In the Central Rif in the north of Morocco, forest ecosystems have suffered a very sharp decline in favor of crops. Deforestation followed by cultivation illustrates the important environmental, economic and social roles of forests. The objective of this work is to assess the impact of deforestation on soil properties and erosion in the southern Central Rif. The loss of fertility of cleared soils was assessed using physico-chemical analyses after 2, 8 and 20 years of cultivation. A manual rainfall simulation was used to assess the impact of cultivation on the hydrodynamic behavior of the soil. The results show that the conversion of forests into agricultural areas has multiple consequences on the natural system. The general trend of soil texture elements after cultivation shows a significant increase in sand content, and a decrease in clay and silt content. Soil erodibility measured by USLE-K factor increased 3.5 times in the cultivated soil for 20 yrs. compared to the forest soil. Subsequent tillage of cultivated land increases bulk density and fragments large aggregates into smaller ones. Cultivation for 8 and 20 yr decreased SOM by 41 and 82% respectively. Total Nitrogen decreased by 45%, acidity increased by 0.8 unit after 20 years of cultivation. Conversion of natural forest to agricultural land significantly increases soil erosion. The erosion rate becomes higher in the cultivated the 8 and 20 yr cultivation, with an average of 219.60 ± 19.3 and 989.17 ± 68.4 g m-2 h-1 respectively. This degradation hinders agricultural productivity, leading farmers to abandon the land and seek new plots at the expense of forests to meet their agricultural land needs.

Apport de la télédétection et du SIG au suivi de la dynamique spatiotemporelle des forêts dans le massif numidien de Jbel RESUMÉLes écosystèmes forestiers du massif numidien de Jbel Outka situé au coeur du Rif Central au nord du Maroc, ont connu, au cours des dernières décennies, de grandes pressions aussi bien naturelles qu'anthropiques conduisant à des changements observables dans le paysage forestier. Néanmoins la nature et l'intensité de ces changements restent peu connues. L'objectif de cette étude est d'évaluer la dynamique du paysage forestier du massif numidien de Jbel d'Outka, et d'en expliquer les causes, en se basant sur une approche GOT, n.º 11 -Revista de Geografia e Ordenamento do Território (junho de 2017) GOT, nr. 11 -Geography and Spatial Planning Journal (June 2017) 172 diachronique repose sur l'intégration et traitement des données multidates et multisources, à l'aide du Système d'Information Géographique (SIG), et des logiciels de la Télédétection spatiale. Les résultats obtenus soulignent une forte régression dans les dynamiques de la forêt.Mots clé : Photographie aérienne ; images satellitaires ; télédétection ; SIG ; milieu forestier ; Jbel Oudka ; Rif Central . RESUMOOs ecossistemas do maciço florestal númido da montanha Outka localizam-se no Rif Central no norte de Marrocos e têm, nas últimas décadas, altas pressões naturais e antropogénicas, levando a alterações observáveis na paisagem florestal. A natureza e a intensidade destas mudanças permanecem pouco conhecidas. O objetivo deste estudo é avaliar a dinâmica da paisagem florestal do maciço Outka da montanha Outka e explicar as suas causas, com base numa abordagem diacrónica, usando a integração e processamento de dados multidate e multi-fonte, usando GPS e software de sensoriamento remoto do espaço. Os resultados obtidos mostram uma forte regressão na dinâmica da floresta.Palavras-chave: Fotografia aérea; Imagens de satélite; Sensoriamento remoto; SIG, floresta de montanha Outka; Montanha de Rif central ABSTRACTThe forest ecosystems of the Numidian massif of Outka mountain are located in the Central Rif in northern Morocco, and have got, over the past decades, high natural and anthropogenic pressures, leading to observable changes in the forest landscape. The nature and the intensity of these changes remain little known. The objective of this study is to assess the dynamics of the forest landscape of the Outka massif of Outka mountain, and explain their causes, based on a diachronic approach, using the integration and processing of multidate and multisource data, Using GPS and Space Remote Sensing software. The results obtained show a strong regression in the dynamics of the forest.