Environmental Changes in Lebanon During the Holocene: Man Vs
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ARTICLE IN PRESS Journal of Arid Environments xxx (2009) 1–10 Contents lists available at ScienceDirect Journal of Arid Environments journal homepage: www.elsevier.com/locate/jaridenv Environmental changes in Lebanon during the Holocene: Man vs. climate impacts L. Hajar a,*, M. Haı¨dar-Boustani b, C. Khater c, R. Cheddadi a a Universite´ Montpellier 2, CNRS, Institut des Sciences de l’Evolution CC 061, Place Euge`ne Bataillon, 34095 Montpellier Cedex 05, France b Muse´e de Pre´histoire libanaise, Universite´ Saint-Joseph de Beyrouth, Lebanon c Center for Remote Sensing, National Council for Scientific Research in Lebanon, BP 11-8281, Bir Hassan, Beirut, Lebanon article info abstract Article history: Pollen and archaeological studies were undertaken in the Southern Bekaa Valley (Lebanon, Mediterra- Received 25 April 2008 nean region). Two Holocene records retrieved in the Aammiq and Chamsine/Anjar wetlands, respectively Received in revised form located at the foothills of Mount Lebanon and Anti-Lebanon Mountain, in the Southern Bekaa Valley, 12 November 2008 were analyzed to highlight climatic vs. anthropogenic influence on landscape patterns. Our data records Accepted 13 November 2008 support hypothesis on climatically driven modification during the Late Glacial Age and the early Holo- Available online xxx cene. Human disturbances in the study area are only depicted after c. 8 ky cal. BP, with different patterns in eastern and western parts of the Southern Bekaa Valley. These modifications are in line with major Keywords: Deforestation landscape changes in the Eastern Mediterranean region. Since c. 8 ky cal. BP, major deforestation events Human impact on Mount Lebanon are recorded in the Aammiq area depicting human interference, while in Chamsine/ Levant Anjar, no sign of such activities can be interpolated since strong deciduous oak development is recorded. Neolithic sites Archaeological records from the same region confirm human impact on the forest during the Neolithic Pollen period. Numerous bifacial flint tools, such as axes, adzes, and chisels, manufactured in the prehistoric workshops of the Southern Bekaa Valley, attest to the beginning of the deforestation during this period. From c. 3.5 to c. 2 ky cal. BP, deforestation seems reduced on Mount Lebanon while in the Chamsine/ Anjar area oak forest expansion is still recorded. During the same period, grazing activities were per- formed in the Bekaa Valley. Between c. 2 and c. 1 ky cal. BP, and on both sites, deforestation and grazing practices are inferred from pollen records. No cultivated plants are recorded in this region. In this view, these Holocene data illustrate important differences in patterns of human activity in comparison with other areas located in the Eastern Mediterranean, where cultivated olive trees and forests decline are well identified. From c. 1 ky cal. BP into the modern period, increasing human perturbations affected the pollen record on both sites. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction the observed variations. Few years later, Ruddiman (2003) devel- oped a new hypothesis, which affirms that ‘‘pre-industrial forest The human impact on the environment is an object of interest in clearance in Eurasia since c. 8 ky cal. BP explains the rise in the our days. The CO2 increase in the atmosphere and its effects as concentration of atmospheric CO2 between c. 8 ky cal. BP and c. greenhouse gas are studied from different aspects aiming to 1.8 ky AD.’’ In fact, cultivated plants are recorded in the Fertile understand how and when these changes occurred. The concen- Crescent since the beginning of the Neolithic1 on several archaeo- 2 tration of CO2 in the atmosphere has increased drastically and logical sites (Colledge et al., 2004; Twiss, 2007). During the PPNB, steadily since the pre-industrial era (Crutzen and Stoermer, 2000), plant cultivations are identifiable in several parts of the Fertile a phenomenon which inevitably leads to global warming and Crescent (Appendix 1, electronic version only). After the PPNB, strong climate variability (IPCC, 2007). But what if human beings domesticated cereals and animals are encountered in several sites had an impact on climate much earlier than the last two centuries? from the Eastern Mediterranean. These archaeological reconstruc- Indermu¨ hle et al. (1999) shows an increase of atmospheric CO2 tions are reinforced by palaeobotanical studies where the main concentration since c. 8 ky cal. BP and suggests that terrestrial biomass and sea surface temperature were largely responsible for 1 c. 11.5–c. 8.5 ky cal. BP (after Aurenche et al., 1981). 2 Pre-Pottery Neolithic B – period initially defined by Kenyon (1956, 1960) on the * Corresponding author. Tel.: þ33 (0) 467143925; fax: þ33 (0) 467144044. stratigraphic subdivisions at Jericho (Israel), between c. 10.7 and c. 9 ky cal. BP (after E-mail address: [email protected] (L. Hajar). Aurenche et al., 1981). 