Cooling Services

As a part of the project, an investigation was conducted to test if a dense forest cover could overlap the cooling services of different peatland sites. The results (peat soil layers) were analyzed together with results from evaporation modelling (ABIMO, Goedecke & Gerstenberg 2008) of the Berlin Senate Department for Urban Development and the Environment, Dept. III (Geoinformation).

It was found out that peatlands – as compared to neighbouring forests generally show a higher evaporation. This is attributed to comparatively higher levels of groundwater at peatland sites, a parameter apparently largely responsible for the quality of evaporation even in densely forested areas. Therefore, the availability of water can be considered as a crucial factor for the quality of cooling services.

Schematische Darstellung Verdunstungsleistung

Conservative estimates of evaporation by selected forest mires of Berlin. Schematic of the peatland area in comparison to its neighbouring environment (200 m). Selection of evaporation values from ABIMO modelling (Goedecke & Gerstenberg 2008) are courtesy of the Berlin Senate Department for Urban Development and the Environment, Dept. III, Geoinformation. Modelling with own field-data was not part of the project.

The aim was to develop a practical indicator system. Thus, the cooling service of Berlin's peatlands is presented here through the availability of water as principle indicator. The starting parameter „depth to groundwater table“ is determined from soil data, vegetation data, and - where available - from long-term peatland water level data (Scheffler et al. 2013).

Following the water height concept (Koska 2001), below rating system uses three assessment grades:

Annual Median Water Level [cm ü./u.F.)

Water Height according to soil, vegetation, or peatland water level (rare)

Potential Cooling Service

Rating Scale

≤ 45 (incl. flooding) 5+, 4+, 3+ high; mire-typical good
> 45 to ≤ 80 2+, 1 moderate; mire-typical to some extent medium
≥ 80 2- low; not mire-typical poor

In order to assess a „noticeable“ cooling, the parameters „location within a cold air advection area“ (SenStadtUm 2012a) and „proximity to human settlement“ were focused on. Inner-city cold air advection areas are open spaces, which have due to their size and location a high relevance for the urban climate due to their size and location. They provide an important local contribution to the reduction of the stress from summer heat (SenStadtUm 2009). If a peatland is located outside of these areas, it is additionally tested for the parameter„proximity to settlement“. According to Horbert (2000), the influence of Berlin's ecosystems (parks and gardens) varies considerably in dependence on circulation, or advection, and wind conditions. On average, however, a range of 200 m can be assumed. If areas of settlement are in close proximity, less than 200 m, to a peatland, a measurable cooling effect can be expected there.

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