Traditions of tree planting vary. Some societies see no need to plant any trees, others plant a few for fruit, shade or poles, a few others have elaborate agro-forestry systems, making effective use of many species. However, in nearly all societies, native peoples know a great deal about trees and their properties, as demonstrated by the many detailed ethnobotanical studies.
Olive groves are Europe's oldest farmed habitat, with many trees in Italy dating back five or six centuries and some being a thousand years old. Olive trees thrive in conditions of low rainfall, with long dry summers and mild winters, where the natural vegetation comprises Mediterranean scrubland with holm and cork oaks.