|Ancient Olive Groves|
The value of ancient olives
No other plant is so present in the history and culture of the Mediterranean people as the olive (Olea europaea L. ssp. sativa Hoffman & Link, synonym Olea europea L. subsp. europaea).
Cultivated since ancient times and honoured by the Greek (according to Greek mythology, Athena planted the first olive tree in Greece), in many cultures it is regarded as one of the most famous symbols of peace. In the Jewish religion, olive oil was used in sacred rituals: prophets and kings were anointed as a sign of investiture of their royalty, hence the Hebrew word Mashiah (Messiah) or Khristós in the ancient Greek language which means “the Lord is anointed”.
The olive, probably native to Syria, was introduced to Asia Minor, Egypt, Greece, Italy and other Mediterranean countries. Cultivation by man allowed to extend significantly its geographical distribution and today it covers a wide area from Punjab, at the foot of the Himalayas, to the Azores islands and the Canary islands in the middle of the Atlantic ocean, along the region including Iran, the Near East, Anatolia, the southern Balkans, the Italian peninsula, Southern and Central France, the Iberian peninsula and the whole pre-Saharan belt.
As a result, the species is highly adapted to a wide range of environments, different soil and climatic conditions, and at the same time its genetic traits, including the seed germination characteristics, are particularly variable.
Figure 1 – Comparison between the Mediterranean watershed limits, the olive biogeographic area and the borders of the Mediterranean countries (source: Gaussen and De Philippis – FAO)
The olive, like a limited number of economically important species, is still found wild: the species commonly known as oleaster (Olea europea L. var. sylvestris Miller-Brot) is a typical component of the Mediterranean shrublands.
This species has a bushy, branching pattern, dark-green leaves and smaller fruits compared to the olive. The oleaster pulp is finer, with a lower oil content than the domesticated species. Its main economic use has traditionally been that of grafting.
The groves, above all those where ancient olives are cultivated following traditional environment-friendly practices, play a crucial role, like the shrubland vegetation and the forests, to combat the effects of wind and water erosion and to control soil loss and organic matter impoverishment. Moreover, these plants greatly contribute to mitigate the causes of desertification; in areas with little forest cover, olive groves represent a valuable carbon sink, that can trap large amounts of carbon dioxide (six years after being planted, a young olive orchard can retain up to 55 k of CO2/plant).
These agrarian systems also play an important ecological role: the “historical” olive groves represent a semi-natural environment which has remained unchanged for many centuries. They include 50-60 plants per hectare, grown extensively, sometimes with an irregular spacing following the original location of the oleaster. They are often surrounded by a dense net of dry-stone walls near which some wild shrubs (that were usually removed in the past to be replaced by the crops) still survive. Such a habitat has a great cultural and landscape value and is home to a tremendous diversity of flora and fauna communities. The traditional cultural practices (different from those applied in intensively grown orchards, but always aimed at a high yield) create a variety of structural conditions that allow the diversification of plant and animal species. Some of them are protected under the Habitats Directive (92/43/EEC). Some bird species e.g. the tit, the long-eared owl, the hoopoe and the magpie can nest in the hollow and twisted trunks of age-old olive trees. In particular, the magpie is the species which has most profited from the changes of the territory and has therefore colonized all anthropic environments.
Many other migratory birds are found in cultivated areas where they search for food; the robin and the starling are very commonly observed in the olive groves in winter, whereas white and yellow wagtails are frequently sighted near animal farms where they search for insects in the manure heaps.
Threats to ancient olives
Ancient olives face a constant barrage of threats posed by some unsound farming practices.
Loss of biodiversity due to the poor knowledge of ancient olive nature value.
The ancient olive groves are cultivated extensively and they are often characterised by distinctive structural elements e.g. hedges, cultivated strips, trees, wild shrubs and as long as they are grown traditionally they can be regarded as high nature value farmlands (EEA, 2004). Based on the definition of High Nature Value Farmlands, these areas can include not only sites of nature conservation interest or rare species, but also a number of common and widespread species which need monitoring and protection.
