The present status and potential distribution of relict populations of Aesculus hippocastanum L. in Greece and the diverse infestation by Cameraria ohridella Deschka & Dimić

Aesculus hippocastanum is a well-known species, which is popular because of its ornamental value. However, data on the demographic structure and potential distribution of A. hippocastanum are limited. The invasion of Cameraria ohridella into Europe has harmed those trees growing in artificial sites, but the presence of this insect in natural stands has been little studied. Here we aimed to investigate the demographic structure infestation level of natural populations of horse-chestnut. Additionally, Maxent modelling was used to predict the potential range of A. hippocastanum, based on the localities available in the literature. Field data analysis indicated that natural populations of A. hippocastanum are mostly found nearby mountain streams. The populations showed a diverse height structure and large numbers of seedlings, which indicate high population dynamics. The level of infestation by C. ohridella varied greatly and correlated with altitude. Secondary infestation might explain this infestation variability in some natural populations. Other hypotheses, such as environmental resistance factors or different genetic variability, are also discussed. By spatial distribution modelling, we found that the precipitation of the coldest and warmest quarters, as well as altitude, are important factors influencing the potential distribution of A. hippocastanum.