Strengths of existing land use practices
As it was mentioned the main land use types in the area study areas of Crete are olive groves, vineyards, citrus plantations, avocado, vegetables, and pastures. The olive originated in the Eastern Mediterranean area, and has been cultivated by man since ancient times. Trees are extremely long-lived (up to 1000 years) and tolerant to drought, and salinity. Olive oil was used for cooking as well as burning in lamps; several references are made to olive oil lamps in the Bible and other ancient writings.
Olives are supremely adapted to Mediterranean climates. They cannot tolerate high humidity which causes disease and physiological disorders. Temperature may approach -15°C in midwinter, but foliage is damaged by frost only during active growth. The chilling requirement is relatively high given the cold hardiness and distribution - 1000 hr. Some texts refer to the cold requirement as "vernalization", since reproductive structures develop during the cold period. This is a rather moot point since the length of exposure to cool temperatures is the same regardless of the true physiological process.
Olives are grown on a wide variety of soils, many too poor to support cultivation of other crops. They are tolerant of high pH, salinity, excess of boron, and drought, but are sensitive to flooding. In Greece olives are frequently used as garden trees. They have attractive, silver-green evergreen foliage, full canopies, requiring very little water and disease control. Since the Minoan period, olives have been harvested by hand, knocking them from the trees and collecting them from the ground. This technique requires a lot of manpower and causes contamination of the fruits. Small harvesting machines have been developed recently significantly reducing both labour and time between harvesting and the oil extraction process.
Olives present a particularly high adaptation and resistance to long term droughts and support a remarkable diversity of flora and fauna even higher than some natural ecosystems. Olive groves can be considered as a natural forest highly adapted in dry Mediterranean conditions, with lower vulnerability to fires as compared to pine forests, protecting hilly areas from desertification. Olive groves are widely expanded in hilly areas, with semi-arid climatic conditions, very sensitive to desertification. Olives protect the soil sufficiently from raindrop impact restricting soil erosion. Furthermore, olives plantations require minimum cultivation efforts except for the period of harvesting offering a significant income to the farmer. The following management practices are required for good production:
- Pruning for rejuvenation or fruit production at the harvesting period
- Proper fertilization mainly by nitrogen or phosphate fertilizers
- Weed control by mechanical cultivation or herbicides applied once per year, early in spring for conserving soil water and facilitating harvesting.
- Complementary irrigation applied in areas with low rainfall or in years with limited rain, particularly during spring
- Control of Dacus or other pests and diseases is of great importance for both the yield and quality.
Cultivation of vineyards started around 25th century BC. Several varieties are described by Aristotle, Theophrastus, and Isiodos, while many stories are related to vines and their products in the ancient period. Wine has always been appreciated in Cretans, so vineyards are today cultivated in every place where climatic conditions are favourable, in combination with other domestic crops, supporting the family income. Vine cultivation has declined in more recent decades due to infection by phylloxera and other diseases. New plantations, more resistance to phylloxera, have been planted in Crete.
Pastures are widely expanded in Crete with great ecological and economical importance for the production of low cost and good quality of animal products. Even though pastures present serious problems related to the land productivity and the environment, they contribute significantly in the economy of the Crete.