The ancient olive groves are agro-ecosystems that have several functions and provide some services (Millennium Ecosystems Assessment, 2002) which can be shortly described as follows:
The poor knowledge of the above services explains why, as it occurs for most world’s endangered ecosystems, these areas are not properly exploited in macroeconomic terms and why they are subject to the same market logics applied to productive farmlands as the fruit orchards or the vineyards.
Intensification of farming practices
Intensive agriculture has a strong impact on the environment. Mention should be made of repeated tillage and the use of increasingly powerful and heavy machines which cause soil compaction and greatly decrease water and soil gas permeability, degrade the soil structure and therefore, reduce soil ability to host the rich micro-fauna. These practices, if applied on steep soils or on soils where surface water is not properly managed, can induce heavy surface erosion and depletion of organic matter. As a result, a significant loss of fertile soil is often reported. Continuous tillage to control weeds and the lack of cover crops make the soil particularly exposed to the typical Mediterranean heavy and intense rainfall in autumn-winter, with an adverse effect in terms of soil and organic matter depletion. In the Spanish region of Andalusia over 80 million tonnes of soil are estimated to be lost every year in olive growing areas.
The application of pesticides and herbicides and the incorporation of fertilisers contaminate the environmental matrices (soil and water), leave residues in the plants and favour their accumulation in the food chains and in the agricultural produce (oil and olives).
Trickle irrigation, applied in many intensively grown olive groves in the Mediterranean region, induces soil salinization, above all along the coastal areas. In intensive olive orchards irrigation is indispensable because of the limited soil volume which can be explored by the root systems. Olive groves are increasingly irrigated in the areas characterised by heavy water shortage as Crete, the region of Apulia in Italy and the region of Andalusia in Spain. In this area a water deficit of 480 million m3 was recorded in 1997 and 300 million m3 were consumed for irrigation on olive farms. The ongoing intensification of olive growing (the planting density can vary from 250 plants /ha up to 1800 plants /ha in super-intensive groves) contributes to soil degradation in the Mediterranean region.
Other effects on the environment are related to cultural practices like pruning; the extension of pruning intervals, also justified by the high labour cost, causes a heavy reduction of the trees canopy and of their ability to host the avifauna.
Mechanisation, along with intensification of olive husbandry, are not compatible with terraces or dry-stone walls; this is why the linear infrastructure – which often represents the last shelter for plant and animal species and a useful means to preserve soil humidity – is removed, with a strong impact on the landscape.
Abandonment of olive growing areas due to low profits and depopulation of rural areas
The CAP reform of 2003 (Council Regulation (EC) No 1782/03) decoupled production and direct subsidies to olive growers and introduced the “single payment scheme” according to which farmers receive payments provided that they meet certain standards concerning plant health and the environment and keep their land in good agricultural and environmental condition. (cross-compliance). This policy will probably lead to further decrease the olive growers’ profit and divert their attention from ancient olives which, therefore, run the risk of being abandoned. This might eventually cause the degradation of infrastructure used for land preparation and surface water management (dry-stone walls, canals etc, …), with a deleterious effect on the environment, and favour erosion.
Lack of or limited protection policies
Many High Nature Value Farmlands are not part of the protected areas and this is a major limitation to their maintenance because they should be given much more attention not only in terms of preservation but also in terms of development (since they are productive agricultural areas). The preservation of the most important flora species and of the vegetation in these farmlands entails the strengthening of the existing legislation and the implementation of new rules, also through concerted actions involving national and international institutions, experts and farmers.
The regional Law n. 14 of 4/06/2007 “Protection and enhancement of the monumental olive trees landscape in Apulia” is aimed at preserving and enhancing ancient olives, although scattered throughout the territory, due to their productive and ecological role, their ability to provide hydrogeological protection, their value for the history, the culture and the landscape of the region. To date this regional law is the only one of its kind in Europe.
Removal of ancient olives for ornamental purposes
Over the last years many ancient olives have been uprooted and sold to decorate the gardens of luxury villas, thus impairing the Apulian landscape in terms of historical and cultural heritage, vegetation resources and production level.
The risk related to this practice is that ancient olives might be considered only as ornamental plants and therefore, the farming, productive and environmental conditions in Apulia and Greece might be seriously affected due to:
Figure 2 – The main threats to the Mediterranean ancient olives.