Fuel resources for copper smelting in antiquity in selected woodlands in the Edom highlands to the Wadi Arabah/Jordan

Abstract

Summary Near Feinan, in the area between the Wadi Arabah and the highlands of Edom, an analysis of the standing biomass was carried out on remnants of the woody vegetation used as fuel for copper smelting since the Early Bronze Age. The analysis provides biomass data for individual shrubs and trees as well as for one hectare. For the first time the amount of wood available from seven types of shrub- and woodlands is discussed in relation to different species spectra obtained from charcoal remains of five copper smelting periods. The preliminary quantitative data presented here provide the botanical basis for an interdisciplinary approach which relates human impact to the degradation of woodlands. For sixteen shrubs and trees from eight species the individual amount of wood was determined. Up to eight diameter categories, including fine twigs, were defined in order to obtain data on all the wood used as fuel. The highest amount of wood was found to be Tamarix jordanis with nearly 800 kg dried wood per plant. Medium sized trees of Acacia spp., Juniperus phoenicea, Pistacia atlantica and Quercus calliprinos yield approximately 150 to 500 kg wood. The dry weight of a typical Retama raetam or Haloxylon persicum shrub is 2 to 15 kg. For seven species, representative squares with pure stands up to one hectare were chosen, and releves were taken. The number of plants per hectare was counted as multiples of the individuals defined as typical for the species in that region. From these data, the amount of wood per hectare was calculated. The data can be interpreted as the maximum amount of wood available for fuel in each vegetation unit. Riparian thickets of Tamarix jordan is with 135 t dried wood per hectare were found to be the vegetation the most rich in energy. Also rather rich in wood are evergreen Juniperus phoenicea and sclerophyllous Quercus calliprinos woodlands. Rather little wood per hectare is produced by Haloxylon persicum and Acacia spp. open vegetation. While further physical and chemical properties of the woods are not yet known, dry density is discussed as a possible criterion for the selection of a particular wood as fuel. The dry density of wood of Olea europaea, Acacia cf. tortilis and Haloxylon persicum is nearly 1.0 g/cm 3 , that of Rhamnus spp. and Lycium shawii even 1.1 g/cm 3 . Pistacia atlantica, Quercus calliprinos and Retama raetam wood has a dry density of about 0.9 g/cm 3 . Juniperus phoenicea and Tamarix jordanis have 0.8 and 0.7 g/cm 3 , respectively. Moringa peregrina has only 0.4 g/cm 3 . Finally, archaeobotanical aspects of this work are pointed out. The use of vegetation by man in antiquity is discussed. The dominance of the highland species Juniperus phoenicea in charcoal spectra from the Bronze Age and its absence in later times is interpreted as indication of a climatically induced temporary depression of its area. On the basis of archaeological evidence, transportation as well as overexploitation can be excluded as explanations for this decline during Bronze age. On the other hand the total destruction of Tamarix stands near Feinan due to overexploitation during Iron Age and Persian Period is highly probable.