INTRODUCTION

Silvoarable agroforestry systems, which combine the presence of trees and agricultural crops on the same land, are one of the three types of agroforestry systems found in Greece, the other two being silvopastoral and agrosilvopastoral systems. The vegetation of these systems is very rich and consists of various species and functional types. Overstory trees exist in dynamic equilibrium with understory shrubs and herbaceous plants (Papanastasis, 2004). There are several types of agroforestry systems characterized by the trees of the overstory. Depending on the management practice they can be distinguished into traditional and new silvoarable systems. In traditional systems, the trees of the overstory are native, remnants of older forest areas, and past management lasting until last few years has not caused any disturbance to the individual parts of the system. The new ones include systems where the trees were specifically planted for their fruits or for their timber, while at the same time the understory is used to produce agricultural crops in order to achieve a better use of the space.

The ecological value of traditional agroforestry systems refers to the preservation of its mosaic landscape and biodiversity, as they include a large number of species and individuals of both plants and animals. These systems are more stable than any form of conventional agriculture in terms of protecting the soil, improving the environment, habitats and wildlife, ensuring the stability and functionality of ecosystems, but also preserving or improving the country’s landscapes (Ispikoudis et al. 1996). Economically, agroforestry systems provide a wide variety of products and services. The various trees of the overstory produce timber, firewood, stakes and fruits. Wood of various species, such as walnut, is valuable for furniture, while poplar is used for paper production. The foliage and acorns of oaks are used as food for animals, while the fruits of walnut, chestnut, and various other fruit trees (apples, pears, almonds, olives, etc.) are used as food for humans. Along with trees, understory agricultural crops provide a steady annual income to farmers.