**5. Conclusions**

The Mediterranean agricultural landscape expressed by the olive tree has unique features, and it is still possible to find numerous monumental individuals in it, extraordinary for their age, shape, and size. They constitute authentic milestones both for the expressiveness they impress on the agricultural landscape, of which they are the significant elements and for the conservation of the precious germplasm of which they are custodians. The monumental olive trees represent, in fact, a reservoir of genetic diversity, which includes characteristics associated with resilience and adaptation to specific environmental conditions and which has allowed for resistance for several centuries, some for over a millennium, to the action of climatic agents, parasitic and anthropogenic activities, and the passage of fire. Therefore, they constitute the best guarantee for the future of olive growing, a sector of agricultural production that is fundamental for maintaining the Mediterranean identity, from an environmental, food, and social point of view.

The survey of secular olive trees, in addition to the considerable interest it holds in the context of the characterization and typification works of the olive-growing heritage, is also important from an eco-touristic point of view, being able to represent the destination or one of the major attractions of naturalistic itineraries within agroecosystems.

On the basis of the results of this paper, the following general recommendations should be taken into account for the conservation of monumental olive trees:


**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/10 .3390/su13126767/s1. Table S1: List of the 367 monumental olive trees sampled in Sicily.

**Author Contributions:** Conceptualization, R.S. and G.B.; methodology, R.S.; investigation, C.S., F.A., G.D.N., P.M., and P.R., data curation, R.S. and A.G.; GIS analysis and mapping, G.B; writing—review and editing, R.S., G.B., C.S., and A.G.; supervision, R.S.; funding acquisition, R.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** Financial support was received from "Fondo di Finanziamento della Ricerca di Ateneo (FFR2019)".

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors would like to thank the anonymous reviewers for their helpful readings and suggestions that improved the overall quality of the text.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Dedication:** The authors wish to dedicate this article to the memory of Rolando Juan Carlos León, Professor of Ecology at the Faculty of Agronomy of the University of Buenos Aires, who loved Sicily and its biodiversity (Figure 3c).
