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Rivers are hotspots for biological diversity and sources of ecosystem services. After centuries of degradations, river restoration has been recognized as essential to reestablish their socio-ecological quality. This research aims (1) to identify the different restoration practices and drivers, and examine the particularities of urban river restorations, and (2) to assess the potential conflicts inside the socio-ecological system. It concludes, that the better consideration of the socio-ecological system should allow the maximum benefit for both humans and the environment., Die Flussrenaturierung wurde zur Wiederherstellung der sozio-ökologischen Qualität der Flüsse erkannt. Diese Studie hat sich zum Ziel gesetzt unterschiedliche Renaturierungspraktiken und deren Triebkräfte zu identifizieren, die Besonderheiten städtischer Flussrenaturierungen zu untersuchen und die potenziellen Interessenskonflikte im sozio-ökologischen System zu bewerten. Eine wichtige Schlussfolgerung ist, dass eine verbesserte Einbeziehung des sozio-ökologischen Systems, zu besseren Ergebnisse führen könnte, und dadurch der Nutzen für Mensch und Ökologie maximiert wird.

Rivers are hotspots for biological diversity and sources of ecosystem services. After centuries of degradations, river restoration has been recognized as essential to reestablish their socio-ecological quality. This research aims (1) to identify the different restoration practices and drivers, and examine the particularities of urban river restorations, and (2) to assess the potential conflicts inside the socio-ecological system. It concludes, that the better consideration of the socio-ecological system should allow the maximum benefit for both humans and the environment., Die Flussrenaturierung wurde zur Wiederherstellung der sozio-ökologischen Qualität der Flüsse erkannt. Diese Studie hat sich zum Ziel gesetzt unterschiedliche Renaturierungspraktiken und deren Triebkräfte zu identifizieren, die Besonderheiten städtischer Flussrenaturierungen zu untersuchen und die potenziellen Interessenskonflikte im sozio-ökologischen System zu bewerten. Eine wichtige Schlussfolgerung ist, dass eine verbesserte Einbeziehung des sozio-ökologischen Systems, zu besseren Ergebnisse führen könnte, und dadurch der Nutzen für Mensch und Ökologie maximiert wird.

The present study aims to review palaeoecological evidence for environmental changes induced by human activities over the last few millennia in the montane landscapes of Morocco. The study is based on well-dated pollen and geochemical records from the Rif and the Middle Atlas mountains, to show spatial and temporal variation in the onset and intensity of exploitation of forest, soil and mineral resources. Before ca. 2000 BP, anthropogenic impact was minimal. At about that time, abrupt changes of the arboreal pollen proportions, with a decline in all tree taxa, indicate a reduction of the forest cover interpreted as being anthropogenic. In the Rif Mountains, increased influx of carbonates (Ca) in the sedimentary records indicates enhanced soil erosion coincident with the reduction in tree cover. In the Middle Atlas, reduced forest cover is linked to geochemical evidence for mining and metallurgy of lead (Pb), copper (Cu) and zinc (Zn). These industrial activities correspond to the expansion of the Roman Empire into Morocco at around AD 40 and show a decline when the Romans were displaced by the Vandals about five centuries later.

Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.

La coupure que l'on constate dans les forêts denses africaines au niveau du Togo et du Bénin soulève de nombreuses questions sur les rapports forêt/savane au cours des derniers millénaires. Le projet Dahomey Gap vise à y répondre, par une approche pluridisciplinaire intégrant botanique et histoire de la végétation dans le Sud-Bénin et le Sud-Ouest du Nigéria. A partir de travaux déjà avancés sur la végétation du Bénin et des premières prospections palynologiques, quelques aspects du projet sont exposés ici: tels la caractérisation des différentes formations forestières du Bénin, les premiers résultats sur l'histoire holocène de la végétation du Sud-Bénin (mangroves, forêts, savanes) enregistrée depuis près de 7000 ans dans les lagunes.

La coupure que l'on constate dans les forêts denses africaines au niveau du Togo et du Bénin soulève de nombreuses questions sur les rapports forêt/savane au cours des derniers millénaires. Le projet Dahomey Gap vise à y répondre, par une approche pluridisciplinaire intégrant botanique et histoire de la végétation dans le Sud-Bénin et le Sud-Ouest du Nigéria. A partir de travaux déjà avancés sur la végétation du Bénin et des premières prospections palynologiques, quelques aspects du projet sont exposés ici: tels la caractérisation des différentes formations forestières du Bénin, les premiers résultats sur l'histoire holocène de la végétation du Sud-Bénin (mangroves, forêts, savanes) enregistrée depuis près de 7000 ans dans les lagunes.