**3. Results**

The collected dataset represents a heterogeneous sample for dendrometric parameters and environmental contexts. There are 367 specimens, 364 of which are *Olea europaea* var. *europaea* and 3 of which are *Olea europaea* var. *sylvestris*, of considerable size found in different Sicilian provinces (Figure 1). Of these, a significant part is located in the provinces of Agrigento, Messina, Palermo, and Syracuse. The collected data were computerized to facilitate its management, consultation, and implementation over time. A significant example of the surveyed specimens, divided by regional province and referring to 50 individuals, is reported in Table 1. Of 367 specimens, 74 are part of the province of Agrigento, 73 are of Messina, 64 are of Palermo, 56 are of Syracuse, 30 are of Trapani, 21 are of Ragusa, 20 are of Catania, 16 are of Enna, and 13 are of Caltanissetta (Figure 2).

**Figure 1.** Distribution of 367 monumental olive trees of Sicily represented by classes of stem circumference (at root collar).

**Table 1.** Sample of the 50 most significant monumental olive trees. The complete list of specimens is given in the supplementary materials.


With reference to the maximum circumference value of the stem (measured at the collar), 11.4% of them have circumference values equal to or less than 4 m; 30.5% have values between 4 and 6 m; 31.3% have values between 6 and 8 m; 14.2% have values between 8 and 10 m; 7.1% have values between 10 and 12 m; 2.7% have values between 12 and 15 m; 2,7% have values greater than 15 m.

Considering the age of the surveyed plants, 7.1% of them are between 200 and 400 years old, 26.4% are between 400 and 600 years, 33.5% are between 600 and 800 years, 15.3% are between 800 and 1000 years, and 17.7% over 1000 years.

**Figure 2.** Distribution of monumental olive trees in the Sicilian provinces.

In particular, examining the data relating to the aforementioned sample, it is possible to argue that, in the province of Agrigento, there are several extraordinary olive trees among which, in addition to the very suggestive ones of the Greek Valley of the Temples, there are some plants of about 800–1100 years present in the municipalities of Agrigento (Figure 3a), Caltabellotta (Figure 3b), and Sciacca, with circumference values ranging from 6 to 17 m. Additionally noteworthy is the Olivastro di Inveges, located in the Sciacca area, full of history and legends, with a stem of about 5 m in circumference.

In the province of Caltanissetta, the largest olive trees are found mainly in the territory of the chief town, in the Canalotto-Mimiani, Vituso, and Bugini districts. These are ancient specimens with maximum circumference values between 5 and 11.40.

In the province of Catania, among the most beautiful monumental olive trees, there are specimens along the millenary olive tree road, in the municipal area of Motta S. Anastasia, with specimens up to 8 m, while in the province of Enna, there are ancient specimens with a maximum circumference between 3.40 and 14.1 m.

Among the most noteworthy olive trees in the province of Messina, aged between 414 and 2081 years, we can mention those present in the Nebrodi mountains territory, with particular reference to the area between Tusa, Pettineo, Acquedolci, and Caronia. In particular, the Predica area of the latter municipality contains one of the most relevant examples (Figure 3d). It has a maximum circumference of 12.9 m at the stump and a monocormic stem of 9.30 m at breast height, with various ribs with rounded edges, cavities, and grooves that, from the insertion of the crown, reach the ground. This specimen, over 1360 years old, can most likely be considered one of the largest olive trees in Sicily and Italy.

Among the numerous other notable specimens for age, shape, and size, we remember those of the Maviti and Innari areas in the territory of Pettineo (Messina): the first (Figure 3c) consists of a large stump of about 10.8 m in circumference, surmounted by two trunks of particular beauty, for shape and bearing, of 6.30 and 4.50 m in circumference to breast

height; the second has a large stump of 19.60 m in circumference surmounted by three trunks with a breast height circumference of 4.60, 2.90, and 2.40 m, respectively.

**Figure 3.** Some of the monumental olive trees of Sicily: (**a**) Olivo grande di Bonamorone (Agrigento); (**b**) Olivi di Caltabellotta; (**c**) Olivo di Contrada Maviti (Pettineo); (**d**) Olivo di Predica (Caronia); (**e**) Olivo di Calabrò (San Mauro Castelverde); and (**f**) Olivo di Busulmone (Noto).

Several olive trees in the province of Ragusa, distributed in the municipalities of Chiaramonte Gulfi, Acate, Modica, and Ispica, are striking for their bizarre shapes and sizes. In the territory of the latter municipality, there is an extraordinary olive tree of Scorsone of about 1115 years, with a maximum circumference of 10.5 m at the collar.

In the territory of Siracusa, extraordinary olive trees can be found in Buccheri, Noto, and Avola. The most representative are certainly those of the Busulmone district (Noto), which, with a circumference of 12.60 m at the level of the stump and 7.20 m at breast height, are probably 1338 years old (Figure 3f), and those of the area La Gebbia (Avola) with a circumference of 15.50 m at the collar and 10.10 m at breast height.

In the territory of the province of Palermo, considerable olive trees are found in the municipalities of Caltavuturo, Carini, Misilmeri, Palermo, Pollina, San Mauro Castelverde (Figure 3e), and Vicari, where several individuals with very large stumps show maximum circumference values of up to 19 m.

In the province of Trapani, worthy of consideration are several ancient olive trees present in the municipalities of San Vito Lo Capo, Castellammare del Golfo, Castelvetrano, and Trapani, which have maximum circumference values between 3.5 and 12 m.

The secular olives are located at an altitude ranging from 24 to 841 m asl, showing a distribution with an average value of 304 m and a standard deviation of 175 m. The distribution of olive trees across soil types shows no significant effect of substrata, indicating the plasticity of the species. A total of 267 specimens grow on basic lithotypes (limestone, dolomite, marl, gypsum, and calcarenite), and 94 grow on acid lithotypes (vulcanite, flysch, and quartzite).

Only four trees fall within the regional natural reserves, eight are located in Madonie Natural Park, and five are in Nebrodi Natural Park.

Concerning the structure and habit of growth, the tree crown diameter varies from 7 to 15 m and, in the case of irregular shape, ranges from 5 to 13 m in the N–S direction and from 4 to 15 m in the E–W direction. The height of the surveyed plants changes between 5 and 15 m, in relation to the different techniques of pruning or in relation to the state of cultural abandonment or in order to maintain the foliage at a level that allows the grazing of livestock without damaging plant production.

Vegetative and health conditions are excellent in 4.9% of specimens, good in 24.8%, fair in 53.7%, mediocre in 14.4%, and poor in 2.2%.
