Rainfall patterns of Algerian steppes and the impacts on natural vegetation in the 20^th century  

作　　者：Fahima BELALA Azziz HIRCHE Serge D MULLER Mahmoud TOURKI Mostefa SALAMANI Mohamed GRANDI TaharAIT HAMOUDA Madjid BOUGHANI 

机构地区：[1]Laboratory of Plant Ecology,Faculty of Biological Sciences,University of Sciences and Technology Houari Boumediene,Wilaya 16000,Algeria [2]Scientific and Technical Research Center on Arid Regions,Biskra 7000,Algeria [3]Institute of Evolutionary Sciences,University of Montpellier-CNRS,Montpellier 34095,France [4]Department of Hydraulics,University of Badji Mokhtar,Annaba 23000,Algeria [5]Faculty of Nature Sciences,University of Saad Dahlab,Blida 9000,Algeria [6]Faculty of Sciences,University of Yahia Fares,Wilaya 26000,Algeria

出　　处：《Journal of Arid Land》2018年第4期561-573,共13页干旱区科学（英文版）

基　　金：funded by the Ministère de l'Enseignement Supérieur et de la Recherche Scientifique of Algeria

摘　　要：Since 1960, the steppe regions of North Africa have been subject to an increasing desertification, including the degradation of traditional pastures. The initially dominant species （Artemisia herba-alba, Lygeum spartum and Slipa tenacissima） declined and were progressively replaced by other species （Atractylis serratuloides and Salsola vermiculata） that are more tolerant to the new conditions. It is not clear whether these changes are due to anthropogenic reasons or climatic determinism. We have carried out a statistical analysis of the climate to detect putative rainfall changes during the 20th century in the Algerian steppes based on data from 9 meteorological stations, including 2 Saharan stations （El Oued and Touggourt）, 3 pre-Saharan stations （Biskra, Laghouat and Ain Sefra） and 4 steppe stations （Djelfa, Saida, M6ch6ria and E1-Bayadh） located in the arid high plains, which represent the bioclimate diversities of the region. Previous studies suggested that significant rainfall changes for the 20th century only had records in the south of the Oran region. Most of the studies, however, looked at restricted territories over limited periods, and did not integrate the rainiest period 2004-2014. Our work is designed to integrate all the longest time series of meteorological data available for the steppe regions of Algeria. Our results confirm the spatial rainfall distribution （significant rainfall changes only recorded in the southwestern region） evidenced by previous studies, and reveal a decreasing rainfall gradient from northeastern to southwestern Algeria. Moreover, the results reveal a trend of significant decrease of rainfall in the southern Oran region, marked by two drought periods in 1980- 1985 and 1999-2003. However, with the exception of the southwestern region, rainfall overall has not declined since the beginning of the 20th century. While less marked in other regions, the drought appear to have affected all territories of the Algerian steppe. Consequently, our study implies thSince 1960, the steppe regions of North Africa have been subject to an increasing desertification, including the degradation of traditional pastures. The initially dominant species （Artemisia herba-alba, Lygeum spartum and Slipa tenacissima） declined and were progressively replaced by other species （Atractylis serratuloides and Salsola vermiculata） that are more tolerant to the new conditions. It is not clear whether these changes are due to anthropogenic reasons or climatic determinism. We have carried out a statistical analysis of the climate to detect putative rainfall changes during the 20th century in the Algerian steppes based on data from 9 meteorological stations, including 2 Saharan stations （El Oued and Touggourt）, 3 pre-Saharan stations （Biskra, Laghouat and Ain Sefra） and 4 steppe stations （Djelfa, Saida, M6ch6ria and E1-Bayadh） located in the arid high plains, which represent the bioclimate diversities of the region. Previous studies suggested that significant rainfall changes for the 20th century only had records in the south of the Oran region. Most of the studies, however, looked at restricted territories over limited periods, and did not integrate the rainiest period 2004-2014. Our work is designed to integrate all the longest time series of meteorological data available for the steppe regions of Algeria. Our results confirm the spatial rainfall distribution （significant rainfall changes only recorded in the southwestern region） evidenced by previous studies, and reveal a decreasing rainfall gradient from northeastern to southwestern Algeria. Moreover, the results reveal a trend of significant decrease of rainfall in the southern Oran region, marked by two drought periods in 1980- 1985 and 1999-2003. However, with the exception of the southwestern region, rainfall overall has not declined since the beginning of the 20th century. While less marked in other regions, the drought appear to have affected all territories of the Algerian steppe. Consequently, our study implies th

关 键 词：CLIMATE arid and semi-arid regions DROUGHT rangeland degradation human impact North Africa 

分 类 号：S812[农业科学—草业科学] S731.2[农业科学—畜牧学]