Application de la Géomatique au Suivi de la Dynamique de Système Agro-Sylvo-Pastoral : Cas de la Région de Ben Badis, Constantine, Algérie.

Abstract – Monitoring changes in land use and land use is becoming increasingly important in the analysis of terrestrial ecosystem dynamics. In this context, the natural and social environment in Algeria has been strongly modified by population growth and climatic hazards in recent decades. This results in changes in land use and a noticeable change in natural vegetation. Remote sensing images are widely used to map land cover and analyze the spatio-temporal dynamics of Agro-Sylvo-Pastoral systems. The present study evaluates Agro-Sylvo-Pastoral System changes between 2001 and 2016, through a directed classification of satellite images, in the region of Ben Badis, Constantine, Algeria. The results show a change in the natural area with a significant decrease in the area covered by grasslands by 44.35% for crops, and growth of artificial areas by 230%. This study has just shown, on the one hand, the potential of the use of remote sensing and geographical information system (GIS) to analyze spatio-temporal dynamics, from a series of satellite images, D ' on the other hand, the identification and characterization of Agro-Sylvo-Pastoral System changes in order to guide the decisions of the concerned actors towards a better management of the environment.

Keywords: Agro-Sylvo-Pastoral, Geomatics, Land cover, GIS, Constantine.

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Les facteurs responsables du dépérissement de la subéraie de la Kroumirie (Nord Ouest de la Tunisie).

 
Abstract -  Observations during the period (2002-2017) were achieved in different cork oak forest according to altitude, exposures, masked and unmasked trees, burned, not burned, and mutilated. This study focused on the whole Tunisian cork oak forest. The various visits of the exploitation cork sites showed that the decline of the cork oak forests is the direct result of the bad cutting cork, capping and mutilation, repeated fires, xylophagous insects, fungal diseases, and water stress. All these factors act simultaneously from the first infestation to the inevitable decline of the tree. Observations and follow-ups of the stations studied made the following conclusions: 

- Defective removal associated with mutilations predisposes the tree to a progressive physiological weakening;

- Xylophagous insects and fungal diseases take advantage of this weakening to colonize the tree in a critical situation;

- The analysis of rainfall distribution, in the study area, has highlighted the existence of a deficit annual water balance ranging from 5 to 6 months (from April to September in the sub-region of Tabarka and 5 months in the hives of Ain Draham and El Feija).

-Avoiding at all costs the dismantling of decline trees, diseased, limbed, mutilated or recently burned;

- Hire only skilled and experienced workers in cork harvesting;

- Use appropriate cork harvesting equipment;

- Re-examine the rotation and the weeding coefficients, which vary according to the fertility of the stations;

- Apply silvicultural treatments according to stages of development to prevent competition between cork producing trees.

Keywords: Cork oak forests, oak pests, decline, Kroumirie

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Abstract - Cork quality mainly depends on caliber and visual aspects and is manually classified into  grades (9 classes according to IPROCOR). The main purpose of this study was to investigate the effects of variability both between sites and intra-tree, as well as the interaction between these factors, on cork caliber, some physical properties and cork quality, characterized mainly by caliber and the presence of some visual defects. A total of 240 trees were sampled at six sites in northwestern Tunisia. From each tree, two cork planks were sampled at ~ 0 m and 1.3 m tree height. Cork caliber (median: 59 mm), as well as density (240.1 kg/m³)did not seem to vary significantly with the site, but it did seem to vary with tree sampling height; the farther up the tree the thinner and less dense was the cork. Cork quality index ( ), at cork plank level, was treated as an ordinal rating scale  (9 grades), based on cork commercial price, and analyzed using a rank-based nonparametric method.  varied significantly only according to site. For convenience, cork quality grade could be reduced to five classes (Stopper quality; Thick; Thin; Poorquality; and Discarded cork). Discarded cork had the highest percentage rate (50%), followed by Stopper quality (24%) and Poorquality (21%) once. Both Thick and Thin classes had percentage rates of only 2% and 4%, respectively, and were therefore merged with Stopper and Poorquality classes, respectively. A simple cork quality classification limited to three classes (bad, medium and good quality) was then defined.As for Cork quality index, this variable was significantly dependent on site, but not on tree sampling height, and couldalso be used to study cork quality based onenvironmental factors. Permanent plots should be installed to better understand environmental factors influencing cork quality.

