Keywords

1 Introduction and Background of Research

The olive tree is considered the most emblematic tree, inextricably linked with the history, culture, Mediterranean landscape, and economy of the peoples [1]. Its cultivation dates to the Bronze Age, while olive products seem to have been exploited since the Mesolithic era [2]. Since this period it has had a wide distribution in all the Mediterranean countries and our days it is estimated that in the Mediterranean are cultivated about 800 million olive trees [3, 4].

A perennial olive tree, in many cases, exceeds a millennium. As a tree has a very slow annual growth, offers products for hundreds of years and its trunk creates impressive shapes, curvature, and cavitations, elements which make the tree unique and can be classified as a monument of nature [5]. Moreover, contributes to the preservation and increase of biodiversity, offering housing, security, and food to many species of fauna and flora [6,7,8].

According to Caracuta [4], the wild olive tree and its use date to the Epipaleolithic era in the region of Israel [4]. Besnard [6] states that it is most likely the first crop from western Iran and as it spread to other geographical areas and new varieties evolved. It is undeniable that the cultivated olive trees (Olea europaea var. europaea) come from the improvement of the wild olive trees (Olea europaea var. sylvestris), which slowly spread throughout the Mediterranean. In our days, this emblematic species defines the Mediterranean climate type/zone [8]. According to Zohary and Hopf [9], in Mediterranean countries, the olive tree was one of the first fruit-bearing plants to be domesticated, perhaps as early as the 5th millennium BC, as evidenced by the various constructions in Mediterranean countries such as Jordan, Greece [10].

Today the olive tree, alongside with the vineyard, represents the traditional Mediterranean products [11]. Monumental olive trees and, in general, all monumental trees, with their longevity contribute to other research fields, such as dendroclimatology, archaeometry, historical ecology, biodiversity, etc., while at the same time, they are also connected to humanities and social sciences, exploring the interpretation of historical events and the evolution of the traditional rural landscape. Olive trees tell the story of the Mediterranean landscapes and the evolution of the cultural heritage of each place through the centuries and are connected with sustainable development and sustainable tourism [12].

While many studies have focused on the role of olive groves in shaping the Mediterranean landscape, e.g., [13,14,15], not much emphasis has been placed on highlighting the values of monumental olive groves and olive trees and their great cultural/biocultural value and their contribution to sustainable tourism [5, 16, 17].

Under the frame of the “Biomemories” project, implemented by the Ionian University, concerning the Monumental Olive trees at the Ionian Region, we have recorded, and mapped the monumental olive groves and trees at different Islands. At this research, we highlight the monumental olive trees of the Ionian (Fig. 1) and propose trails throughout the monumental olive groves and olive trees. The aim was to protect these unique natural monuments and develop the rural sustainable tourism at the Ionian Islands.

Fig. 1
3 photographs of monumental olive trees. The left-most and right-most photographs display a female and male, respectively, beside the olive tree.

Some of the monumental olive trees of the Ionian Islands

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1.1 Study Area

The Region of the Ionian Islands is an island Region, which was formed mainly based on its common historical and cultural past. The islands that consist it, stretch along the western coast of Greece. The Region has a total area of 2318 km2, covering 1.8% of the total area of the country. It includes the Islands of Zakynthos, Corfu, Kefalonia, Ithaca, Paxoi and Lefkada (Fig. 2). The Region has 32 islands, of which only 13 are inhabited.

Fig. 2
A map of Ionian islands on a scale bar of 0 to 50 kilometers. It indicates the agricultural areas, artificial surfaces, forest and semi-natural areas, water bodies, wetlands, and others. An inset map marks the study area.

Ionian islands—study area

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The climatic conditions in the Ionian Islands are Mediterranean-type, with mild and relatively wet winters and hot and dry summers. The average temperature of the Region ranges from 8.7 °C in January to 26.5 °C in July. The islands are characterized by a high average annual rainfall. Most rainfall occurs in the period of October–February (rainy region), while snowfall in the winter months is extremely limited in the mountainous areas.

In the Ionian Islands region, there are many areas of rare natural beauty and significant ecological importance with a notable number of protected areas. One of the most important characteristics of the Ionian Islands is the monumental olive groves and trees, with rich biodiversity, which form a special agroforestry ecosystem of high natural and cultural value. There are olive trees whose circumference (at 1.30 m. height) exceeds 18 m and the estimation of their life is 2.605 years.

2 Methodology

In this section, a detailed explanation of the methods and procedures used to conduct our research is presented. This section is structured in a way that allows other researchers to replicate our study in other areas of different ecosystems, if necessary.

2.1 Literature Review and Design

During this step, a literature review has been conducted in addition to research for the definition of the criteria that are used for the characterization of olive groves and olive trees as monumental. These criteria are further used to establish a framework for registering and connecting olive groves with the historical and cultural heritage of NATURA 2000 areas, specifically focusing on the islands of Zakynthos, Kefalonia, Lefkada, Corfu, and Paxos. This framework is essential because the estimated value of each tree could be calculated and the olive trees with the highest values in each area could be selected to be promoted for ecotourism [5].

2.2 Locating, Recording, and Mapping Olive Groves

After having completed the framework, within this step, field surveys have been conducted to locate and record monumental olive groves and olive trees within the NATURA 2000 areas of the specified islands. Additionally to fieldwork, satellite data have been utilized for long-term monitoring of changes in these olive groves. All this information has been used to record and document environmental and morphological data for the olive groves in the area of research, which is the Ionian Islands.

