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Technical University of Munich

Methods "Colorful Ribbons for our Cities in Times of Climate Change"

Work package 1: Installation of close to nature flower areas under field trial

To enhance the ecological functionality of cities in times of climate change and to promote the trans­position of polli­nators and other useful animals from the vicinity to the city center, new flower­ing areas in lawns at verges of traffic axes will be installed (see figure 1: Project concept - promo­tion of the ecological functio­nality of urban green areas).

Fig. 1: Concept scheme of the project "Promotion of the ecological functionality of urban green spaces"

The most suitable axes in Munich are the Ingolstädter Straße from the northern Leopold­straße to the protec­ted area Panzer­wiese, the Lerche­nauer Straße, the Arnulf­straße, the Agnes-­Bernauer-­Straße, the Gott­hard­straße, the Fürsten­rieder Straße, the Rosen­heimer Straße and the Freisinger Land­straße. The so far seeded species-­poor grass mixtures will be replaced at five of these arterial roads by insect friendly, close to nature flower­ing mixtures with different wild flower covers. The flower­ing areas will connect the city center with the vicinity by the semi-­urban areas and will create a "Colorful Ribbon" following traffic axes with decreasing sea­ling and in­creasing vege­tation cover (figure 2).

 

Fig. 2: Planned set-up of "Colorful Ribbons" with novel flowering areas along main traffic axes along an urban-rural gradient. A total of five roads will be selected where the species-poor grass mixtures will be replaced by near-natural flowering mixtures. A further road without intervention will serve as a control to study ecosystem functions and services

Within each city area the colorful ribbons will extend over a maximum length of 1200 m and a minimal dis­tance of 1500 m. Therefore there is a minimal length of 6700 m necessary for the traffic axes. To enable miti­gation and trans­position of polli­nators such as wild bees and other useful animals, up to 10 flower­ing areas will be installed at each "Colorful Ribbon" (figure 3). The flower­ing areas of each city area will be installed in the greened verges in exponen­tially increasing dis­tances of 7, 20, 55, 150, 400, 400, 150, 55, 20 and 7 m. Thus it will be possible to under­stand the direction of the miti­gation as well as the optimal dis­tances between the flower­ing areas by capture-­recapture, tint bowls and nesting aids. 

 

Fig. 3: Diagram showing the layout of flowering areas and the detection of pollinators and other beneficial organisms using paint bowls and nesting aids as a flowering ribbon on middle strips of traffic routes. By recording pollinators and other beneficial insects at exponential intervals, it is possible to determine both the optimal distance between flowering areas and the direction of exchange (from the city to the surrounding area or vice versa)

Because the interactions of the flowering areas with their surrounding environment are a main focus of our pro­ject, the other functions of the experi­mental plots (amount of green, seal­ing), dispersal barriers for polli­nators (bridges, sub­ways) and the distance to the vicinity will be analysed.

For each flowering area three adjacent to one another plots of an area of 2 m x 3 m will be installed. The instal­lation of these flower­ing areas will be done with standar­dized species mixtures with a high attrac­tivity for polli­nators and other useful animals. They conform commercial available "mixtures for traffic islands" with annual and perennial wild plants of local origin. Especially attrac­tive species for polli­nators are Centaurea cyanus, Knautia arvensis and Teucrium chamaedrys.

The aim of this field trial with multifunctional seed mixtures for urban areas is the extensive establish­ment of flower­ing areas by inte­gration of rare species and attractive flower­ing aspects for as long as possible. The city wide design of the project enables the investi­gation of the importance of the spacial arrange­ment of flower­ing areas for bio­diversity and urban climate adap­tation.

Work package 2: Promotion of pollinators and other useful animals

The relevance of flowering areas as food habitat for pollinators (hymenopterous insects, diptera, butterflies) and other useful animals (lacewings, ladybugs, hoverflies) will be analysed with tint bowls. The investigations will be conducted during the main flowering time of flowering plants from the beginning of May to the end of September.

To analyse the quality of flowering areas as nesting habitats, nesting aids will be placed. For each flowering area, two flowering areas will be placed from spring to fall. After collection, the closed reed stems will be controlled, opened and all pollinators and other useful animals identified.

 

To further investigate the influence of flowering areas on the movement and fly distances of selected insect species, the pathways of tagged individuals will be captured by capture-marking-recapture-method and direct monitoring. By combining these two methods it is possible to optimize the distances between flowering areas and adjust their design to enable an effective exchange of insect populations between single flowering areas.

Work package 3: Recording of the climate regulation function of the flowering areas

In this project part the influence of flowering areas on the urban micro­climate and the ­resilience of flower­ing areas against heat and drought stress will be ana­lysed. The stand climate will be evaluated at selected flower­ing areas along the city-­vicinity-­gradient and compared with data of un­treated green areas. Therefore during summer months in the field, a small, self-registering thermal and soil humidity logger.

At the TUM-mesa climate chambers the establishment and development of mixtures regarding their bio­­mass and flower produc­tion will be studied, under the influence of heat waves, drought and flooding stress. The experi­ments at the climate chambers will be comple­mented by outdoor seedings at the experi­mental station Dürnast of TUM.

Work package 4: Study of the sociocultural acceptance and of the economic value of the flowering areas

The attractivity and the acceptance of the flowering areas in the city center, in peri-­urban areas and in the vicinity within the popu­lation will be evaluated by standardized question­naires of passersby's and residents. An interview with the heads of divisions using open, semi-­open and closed questions will clarify, under which condi­tions the munici­palities will accept the long-­term establish­ment and mainte­nance of multi­functional flower­ing areas at traffic axes and where a need for opti­mization is required.

For the holistic balancing of economic, nature conservation and/or social aspects of the establish­ment of close to nature flower­ing areas at traffic axes in comparison to conventional green areas, profound life cycle assess­ments will be developed in cooperation with the munici­palities. The assess­ment will be based on (1) environ­mental balance, (2) analysis of the costs of life cycle assess­ments and (3) a social life cycle assess­ment. The compari­son of these three assess­ment methods will show, where conflicts of aims with the different compo­nents of the project might arise. This holistic view will enable us to strengthen the aware­ness of munici­palities and citizens about a sustainable utilization of urban green areas

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