Cartographie numérique des habitats de reproduction de l’avifaune nicheuse du lac Tonga, parc national d’El-Kala (Nord Est Algérien)

Les prospections et observations réalisées en 2007 en période estivale, sur les habitats naturels et l’avifaune aquatique nicheuse du lac Tonga (Parc National d’ El-Kala), ont permis d’identifier 16 habitats de reproduction dans lesquels nous avons obtenus 6923 contacts de 19 espèces d’oiseaux d’eau nicheuses. La plus forte densité en oiseaux nicheurs a été observée au niveau du secteur Nord-Est du lac Tonga. Les habitats les plus utilisés sont représentés par la scirpaie, le rubanaie et la typhaie. L’espèce la plus abondante, est le Grèbe castagneux (Tachybaptus rufficollis), avec 1574 contacts. La cartographie numérique des habitats naturels du lac Tonga a permis de mieux cerner la relation « habitats de reproduction – avifaune nicheuse ». L’approche cartographique utilisée dans cette étude, a confirmé l’importance des SIG dans la gestion des ressources naturelles.The investigations and observations done during summer season in 2007 for natural habitats and breeding water birds at the Tonga Lake (National park of El-Kala), have permitted to identify 16 natural reproductions habitats, in which we have got 6923 contacts of 19 various species of water birds. The most important density of breeding water birds is located in the North East of the lake. The habitats which are most used by the breeding water birds at Tonga lake are the “Scirpaie, the Rubaniae, and the Typhaie”. The most important specie of water birds is a Tachybaptus rufficollis, with 1574 contacts. The numerical cartography of natural reproduction habitats, have permitted to have a better understanding of the relationship between reproduction habitats – breeding water birds at Tonga Lake. The cartography simulation used in this study, has confirmed that the GIS, is important in the management of the natural resources

Détection des changements au niveau d’un couvert forestier en milieu semi-aride entre 1984–2009: Cas de la forêt de Senalba Chergui de Djelfa (Algérie)

The main objective of this work was to detect changes in a semi-arid forest using Landsat satellite multi-temporal imagery and to circumvent the lack of data on landscape temporal changes. The differential-algebraic method (subtraction) was used on 12 remote sensing variables obtained at different fixed periods. Before applying the differentiations on remote sensing data, a geometric correction and a radiometric normalization of satellite images were carried out to allow images comparison. Differentiation of individual bands (TM4 and TM5), ratios (TM4/TM5 and TM7/TM5), indexes (NDVI and NDMI), Tasseled Cap differentiation (e.g. TCB [Brightness], TCG [Greenness] and TCW [Wetness]) and finally the differentiation of the first three ACPs (ACP1, APC2 and ACP3) were carried out in order to select the best data for the detection of changes. Many radiometric thresholds were tested (11 values) to identify which ones had the ability to determine the best changes in the different studied periods. The most significant values of global precision (GP) (greater than 72% for the four studied periods) obtained in the error matrices were those of the NDVI variable using 0.9δ (δ = standard deviation) at the mean. This allowed the calculation of NDVI changes and the positive, negative and stable proportions for each period. The use of recent very high resolution spatial images for validation allowed us to highlight the causes of changes and the impact of silvicultural works during the period of forest management