” (06.07).

In addition to this information, the maps on “Urban Structural Density” (06.09) explore the degree of structural use.

These individual separate findings, however, only provide limited insight into the vertical extent of the natural structures in the city. For this reason, the Environmental Atlas presents the height development of buildings (Map “Building Heights” (06.10.1)) and that of vegetation (Map “Vegetation Heights” (06.10.2)) in two topics. The first joint “Building and Vegetation Heights” map (06.10) was produced in 2010, as part of a project with the Institute of Optical Sensor Systems of the German Aerospace Center (DLR). Today, an official, regularly updated 3D building model is available for Berlin’s building stock, forming the basis for the “Building Heights” map (06.10.1). The “Vegetation Heights” (06.10.2) map that complements the “Building Heights” map, however, is still based on the Environment Atlas’ own analysis of aerial photography data obtained during summer flights of the respective years.

Regarding Berlin’s tree stock, a dataset that is based on the tree register of the Berlin Green-Space Information System (GRIS) is available. It includes roadside trees as well as trees growing in public green spaces and recreational areas (cf. Figure 1). However, this dataset does not include any trees in forest areas and on private land (incl. the green spaces managed by Berlin’s housing associations). Therefore, a large part of the ‘urban greenery’ is actually not mapped. A city-wide analysis of remote sensing data is required to capture the ‘urban greenery’ in its entirety from above.

Fig. 1: Section of Berlin’s tree stock, Preußenpark Wilmersdorf area, background: map of Berlin 1 : 5,000

Precise and detailed information on the height and structure of vegetation areas may be important for many different use cases. The purpose of such a data base may be to provide information

• for a more precise modelling of the urban climate,
• for a more nuanced differentiation of use mappings regarding biotopes and green spaces, and
• to form a basis for deriving indicators, including the green volume number or parameters for the vegetation’s capacity to form carbon.

The accuracy of each model strongly depends on the quality of the input data. For example, to enable a detailed calculation of the course of air channels and ventilation conditions, accurate information on the aerodynamic surface roughness, including its geometric dimensions, has to be available. Elevated objects, such as buildings or entire blocks of buildings, as well as high and dense tree structures present obstacles. They may have a wind-breaking effect or eliminate wind completely; or else these obstacles may have a channelling effect, accelerating the wind flow.

At present, the only real option of recording vegetation in detail in an area the size of Berlin is to obtain information from databases based on aerial photography, which also allows the development of urban green spaces to be observed and accounted for.

Unlike the continuously updated data base of the Official Real Estate Cadastre Information System (ALKIS) that is available for building objects, the analysis of vegetation heights in Berlin is dependent on the 5-year intervals of the high-resolution summer aerial photography flights of the geotopography and its products (only in German, cf. Methodology). This 5-year interval, however, is deemed sufficient for the identification of trends and developments.

This map updates the vegetation height mapping based on the aerial photography flights in 2009/ 2010. This update included switching to a grid-based object reference system to simplify future updates, among other things, as well as a change analysis.