INTRODUCTION

Vegetation in the Mediterranean basin has been formed for millennia alongside human activities, as a result of the same land surface being used for human needs and demands for multiple uses. Because vegetation and landscapes are part of the daily life of those exploiting them, they include special systems, called agroforestry systems that host many plant species, which are sometimes rare and important for the purposes of conservation and exploitation.

Semi-natural hedges usually they do not "constitute" agroforestry systems, but participate in combination with pastures and agricultural land

Shrubland Agroforestry Systems

Shrublands are perhaps the most interesting Mediterranean landscape to have been co-shaped by humans, directly related to grazing and firewood collection and constituting the most common agroforestry landscape in Greece.

Most of these shrublands are dominated by evergreen broad-leaved species, mainly by the kermes oak (Quercus coccifera), lentisc (Pistacia lentiscus) and strawberry tree (Arbutus unedo), spreading almost across the Mediterranean zone (Dafis et al. 2001).

The broad-leaved evergreen shrubs (Figure 1), especially the kermes oak stands, were the main areas for goat grazing. They also provided valuable firewood and due to their great resistance to grazing, managed to survive and reduce soil erosion in mountainous and semi-mountainous areas. In areas where they were converted to crops, parts of them remained at the edges of agricultural land, acting as conservation zones for important species of flora and fauna. Agroforestry systems can also include carob (Ceratonia siliqua) - olive (Olea europaea) shrublands; due to degradation from intense past management or recent abandonment, today these are mainly carob or olive grazing crops, where important plants adapted to highly xerothermic conditions survive (Caballero et al. 2009, Ispikoudis et al. 2021).

In less dry areas in Central and Northern Greece, the semi-natural hedges (Figure 2) are composed of deciduous species (e.g. Jerusalem thorn – Paliurus spina-christii, European field elm – Ulmus minor, U. procera, bramble – Rubus spp.), constituting the “silbjak” or, as the locals call them, “tsalia” or “lumakia” formations. Semi-natural hedgerows do not usually ‘constitute’ agroforestry systems, but participate in them in conjunction with pastures and agricultural crops. “Tsakna”, meaning the thin wood for tinder, as well as larger firewood, were collected from the seminatural hedges. At the same time, a large number of woody species of hedgerows were used for grafting, such as the almond-leaved pear (Pyrus spinosa) and for their edible fruits, such as the blackthorn (Prunus spinosa) and the Cornelian cherry (Cornus mas). Individual large trees were a resting place for farmers, herders and animals during the hot hours of the day (Ispikoudis et al. 2021). The flora composition of these systems mainly includes nitrophilous and synanthropic species that are favored by fertilizers and the presence of many farm animals in small or larger areas. Nevertheless, due to the strong heterogeneity in structure and the special conditions of the places where they grow (at the borders of agricultural land, in small spots where water is collected and nutrients are deposited), they have a particularly high plant diversity with many annual species (Fotiadis 2004).

The oak forests are the meeting place of wood and livestock products