Interactions of land use, climate and soil development in the context of settlement history in the Decapolis-Region (Northern Jordan)
Final Report Abstract
It was assumed that historic desertification in northern Jordan was connected with severe degradation of soils, and caused by agricultural mismanagement and deforestation. This idea served as explanation for historic developments like decay and abandonment of cities, and is basis of current projects to mitigate the impact of global warming. However, soil erosion in the investigation region occurred largely at the end of the last Ice Age and during the Younger Dryas. The project found no indication that the inanimate landscape changed significantly during historical periods, and all investigated areas are characterised by sufficient, fertile soil cover - frequently with intact remains of historic field systems. The investigation of soil thin sections with a Scanning Electron Microscope yielded evidence that isovolumetric replacement plays a role for the formation of Terra Rossa in Jordan, but its precise interaction with Aeolian deposition, clay illuviation, and dissolution of the bedrock could not yet be quantified. Red soil colour in Jordan appears to be a relic from periods of intense soil-formation during the Pleistocene, possibly connected with heavy dust thunderstorms as Indicated by quartz grain microsurfaces. Pedogenic manganese oxides extracted with dithionite were surprisingly well suited to characterise soil development intensities, while the evaluation of pedogenic Iron oxides with dithionite suffered from iron in pnmary carbonates which was extracted as well. The magnetic susceptibility proved very valuable for the Interpretation of soil development Intensities and might be suited as proxy for past vegetation densities. Historic field systems were partially preserved and seem reflected by distinct soil development, indicating that the impact of land use was more complex and less devastating than previously assumed. Historical human impact on the natural environment seems limited and certainly not connected with desertification. The comparative analysis of soils and colluvia, air photos, historic travel reports, tree rings and climate reconstructions indicates that population growth was behind the ancient flourishing of the region, which took place mostly under favourable climatic conditions. Periods of decline seem triggered by climatic anomalies. As it seems, climate change was previously understood too linearly. Extreme rainfall events can be more devastating than drought, and temperature, wind and rainfall distribution over the year are important as well. Climatic fluctuations dunng history may have been connected with pests, famines, plagues and wars which caused dramatic drops of population. Especially the end of the Byzantine period seems characterized by fast and very significant landscape changes, expressed by the deposition of mudflows and rubble slides, creating huge valley fills which buried the Byzantine land use installations in depressions. These events were connected with heavy flooding, probably due to a more frequent or intense occurrence of heavy precipitation events, and possibly connected with earthquakes. Similar periods of instability might have occurred during the "Yarmoukian landslides", and possibly at the end of the Early Bronze Age and during the Mamluk-Ottoman period. Northern Jordan is ecologically sensitive which aggravates the Impact of climate variations. It is so far unknown how climate will develop under global warming, but it seems very likely that an increasing number of anomalous events would have dramatic impacts on current societies. A systematic combination of different climate archives with soil and land use studies would offer a way fonward to better understand and predict the dynamics of landscape changes under climate change.
Publications
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2006. The Decapolis region (Northern Jordan) as historical example of desertification? Evidence from soil development and distribution. Quaternary International 151, Special Issue I, Dark nature: responses of humans and ecosystems to rapid environmental changes, 74-86
Schmidt, M., Lucke, B., Bäumler, R., al-Saad, Z., al-Qudah, B., Hutcheon, A.
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2006. The Past as a Key for the Future: Mutual Dependencies of Land Use, Soil Development, Climate and Settlement. In: Shouval, H., Dweik, H. (eds.), Water for Life In the Middle East, al-Jerashi press, Jerusalem, Vol. 1, 403-420
al-Saad, Z., Lucke, B., Schmidt, M., Bäumler, R.
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2006. Water Systems of the Decapolis (Northern Jordan) and their Relation to the Landscape during the Hellenistic and Roman Periods. Pres-actes, colloque International: La gestion Integree de l'eau dans l'histoire environnementale - savoirs traditionnels et pratiques modernes, Universite Laval, Quebec, Canada, 27.-29.10.2006, 275-279
Lucke, B., Schmidt, M., al-Saad, Z., Bäumler, R.
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2007. Landscape Transformation in the Decapolis Region (Northern Jordan) - A Critical Re-examination of a Paradigm. In: Ooghe, B., Verhoeven, G. (eds.). Broadening Horizons, Multidisciplinary Approaches to Landscape Study, Cambridge Scholars Publishing, Newcastle, 30-49
Lucke, B., Bäumler, R., Schmidt, M., al-Saad, Z.
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2007. Past and Present Desertification in the Context of Climate Change - a Case Study from Jordan. Forum der Forschung, BTU Cottbus, 85-88
Lucke, B., Schmidt, M.
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2007. Soils and Paleosols at Ba'ja. Neo-Lithics 02/07, 43-50
Lucke, B., Bäumler, R.
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2007. Village Life in Mamluk and Ottoman Hubras and Saham: Northern Jordan Project-Report on the 2006 Season. Annuals of the Department of Antiquities of Jordan 52, 429-470
Walker, B., Kenney, E., Holzweg, L., Caroll, L., Boulogne, S., Lucke, B.
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2008 Demise of the Decapolis. Past and Present Desertification in the Context of Soil Development, Land Use, and Climate. Verlag Dr. Mueller, Saarbrücken
Lucke, B.
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2008. Soil substrate classification and the FAO and World Reference Base systems: examples from Yemen and Jordan. European Journal of Soil Science 59, 824-834
Pietsch, D., Lucke, B.
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2008. Soils and Land Use in the Decapolis Region (Northern Jordan). Implications for Landscape Development and the Impact of Climate Change. Zeitschrift des Deutschen Palästina-Vereins (ZDPV) 124/2,171-188
Lucke, B., al-Saad, Z., Schmidt, M., Bäumler, R., Lorenz, S.-O., Udluft, P., Heußner, K.-U., Walker, B.
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2008. The impact of drought in the light of changing soil properties. In: Sanchez, J. (ed.). Droughts: Causes, Effects, and Predictions, Nova Science Publishers, NewYork, 69-102
Lucke, B., Nikolskii, I., Schmidt, M., Bäumler, R., Nowaczyk, N., al-Saad, Z.
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2008. Wasser oder Boden - welches war der Schlüssel für die Blüte der Dekapolis-Region? Cura Aquarum in Jordanien, Schriften der DWhG Band 12,177-188
Lucke, B.
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2008. Water Systems of the Decapolis (Northern Jordan) and their Relation to the Landscape dunng the Hellenistic and Roman Periods. In: E. Hermon (ed.), L'eau comme patrimoine. De la Mediterranee ä TAmerique du Nord. Quebec, Collection "Patrimoine en mouvement". Presses de l'Universite Laval, 223-236
Lucke, B., Schmidt, M., al-Saad, Z., Bäumler, R.
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2009. Desertification in Jordan in the Light of Paleosols and Past Environmental Change. In: Gabriels, D., Cornells, W., Eyietters, M., Hollebosch, P. (eds.), Combating Desertification. Assessment, Adaptation and Mitigation Strategies, UNESCO Chair of Eremology and Belgian Development Cooperation, Ghent, 64-73
Lucke, B., Schmidt, M., Bäumler, R.
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2010. Progressive Development and Strategic Environmental Assessment (part III of the book, several sub-chapters). In: Issar, A. (ed.), Progressive Development: To mitigate the negative impact of global warming on the semi arid regions. Springer, Heidelberg, 89-137
Lucke, B., Nikolskii, I., Helbron, H., Palekov, D.
