Long-term monitoring of Gray-leaved Sagebrush (Artemisia herba-alba Asso.) steppe in southern Oran Region (Algeria): factors and indicators of change

Les steppes d’Armoise blanche (Artemisia herba-alba Asso.) dans le Sud-Oranais constituent des parcours de grand intérêt pastoral. La dynamique à long terme de ces steppes a été étudiée sur une période d’une quarantaine d’années par un suivi diachronique (i) en site permanent en considérant 5 années de référence et (ii) dans 30 stations échantillonnées dans le reste de la steppe d’armoise en 1975-76 et en 2013-2015. Les résultats montrent globalement une dégradation qui s’est accompagnée de changements dans la composition et la dominance des communautés avec l’apparition ou l’extension d’espèces indicatrices de changements d’usage et de conditions écologiques. L’augmentation des éphémères peut expliquer l’augmentation de la diversité béta, alors que parallèlement, la diversité gamma a baissé, accompagnée d’une banalisation de la flore. Par rapport au reste de la steppe préexistante d’armoise, dans le site de surveillance, la fixation du sable suite à une série d’années pluvieuses aurait joué un rôle important dans la régénération du couvert végétalThe Gray-leaved Sagebrush (Artemisia herba-Alba Asso.) steppes in the Southern Oran region in Algeria are rangelands of great pastoral interest. 40 years long-term dynamics of these steppes has been studied since 1975 using a diachronic monitoring (i) in permanent site considering five reference years and (ii) in 30 sites in the rest of the sagebrush steppe in 1975-76 and 2013-2015. Results generally show degradation with changes in the community composition and species dominance with appearance or extension of indicator species reflecting changes in land-use and environmental conditions. The increase in ephemeral species may explain the increase in the beta diversity, while the gamma diversity decreased underlying a trend toward banalization of the plant community composition. Unlike the rest of the pre-existing sagebrush steppe, in the monitoring site, following a series of rainy years, sand which had been fixed would have played an important role in the recovery of the vegetation cove

Forty years monitoring in an Algeria alfa steppe in southern Oran Region (Algeria): plant diversity and composition changes

La perte de diversité végétale, en tant que révélateur de la dégradation des parcours arides steppiques, est l’une des grandes préoccupations pour les pays du sud de la Méditerranée. Ces steppes sont confrontées à deux forces motrices majeures inter-agissantes : le climat aride avec des sécheresses récurrentes de durée et d’intensité variables d’une part et le surpâturage de l’autre. La surveillance à long terme des changements dans la diversité floristique et la composition des communautés végétales est considérée comme le meilleur moyen de comprendre l’histoire et les mécanismes de la dégradation des écosystèmes et de la désertification. Partant de la communauté préexistante, dans laquelle l’Alfa (Stipa tenacissima) était la dominante et la clé de voûte de l’écosystème quant à sa structure et son fonctionnement, une surveillance de quarante ans a permis d’analyser les changements de richesse floristique, de diversité et de composition de la communauté avant qu’elle n’atteigne son état actuel de steppe dégradée et appauvrie.The loss of plant diversity as a degradation feature in arid steppic rangelands is one of the crucial concerns in the southern Mediterranean countries. These rangelands are facing two interacting driving forces: the arid climate with recurring and more or less lasting droughts on the one hand, and overgrazing on the other. Long-term monitoring of change in diversity and composition of plant communities is considered to be the best way to understand the history and mechanisms of ecosystem degradation and desertification. Starting from a pre-existing community in which alfa (Stipa tenacissima L.) was the dominant and the keystone species regarding ecosystem structure and functioning, forty years monitoring allowed analysing changes in floristic richness, diversity and community composition prior attaining its current state of degraded and impoverished steppe

The functional assessment procedures CD-Rom.

Functional assessment enables the user to predict the functioning of a wetland area without the need for comprehensive and expensive empirical research The FAPs therefore provide a methodology that can be used by both experts and non-experts to assess wetland functioning relatively rapidly. The volume includes an electronic version of the FAPs on CD which automates aspects of the assessment once the initial recording stage is completed. It is anticipated that the FAPs will be used by a range of individuals or organisations concerned with wetland management who wish to gain a better understanding of the processes, functions, services or benefits and potential of the wetlands for which they have responsibility

La surveillance à long terme en réseau circum-saharien : l'expérience ROSELT

ISBN : 978-9973-856-33-3The long term ecological surveillance observatoires network (Réseau d'Observatoires de Surveillance Ecologique à Long Terme, ROSELT/OSS) of the Sahara and Sahel Observatory (OSS) consists of a cluster of observatories which span circum-Saharan Africa and share a common focus on the issue of desertification. Since its inception, the network has been addressing the challenge of improving the collective knowledge on desertification; a scourge that has complex linkages with the issues of biodiversity and climate change. Over the last ten years, OSS has put in place standardised protocols of data collection and processing in the circum-Sahara with a view to apprehending the trends characterising the evolution of the ROSELT/OSS observatories' ecological and socio-economic systems. In this part of Africa, where rainfall decrease is chronic in the Sahel and spreading to North Africa, population growth and land use change—due to overgrazing or the conversion of rangelands into croplands—have adverse impacts on the environment. In addition, sand encroachment constitutes a serious threat to irrigated farmland. Biodiversity is equally affected, as several species face the danger of extinction due to human activities. In the south of the Sahara, natural resource depletion is often among the causes for migration towards the zones where climate and life conditions are more favourable. This forced displacement is significantly less severe in the north of the Sahara where policies put in place by governments in the sub-region encourage sedentary lifestyles. Based on the scientific reports of the ROSELT/OSS observatories, this publication provides an overview of the data management systems and the decision-support tools developed across the ROSELT/OSS network. It also highlights difficulties pertaining to environmental surveillance in North and West Africa

The Thero-Brachypodietea communities under extinction threat at there southern arid margins

International audienc

Exclosure as restoration technique for degraded arid rangelands (steppic high-plains of Algeria)

International audienc

Réponse des écosystèmes steppiques arides à la sécheresse à différentes échelles temporelles

International audienc

La surveillance à long terme en réseau circum-saharien : l'expérience ROSELT

ISBN : 978-9973-856-33-3The long term ecological surveillance observatoires network (Réseau d'Observatoires de Surveillance Ecologique à Long Terme, ROSELT/OSS) of the Sahara and Sahel Observatory (OSS) consists of a cluster of observatories which span circum-Saharan Africa and share a common focus on the issue of desertification. Since its inception, the network has been addressing the challenge of improving the collective knowledge on desertification; a scourge that has complex linkages with the issues of biodiversity and climate change. Over the last ten years, OSS has put in place standardised protocols of data collection and processing in the circum-Sahara with a view to apprehending the trends characterising the evolution of the ROSELT/OSS observatories' ecological and socio-economic systems. In this part of Africa, where rainfall decrease is chronic in the Sahel and spreading to North Africa, population growth and land use change—due to overgrazing or the conversion of rangelands into croplands—have adverse impacts on the environment. In addition, sand encroachment constitutes a serious threat to irrigated farmland. Biodiversity is equally affected, as several species face the danger of extinction due to human activities. In the south of the Sahara, natural resource depletion is often among the causes for migration towards the zones where climate and life conditions are more favourable. This forced displacement is significantly less severe in the north of the Sahara where policies put in place by governments in the sub-region encourage sedentary lifestyles. Based on the scientific reports of the ROSELT/OSS observatories, this publication provides an overview of the data management systems and the decision-support tools developed across the ROSELT/OSS network. It also highlights difficulties pertaining to environmental surveillance in North and West Africa