Unique human-made catenary changes and their effect on soil and vegetation in the semi-arid Mediterranean zone: a case study on Sarcopoterium spinosum distribution near Tell eṡ-Ṡâfi/Gath, Israel

Abstract

The semi-arid Mediterranean landscape in the area of Tell eṡ-Ṡâfi (biblical Gath of the Philistines), in central Israel, has been affected by extraordinary human activities. The Judean foothills in the region are characterised by chalk and calcrete with a patchy cover of Rendzina soils. Unique human-made geomorphic and catenary changes in the landscape, nearly 3000 years ago, left their marks on the vegetation distribution in the area today. A very large trench that surrounds the tell on three sides was excavated in the Iron Age II (ca. 9th century B.C.E.). The trench served as a siege moat, part of an offensive siege system around the tell. The trench is 2.5 km long, 8–10 m wide, and has a maximum depth of 5.5 m. A berm, consisting of dumped earth and rock fragments excavated from the trench, is situated alongside the entire length of the trench, covering the original surface. Our catenary landscape analysis revealed that a particular vegetation species, Sarcopoterium spinosum, is dominant on the berm, covering 78% of its surface area. Its coverage of the three other catenary landscape units, slope above the berm, trench, slope below the trench, is only 29%, 32% and 24%, respectively. Bedrock exposure in the berm is less than 4%, which together with the slightly elevated position of the berm results in surface area conditions of relatively low water retention. Such areas are conducive to S. spinosum establishment and survival, due to the plant's high resistance to comparatively dry conditions. Thus, the human landscape changes almost three thousand years ago caused a dramatic catenary change that continues to have a distinct effect on vegetation distribution today.