0140-1963/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jaridenv.2008.11.002 Please cite this article in press as: Hajar, L., et al., Environmental changes in Lebanon during the Holocene: Man vs. climate impacts, Journal of Arid Environments (2009), doi:10.1016/j.jaridenv.2008.11.002 ARTICLE IN PRESS 2 L. Hajar et al. / Journal of Arid Environments xxx (2009) 1–10 cultivated plants and deforestation were recorded (Appendix 1). In 3. Material and methods the Fertile Crescent, pollen records from Israel (Baruch, 1990; Schwab et al., 2004) show olive cultures and oak deforestation 3.1. Palynological data since c. 6 ky cal. BP. In Syria (Niklewski and van Zeist, 1970; Yasuda et al., 2000), olive cultures are also recorded but problems of dating Two cores were extracted, using a Russian corer, in the prevent the arriving to any conclusions about the beginning of such Aammiq wetland (33460N, 35460E, 865 m, 5.40 m long) and in human events (Meadows, 2005). the Chamsine/Anjar wetland (33440N, 35570E, 856 m, 3.10 m Palaeobotanical studies dealing with the impact of man on long) (Fig. 1). Nine AMS 14C dates were made on sediments palaeoenvironments were carried out throughout the Fertile (Table 1, nomenclature follows Troels-Smith, 1955). Four AMS 14C Crescent (Yasuda et al., 2000; Schwab et al., 2004; Neumann dates have been obtained on the Aammiq core and five AMS 14C et al., 2007). However, there is a gap in our knowledge about dates on the Chamsine/Anjar core (Table 1)(Fig. 2). Earlier studies palaeoenvironments of the Holocene in Lebanon, a critical have shown potential problems related to the hard water effect region for understanding the expansion of agricultural societies and contamination when dating sediments (Olsson, 1973, 1983). in the Near East. In an attempt to provide additional information Hard water effect usually provides older dates when dating on past vegetation dynamics over the Eastern Mediterranean sediments (Olsson, 1983). Consequently, the absence of mis- region and assess the importance of human activity regarding matching between our palynological results in Lebanon and landscape changes, this paper presents a comparative approach others regional palynological studies in Israel and Syria permits between palaeobotanical data (two Holocene pollen records) to dismiss problems of date aging. Moreover, the age/depth and archaeological data (eight Neolithic sites) in the Southern models performed using a linear interpolation between the Bekaa Valley. radiocarbon dates (Fig. 2) seem to be reliable. Carbon dates have been calibrated with the CALIB 5.0 program (Stuiver and Reimer, 2. Study area 1993) with the calibration curve Intcal04 (Reimer et al., 2004). The confidence interval between the minimum and maximum The Aammiq and Chamsine/Anjar wetlands are situated in the calibrated dates at 2s (Table 1) corresponds to the time interval Southern Bekaa Valley between Mount Lebanon and Anti-Lebanon shown in Fig. 2. Mountain (Fig. 1). Pollen analyses with a w200-year intervals were carried out The Bekaa is considered one of the most important agricultural (Figs. 3 and 4) at the Universite´ Montpellier 2, CNRS, Institut des zones in Lebanon, producing 57% of the vegetables, 37% of the fruit Sciences de l’Evolution (ISEM, France). trees, and 62% of the industrial cultures of the country. The beetroot The extraction of pollen grains followed standard methods is one of the most important industrial crops produced in the (Faegri and Iversen, 1989) including cold HCl digestion to remove Bekaa, followed by potato, cereals, and grains. Grapes are also carbonates, hot KOH to remove soluble humic acids and cold HF to considered an important production of the Bekaa Valley with remove silicates. Finally, fluo-silicates were eliminated using cold almost 0.067 km2 of vineyards (Ministe`re de l’Agriculture/FAO, HCl. The residue is mixed with a known volume of glycerin in order 2005). to mount the slides for the pollen count under the optical micro- Pastoralism in Lebanon, and especially in the Bekaa, is still scope using a 60 magnification for pollen recognition. More than considered a major source of activity as 67% of total livestock in 300 pollen grains per sample were counted excluding aquatics, Lebanon are present in the Bekaa (31% of bovine and 36% of ovine) swamp, and damaged pollen grains – with the exception of (Ministe`re de l’Agriculture/FAO, 2005). particularly poor samples. As they dominate the local landscape, all The vegetation of Lebanon is described by Abi-Saleh (1978).On aquatic plants and Cyperaceae were excluded from the total pollen the eastern slope of Mount Lebanon around the Aammiq wetland, sum. three vegetation levels are present. Between 800 and 1000 m Two types of oaks were identified: Quercus cerris-type which (Eumediterranean level), Mount Lebanon is covered mainly by includes pollen grains of Q. brantii, Q. cedrorum, Q. cerris, Q. infec- Quercus calliprinos formation with scattered trees and degraded toria, Q.