Keywords: Quercus suber L.; cork; cork caliber; cork defects; northwestern Tunisia; Generalized Linear Mixed Models.

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Diversité de la flore lichénique épiphyte des formations à chêne kermès (Quercus coccifera) du littoral d'El Kala (extrême Nord-Est algérien)

Abstract - The study of the lichenic flora on Quercus coccifera carried out in the region of El Kala which is in the extreme Northeast Algeria proved very interesting. More than 50 lichens were recorded represented by two types of photobionts; green algae andTrentepohlia. The systematic spectrum indicates that the listed lichens belong to 14 families, the most important of which are the Parmeliaceae and the Physciaceae. The physiognomic spectrum notes the presence of only 3 lichenic categories: crustaceans, foliaceae and fruit. The total wealth quantified by type of vegetation stage mentions the importance of the lichens of the thermomediterranean stage with 50%. The ecological index relating to the phytogeographical aspect indicates that the lichenic flora of the phorophyte studied consists of two main chorotypes; the temperate and the suboceanic.

Keywords: Lichens, phorophyte, Quercus coccifera, El Kala, Algeria.

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Effet de la récurrence des incendies sur l’abondance et la distribution de la faune du sol sous Quercus suber L. dans la forêt de Taksebt Zekri (Algérie)

Abstract - An ecosystem's biological diversity is a good indicator of its quality and ability to withstand deterioration due to external factors. However, the protection of biodiversity is a key element of the preservation of the environment. The objective of this work is to evaluate the impact of recurring fires on the abundance and distribution of soil macrofauna, under Quercus suber L., in the Taksebt forest, Zekri north of Algeria. Macroinvertebrates were collected from six adult cork oak trees at four depths using the Coineau method in December 2016. We counted 2912 individuals in 18 orders. Seasonal and climatic conditions inhibit the development and growth of living organisms, limiting their abundance and controlling their vertical distribution. Some of these invertebrates flee the surface conditions and penetrate deeply by seeking the most suitable conditions for their survival. The disruption of this natural ecosystem by recurring fires also induces changes in the physical and chemical properties of soils, which influences the distribution of invertebrate populations and their diversity. The composition of the fauna of these soils is an indicator of its physical, chemical and biological quality, it must be taken into consideration for its rehabilitation. This study has made it possible to prioritize the factors that control the abundance of invertebrates and to provide reference values ​​in the kosheria.

Keywords: Quercus suber L., ground, macro fauna, depth, fire.

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Evolution spatiotemporelle des feux de forêt dans le Nord-est algérien : cas de la wilaya d’El Tarf

Abstract - In Algeria, more than 30,000 hectares of forest are destroyed by fire every year. Economic losses due to these wildfires between 1985 and 2006 exceed 113 billion Algerian dinars (more than a billion USD today). In order to understand and monitor the spatiotemporal evolution of wildfires, this study aims at modelling, mapping, and analysing all the wildfire ignitions recorded in the forest tracts of the Algerian province of El Tarf between 1985 and 2012. In order to achieve this goal, a geographical database relating to the forest tracts under study was compiled, then used to perform a number of analyses and geospatial processing. Between 1985 and 2012, 3259 wildfire ignitions were recorded in El Tarf, destroying 61,671 ha of forest tracts, thus averaging 18.92 ha per single wildfire. Expressed in yearly averages, there were 2202.52 ha of burnt land in 116.39 distinct wildfires per year over the period under study. The geographical database produced in the course of this research could be a very useful tool for forest managers in establishing wildfire typologies and mapping wildfire risks.

Keywords: Statistics, Spatial distribution, Wildfire ignitions, Cartography, GIS.

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