Native pedunculate oaks support more biodiversity than non-native oaks, but non-native oaks are healthier than native oaks: A study on street and park trees of a city br

Trees in cities provide multiple ecosystem services. However, simultaneously ensuring healthy trees with high habitat di-versity can be challenging in a harsh urban environment. We compared health, microhabitats, and bat activities between native (Quercus roburL.) and non-native (Quercus rubraL.) oaks growing in different urban habitats (street vs. park) in Karlsruhe, southwestern Germany. We randomly selected 167 oak trees with a diameter at breast height (DBH)>20 cm across the city from Urban Tree Registrar. We performed tree health assessment, dendrometric, and microhabitatinventory. We recorded the four-day bat activities on 45 native and non-native oaks with acoustic loggers installed on thetrees. We found that non-native oaks were healthier than native oaks but provided less abundance and richness of micro-habitats. Tree size (positive effect) and pruning (negative effect) strongly influence microhabitat richness and abundance.In addition, park trees hosted significantly more microhabitats than street trees. We recorded the activities of 9 bat speciesfrom 4 genera.Pipistrellusbats were more active in park trees than street trees. Long-eared bats (Plecotus)weremoreactivenear the native than non-native oaks. Bats are likely favored bymicrohabitatssuchasforksplit, lightning scar, and wood-peckerflutethat are more common in less healthy trees. We conclude that non-native red oak can be planted alongsidestreets, where the conditions are harsher than in parks to better adapt to climatic changes and stay healthy with less main-tenance. The preservation of native pedunculate oak trees, especially within parks, is paramount for urban biodiversity conservation because of their potential to provide microhabitats and supporting bats

Automated summary

Trees in urban areas provide various ecosystem services, but maintaining healthy trees with high habitat diversity can be challenging. This study compared the health, microhabitats, and bat activities between native and non-native oak trees in different urban habitats in Germany. The results showed that non-native oaks were healthier but provided fewer microhabitats than native oaks.