The Influence of Individual-Specific Plant Parameters and Species Composition on the Allergenic Potential of Urban Green Spaces

Abstract

Green planning focusses on specific site requirements such as temperature tolerance or aesthetics as crucial criteria in the choice of plants. The allergenicity of plants, however, is often neglected. Cariñanos et al. (2014; Landscape and Urban Planning, 123: 134-144) developed the Urban Green Zone Allergenicity Index (I UGZA) that considers a variety of plant characteristics to calculate the allergenic potential of urban green spaces. Based on this index, we calculated an index for the individual-specific allergenic potential (I ISA) that accounts for a varying foliage volume by accurate measurements of crown heights and surface areas occupied by each tree and only included mature individuals. The studied park, located in Eichstätt, Germany, has an area of 2.2 ha and consists of 231 trees. We investigated the influence of species composition using six planting scenarios and analysed the relationship between allergenic potential and species diversity using Shannon index. Only a small number of trees was female and therefore characterised as non-allergenic, 9% of the trees were classified as sources of main local allergens. The allergenic potential of the park based on literature values for crown height and surface was I UGZA = 0.173. Applying our own measurements resulted in I ISA = 0.018. The scenarios indicated that replacing trees considered as sources of main local allergens has the strongest impact on the park's allergenic potential. The I UGZA offers an easy way to assess the allergenic potential of a park by the use of a few calculations. The I ISA reduces the high influence of the foliage volume but there are constraints in practicability and in speed of the analysis. Although our study revealed that a greater biodiversity was not necessarily linked to lower index values, urban green planning should focus on biodiversity for ameliorating the allergenic potential of parks.

Impact of Plane Tree Abundance on Temporal and Spatial Variations in Pollen Concentration

“…Due to the local provenance of plane tree pollen (as distinct from pollen generated by vegetation growing outside cities), dispersal takes place over shorter distances [58,59]. This is especially relevant in the case of large urban areas containing monospecific stands of an allergenic ornamental species, which pose an enormous risk to allergic citizens making use of these green spaces [23]. Major influential factors therefore include not only the number of individual trees constituting major sources of pollen, but also the distribution of these trees within cities.…”

“…Prediction models are currently being developed for ornamental species, with a view to assessing the allergy risk in urban green spaces [21], and recent research has focused on evaluating the risk posed by urban green spaces as a function of the presence and abundance of certain species [14,22,23].…”

Ash pollen season in Poland in 2019

“…Still, more research is required regarding the use of allergenic plants in green spaces and the development of allergy-friendly green areas in urban environments. Some attempts have been made to formulate planning recommendations to reduce negative health impacts caused by plants producing allergenic pollen [14]. For example, it was recommended to develop gardens with only female plants or with a great diversity of non-allergenic plants [15].…”

Lidar-Derived Tree Crown Parameters: Are They New Variables Explaining Local Birch (Betula sp.) Pollen Concentrations?

“…When planning urban green areas and selecting tree species, the needs of allergy sufferers are rarely considered [72,73]. Allergenic tree species are commonly planted in cities [74], and birch is a great example because of its ornamental functions and resistance to air pollution [75,76]. The results of the present study emphasise the importance of inventorying urban allergenic tree species; specifically, the pollen concentration was relatively high when we considered the winds blowing from Poznań city to the pollen trap in the city outskirts (Table 1).…”