02/02/2023
As temperatures in urban areas are rising, green spaces become more crucial for providing shadow and and enhance the quality of life for citizens and urban flora and fauna. Our colleagues Srđan STOJNIĆ, Claudia COCOZZA, Erna VAŠTAG contributed to this important topic with their article "DROUGHT RESISTANCE OF NON NATIVE TREES"
Introducing non-native tree species (NNT) alongsidedrought-resistant autochthonous species has been identifiedas a possible solution for increasing species diversity incities. Although there is widespread concern that biodiversityloss may occur as a consequence of harmful effectsof NNT on native species a recent study conducted inthe UK showed that 75 % of respondents would be happyto see more non-native planting in UK public spaces if theselected species were better adapted to the changing climatethan existing vegetation. It is therefore likely that the relevanceof NNT will increase under future climate changeconditions, since public awareness regarding their role insecuring the resilience of urban tree populations is rising.Accordingly, a number of studies have discovered evidenceof higher drought tolerance of NNT growing in urbanareas as compared to autochthonous species. For example,a dendroecological study conducted on several tree speciescultivated along the streets of Dresden (Germany) showedthat Quercus rubra and Platanus x hispanica are better adaptedto warm and dry conditions than Acer platanoides and Acerpseudoplatanus. Similarly, Vaštag et al. reported that.
Acer platanoides trees growing in the urban area of Novi Sad,Serbia, exhibited a more severe reduction in physiologicalperformance than Liquidambar styraciflua when subjected todrought stress. Finally, using chlorophyll a fluorescence techniqueto study the state of the photosynthetic apparatus inyoung trees of eight species and cultivars in Warsaw, Poland,Swoczyna et al. found that the three introduced speciesGleditsia triacanthos, Platanus x hispanica, and Pyrus calleryanaachieved the maximum quantum yield of photosystem IIvalues approximate to optimum regardless of their distancefrom roads and the date of the measurements.Even though the physiological condition of trees is closelylinked to their capacity to provide ecological services in urbanenvironments, high tree biodiversity should be promotedto enhance the overall resilience of urban forests to biotic andabiotic stresses. Moreover, as the stresses encountered byurban trees depend on growing conditions in urban areas(e.g., park trees and trees growing in urban woodlands are lessaffected by stress factors than trees occurring on squares), intree pits, or along roads, a variety of tree species including NNT and less commonly used autochthonous species shouldbe considered for planting in urban environments. In thiscontext, comprehensive guidance on the drought toleranceand growing potential of different tree species in variousurban conditions should be developed for specific regions,including a list of traits that could be exploited as bio-indicatorsof those species’ resistance to stresses.
Photo: Liquidambar styraciflua