2.3 Tree Dating with Radio Carbon Dating (14C), Annual Rings, OSL and IRSL

During the third step, a representative sample of monumental olive trees (75 samples) from Zakynthos, Kefalonia, Lefkada, Corfu, and Paxos was selected. These samples have been examined using the three methods and the estimated age of the olive trees has been used to find the oldest olive trees.

2.4 Investigation of Bioactive Substances in Olive Oil

After having estimated the age of the olive trees, the olives have been collected and laboratory analysis has been performed to investigate the presence of bioactive substances in the collected olive oil. The results show that the olive oil of the monumental olive trees has a special nutritional value.

2.5 Biodiversity and Habitat Recording

In selected monumental olive groves, either within or near the NATURA 2000 areas of Corfu, Kefalonia, Lefkada, Paxos, and Zakynthos, we recorded biodiversity and habitats.

2.6 Protection, Promotion, and Ecotourism Actions

At the last stage, a comprehensive action plan was developed for the protection, promotion, and ecotourism exploitation of monumental olive groves within the NATURA 2000 areas of Zakynthos, Kefalonia, Lefkada, Corfu, and Paxos. During this stage, the initially mapped trails in the islands have been finalized and a trail connecting the different islands has been verified. Furthermore, island hopping has been described and preservation initiatives, promotional campaigns, and ecotourism programs have been implemented.

3 Results—Trails

This study involves digital mapping of routes through selected heritage olive groves on all the Ionian Islands. Monumental olive groves, and particularly the determination of the age of ancient trees, play a crucial role in various scientific fields related to management, environmental sciences, dendroclimatology, and historical, and cultural heritage. Moreover, this research highlights the potential for contributing to the Sustainable Development of the Ionian Islands by showcasing unique biodiversity and cultural traditions, while informing local communities and promoting sustainable tourism.

The selection of trails was carried out after recording and mapping significant heritage olive groves on the islands of Zakynthos, Kefalonia, Lefkada, Corfu, and Paxos. The use of Geographic Information Systems (GIS) and remote sensing data, assisted in mapping these trails and their ecological characteristics, with a focus on rich biodiversity and historical context. The trails were carefully curated to provide visitors with the natural beauty and ecological diversity of the olive groves. Furthermore, interpretive signage and educational materials along these paths offer visitors a deeper understanding of local flora and fauna, emphasizing the importance of preserving these ecosystems for future generations.

The trails exemplify a harmonious synergy between tourism and sustainable development in the Ionian Islands and educate local communities about agroecological techniques and organic farming, encouraging the use of environmentally friendly approaches that preserve biodiversity and soil health. They provide visitors the opportunity to closely admire monumental trees, and the Ionian landscape, and immerse themselves in the region's history and traditions. Furthermore, it is expected that these trails in the monumental olive groves will be interconnected with other thematic routes in the Ionian region, aiming to create a network with the prospect of certification and integration into relevant European networks. This adds a sustainable development perspective to the mountainous and rural communities of the Ionian islands (Figs. 2, 3).

Fig. 3
A copy of a page from a brochure with illustrations of 5 maps. Each presents a trail each of the Ionian islands with arrows pointing to the next, from left to right. It has a listicle each with text in a foreign language.

Routes in the Ionian islands

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This work integrates scientific research [5] with practical application, opening new prospects through the creation of innovative and sustainable initiatives with immediate feedback to local communities. This is in accordance with the institutional framework and international practices for the preservation of natural and cultural wealth, particularly in NATURA 2000 areas.

4 Conclusions

Monumental olive groves and olive trees are considered ecosystems of high ecological and cultural value, which also constitute a reservoir of genetic diversity, with characteristics linked to longevity and adaptability to the action of many factors such as climate variability, anthropogenic factors, parasitic invasions, fires, etc.

Promoting monumental olive trees as a thematic priority for sustainable tourism can have several economic, environmental, and cultural benefits. Olive trees are not only a symbol of history and tradition but also a valuable natural resource with numerous sustainable development implications: Biodiversity Conservation: Old olive groves often host diverse ecosystems with unique flora and fauna. Sustainable Agriculture: Olive farming, when done sustainably, can be a model for eco-friendly agriculture. It often involves organic practices, agroecology’s approach, minimal water usage, and low environmental impact. Economic Opportunities: The olive industry provides employment and income to rural communities. Emphasizing the importance of monumental olive trees can stimulate economic growth in these regions, including tourism, olive oil production, and artisanal products. Cultural Heritage: Ancient olive trees are often deeply embedded in local cultures and histories. Preserving them helps maintain cultural identities and can boost cultural tourism. Tourism and Education: Monumental olive trees can attract tourists interested in nature, history, and sustainable practices. Interpretive centers and guided tours can educate visitors about the importance of these trees and sustainable practices. Research and Innovation: Prioritizing monumental olive trees can lead to research into better cultivation methods, disease prevention, and the development of sustainable products derived from olives and olive trees. Sustainable Development Goals (SDGs): Promoting the conservation of monumental olive trees aligns with several SDGs, including SDG 15 (Life on Land), SDG 13 (Climate Action), SDG 8 (Decent Work and Economic Growth), and SDG 11 (Sustainable Cities and Communities). Community Empowerment: Involving local communities in the conservation and sustainable management of olive groves can empower them economically and socially, fostering a sense of ownership and responsibility. To make monumental olive trees a thematic priority for sustainable tourism, it’s essential to engage various stakeholders, including governments, local communities, NGOs, and the private sector.