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标题：Diachronic analysis of land cover in the Gabi District (Maradi region, Niger) and characteristics of vegetation
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作者：Ali Mahamane ; Saadou Mahamane ; Bakasso Yacoubou 等
期刊名称：Science et changements planétaires / Sécheresse
印刷版ISSN：1147-7806
电子版ISSN：1777-5922
出版年度：2007
卷号：18
期号：4
页码：296-304
DOI：10.1684/sec.2007.0105
出版社：John Libbey Eurotext
摘要：Figures See all figures Authors Ali Mahamane , Saadou Mahamane , Bakasso Yacoubou , Abassa Issaka , Aboubacar Ichaou , Karim Saley Département de biologie, Faculté des sciences, Université Abdou Moumouni, BP 10662, Niamey Niger, Laboratoire de botanique systématique et phytosociologie, Université libre de Bruxelles (ULB), CP 169, 50, avenue Franklin Delano Roosevelt, B-1050 Bruxelles Belgique, Ministère de l’Hydraulique, de l’Environnement et de la Lutte contre la Désertification, BP 578, Niamey Niger, Institut national de la recherche agronomique du Niger (Inran), BP429, Niamey Niger Key words: agroforestry, deforestation, diachronic study, floristic composition, forest species, Niger, land use, satellite imaging and geomatics, vegetation DOI : 10.1684/sec.2007.0105 Page(s) : 296-304 Published in: 2007 The District of Gabi is located in the Maradi region in the southern central region of the Niger Republic. It covers a surface of 79,052 ha and comprises the principal land reserves and forests of this region. The aims of this work are to analyze the general evolution of land use in the District and to characterize its main particularities affecting the present structure of plant communities. This analysis of land use dynamics requires the interpretation of aerial photographs from 1972 brought up to date by satellite datum from 2005. The study shows the deep transformations that have occurred over the past 31 years in connection with the natural dynamics of the vegetation. This diachronic analysis shows a projection of the same agricultural activities which have resulted in a reduction of the tree savannah/shrub savannah from 31,822 ha in 1972 to 15,667 ha in 2005, a reduction of 20%, accompanied by an extension of the agricultural zones which has passed from 1,690 hectare to 9,042 hectares in 2005, an increase of 9%. The topography and the availabily of hydrological resources play an important role in plant community dynamics. Large diameter individuals are thus found mainly in the lower areas where there is a good hydrological state. After this comparative review of the agricultural mechanism of colonization of the tree savannah/shrub savannah, we show the importance of the relationship between vegetation and current environmental risks and the need to produce new indicators for the use of the forest. This study made it possible to characterize the initial situation and to identify the questions which will be deepened by investigations within the framework of the device of long-term monitoring according to the Roselt (Réseau d’observatoires de surveillance écologique à long terme, Long Term Ecological Monitoring Observatories Network) methodology.
关键词：agroforestry; deforestation; diachronic study; floristic composition; forest species; Niger; land use; satellite imaging and geomatics; vegetation