Vegetation
The lack of significant differences in the abundance, richness, and diversity of plants between urban and rural sites (Figure 4d-f) could be due to the limited spatial extent of habitat patches and the prevalence of native, unmanaged vegetation within urban green spaces on Lipsi. Whilst rural areas had significantly more shrubs and less bare ground than urban sites, there was no difference in the cover of trees, which are scarce on Lipsi, negating the possibility for greater tree cover to promote butterfly species richness (Kurylo et al. 2020). The lack of a marked difference in vegetation structure between urban and rural areas could thus be a key factor in explaining the similarity in butterfly abundance and diversity across habitats. A prevalence of non-native plant species in urban areas may prevent larval development of butterflies (Dylewski et al., 2019), but exotic species were only present at three urban sites and in low abundance, limiting their potentially negative effects on butterflies. Furthermore, butterfly abundance responds negatively to non-native plants in late spring and positively by mid-summer (Kurylo et al., 2020), highlighting the importance of greater temporal resolution of sampling to characterise vegetation effects on butterflies.
Urbanisation altered vegetation community composition (Figure 5c), with cultivated barley (Hordeum vulgare ), castor bean (Ricinus communis ), and scutch grass (Cynodon dactylon ) prevalent in urban environments, while natural Mastic shrubs (Pistacia lentiscus ), wild oats (Avena barbata ), and desert saltgrass (Distichlis spicata ) dominated in rural environments. This may have contributed to the observed differences in butterfly community composition, with cultivated patches hosting different butterfly assemblages than natural forests and scrub (Chong et al., 2014). Thus, whilst we did not detect any effect of urbanisation on the abundance or diversity of the vegetation and butterfly assemblages, the observed changes in taxonomic identity could have major implications for ecosystem functioning, which should be quantified in future studies.