Legacy of logging roads in the Congo Basin: how persistent are the scars in forest cover?

Logging roads in the Congo Basin are often associated with forest degradation through fragmentation and access for other land uses. However, in concessions managed for timber production, secondary roads are usually closed after exploitation and are expected to disappear subsequently. Little is known about the effectiveness of this prescription and the factors affecting vegetation recovery rate on abandoned logging roads. In a novel approach we assessed logging roads as temporary elements in the forest landscape that vary in persistence depending on environmental conditions. We analyzed road persistence during the period 1986–2013 in adjacent parts of Cameroon, Central African Republic and Republic of Congo. Three successive phases of road recovery were identified on LANDSAT images: open roads with bare soil, roads in the process of revegetation after abandonment and disappeared roads no longer distinguishable from the surrounding forest. Field based inventories confirmed significant differences between all three categories in density and richness of woody species and cover of dominant herbs. We used dead-end road segments, built for timber exploitation, as sampling units. Only 6% of them were identified as being re-opened. Survival analyses showed median persistence of four years for open roads before changing to the revegetating state and 20 years for revegetating roads before disappearance. Persistence of revegetating roads was 25% longer on geologically poor substrates which might result from slower forest recovery in areas with lower levels of soil nutrient content. We highlight the contrast amongst forests growing on different types of substrate in their potential for ecosystem recovery over time after roads have been abandoned. Forest management plans need to take these constraints into account. Logging activities should be concentrated on the existing road network and sites of low soil resource levels should be spared from business-as-usual exploitation. (Résumé d'auteur

Characterization of the aquifers of the Bangui urban area, Central African Republic, as an alternative drinking water supply resource

This paper presents the results of a survey carried out in 2010 aimed at evaluating the type and quality of the groundwater resources of the Bangui region of the Central African Republic. This work is the first step towards the development of groundwater resources in the Central African Republic in order to find alternatives to direct pumping from the Ubangi River and provide the population of the suburbs with a safer drinking water supply from deep boreholes. By combining both geological and hydrogeochemical approaches, it appears that the geology of Bangui is favourable to the development of a secure and sustainable water supply from groundwater provided that the conditions of exploitation would be constrained by the local authorities. The deep Precambrian carbonate aquifers, known as the Bimbo and Fatima formations, are identified as target resources in view of the relatively good quality of their water from the chemical point of view, and the semi-confined structure of the aquifers that prevents the mixing with shallow aquifers that are already strongly affected by domestic and industrial pollution. The main difficulty in terms of exploitation is to appreciate the depth of the resource and the more or less fractured/palaeo-karstified type of the porosity

Espaço, poder e escravidão no De Re Rustica de Columela

Este artigo analisa a configuração do espaço e a organização do trabalho escravo na propriedade rural (uilla) descrita por Columela em seu tratado De Re Rustica, tendo como hipótese que ambos os aspectos não são regidos por critérios exclusivamente econômicos, como a historiografia geralmente entende, mas sobretudo políticos, uma vez que remetem ao entendimento que Columela tinha da política romana na época do principado de Nero.<br>This article examines the space configuration and the organization of slave work in the rural property (uilla) as described by Columela in his treaty De Re Rustica. The related hypothesis is that both aspects are not solely governed by financial criteria, as historiography usually perceives, but also political, given it refers to Columela´s understanding of Roman politics during Nero's principality

Pollen-plant-climate relationships in sub-Saharan Africa

International audienc

The conservation significance of the proposed Mbaere-Bodingue national park, Central African Republic, with special emphasis on its primate community

WOS:000227153600015International audienceThe proposed Mbaere-Bodingue National Park ( 872 km(2)) is located in the southwestern part of the Central African Republic and consists of terra firma rain forests and seasonally flooded forests. We assessed the conservation significance of this site using data on wildlife and habitat conditions collected during a comprehensive primate survey. Scores were attributed to a system of variables and sub-variables to assess the conservation value of the proposed park at the national level. We identified a total of 10 diurnal primate species ( eight monkeys, two apes) and flooded forests were considered as a key habitat for primates as they hold a greater number of species than terra firma forests. We recorded the presence of 12 mammal species listed under the 2000 IUCN Red List of Threatened Species, including four classified as Endangered ( two Primates, one Proboscidae and one Insectivora). We found that the conservation value of the proposed park ranked second out of the 15 existing protected areas of the country. Primate abundance was found to be generally higher than in the nearby Dzanga-Ndoki National Park ( the sole other park located in the same vegetation unit), in particular for the species occurring in flooded forests. This highlights the fact that the proposed Mbaere-Bodingue National Park is an important area for the conservation of species associated with flooded forests, a habitat which is currently underrepresented in the national protected area system. Poaching pressure was identified as the main current threat to the integrity of the proposed park