Agricultural systems and terrace pattern distribution and preservation along climatic gradient: From sub-humid mediterranean to arid conditions

Agricultural terraces are a well-distributed agrotechnical method around the world. The current review aims to provide a holistic analysis of agricultural terrace spatial distribution along a climatic gradient of sub-humid Mediterranean, semi-arid and arid climate zones. It focuses on the relationship between geographic conditions and spatial distribution only, and does not examine chronological establishment or use. Three case studies that were carried out in the Land of Israel are presented and explored according to their geographic occurrence. In the Judean Mountains (central Israel), under sub-humid Mediterranean conditions, agricultural terraces are characterised by terrace coverage on slopes and in valleys. Annual rainfall average in this region is between 500 and 700 mm, allowing for vast rain-fed agriculture based on direct rain. In the Southern Shephelah (the Judean foothills, central Israel), a region under semi-arid conditions, agriculture terraces are located in small spots on the slopes, and in terrace fields in the valleys. Annual average rainfall in this region is between 300 and 400 mm. Rain-fed agriculture was sustained by direct rain and additional runoff generated on rock outcrops. In the Negev Highlands (southern Israel), a region under arid climate conditions with annual rainfall average of 100 mm, runoff farm terraces are located in valleys, and agriculture sustenance was based on water harvesting from the slopes. The terrace pattern distribution is similar to the natural vegetation pattern distribution of the three given areas. For the past several dozen years, changes in land use methods have resulted in the abandonment of many agricultural terraces in these areas. Terrace abandonment leads to the collapse of retaining walls and erosion of soil and sediments from the terrace body, with the latter occurring at a high rate in the arid Negev highlands. However, in the Judean Mountains and the Judean Shephelah, areas under sub-humid Mediterranean and semiarid conditions, the intensity of erosion is lower since the terraces are covered by dense shrubs such as Sarcopoterium spinosum, which stabilizes and moderates soil and sediment erosion. This regional difference shows that the absence of maintenance is more significant in arid areas. To conclude, there are two primary insights 1: Climate has a dominant effect on agricultural terrace distribution, and ancient farmers knew how to adapt to different climate conditions. 2: Climate conditions have a major effect on terrace preservation and maintenance.