Comparisons of herbivory on native and non-native plants in botanical gardens in Europe
The ‘Enemy Release’ hypothesis states that the invasion success of non-native species is due in part to their escape from natural enemies that keep the species in check in their native range. Released from this natural enemy pressure, non-native species can invest more into growth and fecundity and be better competitors than their native counterparts. To evaluate if reduced natural enemy damage (insect herbivory) is beneficial to the naturalisation of non-native plants, surveys were conducted in 2007-2021 in 15 botanical gardens across Europe. Botanical gardens across the world hold some 30 % of all plant species and have in some cases, contributed to the introduction of invasive alien plants. The botanical gardens in this study spanned from Bern (Switzerland) to Trondheim (Norway). In each botanical garden, as many species as possible were randomly sampled and details on the species, plant growth parameters and levels of herbivory were collected. Only plants growing outside were included in the study. In total, 5 986 individuals were surveyed including 2 752 plant species. Overall, herbivory levels were lower on non-native plants compared to native plants. However, non-native plants which are naturalised in Europe had similar levels of herbivory to native plant species. The results suggest that for some plant species which have become naturalised, herbivory may not affect their competitive ability.
Sources
Ivison K, van Kleunen M, Speed JDM, Vange V, Pujara S, Boch S, Enters D, Groom Q, Janovský Z, Jeschke JM, Josh J, Kolb A, Kollmann J, Koubek T, Lemke T, Matthies D, Raabová J, Tielbörger K, Dawson W (2024) Non-native, non-naturalised plants suffer less herbivory than native plants across European botanical gardens. Diversity and Distributions, e13938. https://doi.org/10.1111/ddi.13938