Scientifically based biodiversity management in timber concessions: contribution to conservation and sustainable use of biodiversity

During the past 25 years, forest laws in Central African countries have undergone major changes. Management plans were made mandatory: nearly 19 million hectares of timber concessions (38% of total granted concessions) were subject to a management plan in 2013 and the dynamics is currently underway. The management plan is based on a set of technical and scientific studies, including statistical surveys (management inventories) covering the whole concession and taking into account all timber species, large mammals and the main non timber forest products. These inventories allow, at concession level, to characterize ecosystems and to assess the forest conservation values, through floristic and faunal biodiversity indicators and by taking into account threats to the forest ecosystems, especially anthropogenic ones. Such management inventories are used especially for planning and forecasting harvests, while minimising environmental impacts on the forest structure and functioning, and retaining regeneration capacities of the timber species and the forest ecosystems. The knowledge gained on specific and ecosystemic biodiversity helps to define management rules to ensure the sustainability of different timber species' populations, noticeably the exploited ones. It is also used to design areas within the concessions were exploitation will not take place due to conservation interest (most biodiversity-rich areas, protection of rare or endangered species...). Such so-called “conservation series” therefore complement the protected areas network. Well-managed forest concessions can help conserve the regional forest ecosystems and maintain essential functions that they provide. However, management plans were up to now designed at the concession scale. Data acquired in forest concessions also significantly contribute to improve knowledge of the forest ecosystems and their functioning at the regional level. Using this data, the CoForChange Project (http://www.coforchange.eu) issued a map of the forest ecosystems developed in the "Sangha River Interval" region. This project suggested that those forest ecosystems could react differently to disturbance, and could need an adaptation of management methods to each ecosystem. Based on forest inventories, other initiatives are underway to map the forest types and the biomass stock at the scale of Central Africa, and might be of particular interest for policy decisions on forest ecosystems. (Texte intégral

Towards an EDSL to enhance good modelling practice for non-linear stochastic discrete dynamical models Application to plant growth models

International audienceA computational formalism is presented that structures a C++ library which aims at the modelling, simulation and statistical analysis of stochastic non-linear discrete dynamical system models. Applications concern the development and analysis of general plant growth models

The forests of the Congo Basin : State of the forest 2010

The 2010 State of the Forest report (SOF) benefited from financial support from the European Union, the United States, Germany, France and UNESCO. It represents the collaborative effort of over 100 individuals from a diversity of institutions and the forestry administrations of the Central African countries. The SOF process began with the selection and definition of indicators relevant to monitoring the state of forests in Central Africa. The indicators are structured around three thematic areas: (i) forest cover; (ii) management of production forests; and (iii) conservation and biodiversity. They are presented in a hierarchical structure at the regional, national and management unit (i.e. logging concessions and protected areas) levels. The indicators were vetted by a representative panel of stakeholders of forest management in Central Africa. The indicators are used to guide an annual data collection process carried out between April and August by national groups of four to ten individuals working within the forestry administrations. The data reported on in the 2010 SOF were primarily collected in 2009 and 2010. Results were validated in national workshops attended by government officials as well as representatives of environmental NGOs, the private sector and development projects. The data provided an important basis for the authors of the 11 chapters of the 2010 SOF, which were under the coordination of a scientific committee of international renown. A final workshop was held 29-30 March, 2011 in Douala to review a draft report. Following amendments based on comments from a wide audience of experts the final layout was completed. (Résumé d'auteur

Ultrasound of the coracoclavicular ligaments in the acute phase of an acromioclavicular disjonction: Comparison of radiographic, ultrasound and MRI findings.

OBJECTIVES: Acromioclavicular joint injuries are typically diagnosed by clinical and radiographic assessment with the Rockwood classification, which is crucial for treatment planning. The purpose of this study was to describe how the ultrasound findings of acromioclavicular joint injury compare with radiography and MRI findings. METHODS: Forty-seven patients with suspected unilateral acromioclavicular joint injury after acute trauma were enrolled in this prospective study. All patients underwent digital radiography, ultrasound and 3T MRI. A modified Rockwood classification was used to evaluate the coracoclavicular ligaments. The classifications of acromioclavicular joint injuries diagnosed with radiography, ultrasound and MRI were compared. MRI was used as the gold standard. RESULTS: The agreement between the ultrasound and MRI findings was very good, with a correlation coefficient of 0.83 (95 % CI: 0.72-0.90; p < 0.0001). Ultrasound detected coracoclavicular ligament injuries with a sensitivity of 88.9 %, specificity of 90.0 %, positive predictive value of 92.3 % and negative predictive value of 85.7 %. The agreement between the ultrasound and radiography findings was poor, with a correlation coefficient of 0.69 (95 % CI: 0.51-0.82; p < 0.0001). CONCLUSION: Ultrasound is an effective examination for the diagnostic work-up of lesions of the coracoclavicular ligaments in the acute phase of an acromioclavicular injury. KEY POINTS: • Ultrasound is appropriate for acute acromioclavicular trauma due to its accessibility. • Ultrasound contributes to the diagnostic work-up of acute lesions of the coracoclavicular ligaments. • Ultrasound is appropriate in patients likely to benefit from surgical treatment. • Ultrasound could be a supplement to standard radiography in acute acromioclavicular trauma

Filtrage par noyaux de convolution itératif

International audienceL'estimation paramétrique des modèles dynamiques en biologie est souvent rendue complexe par les fortes interactions entre processus et les non-linéarités qui en découlent, ainsi que par la difficulté de l'observation du système par expérimentation. C'est en particulier le cas des modèles de croissance de plantes. Dans cet article nous étudions l'application de la méthode de filtrage particulaire par convolution, développée pour permettre d'estimer les paramètres et les états cachés simultanément pour des systèmes non-linéaires. Nous proposons une variation de cette méthode mettant en jeu des itérations multiples du filtre particulaire par convolution, en tenant compte des informations obtenues lors de l'itération précédente afin d'améliorer l'estimation des paramètres. Une version conditionnelle de l'approche est également proposée dans le cas d'un système dynamique bruité, en réalisant l'estimation paramètres-états en supposant les paramètres du modèle de bruits connus, puis en estimant ces derniers grâce aux états cachés estimés, et en relançant l'algorithme avec ces nouveaux paramètres. La méthode a été implémentée pour un modèle de croissance de betterave avec observations rares, et les résultats apparaissent meilleurs que la méthode de filtrage par convolution sans itération, même réalisée avec un nombre bien plus important de particules. La méthode est par ailleurs générique, robuste et facilement adaptable

Modeling forest biomass of the Congo basin from extensive commercial inventories

Mapping the vegetation Carbon stocks is crucial to understand the global climate change. The Carbon stock maps have direct implications in economy and environmental policy. This is especially true in tropical forests where most of the uncertainties on carbon fluxes and stocks are concentrated. Substantial efforts have been done recently to map forest carbon in tropical areas, especially by using remote sensing-based approaches. However, there is no way to bypass a calibration step where biomass is locally measured through forest inventories. The great importance of this learning step and its possible issues has been documented, highlighting the importance of terrestrial datasets. In our work, we have gathered a very large dataset of forest inventories covering the Congo Basin. It consists of 73 000 0.5ha plots of commercial inventories covering 4 million hectares in Cameroon, Republic of Congo, Gabon, Central African Republic, and the Democratic Republic of the Congo. These terrestrial data are of great value to understand and model the spatial distribution of various forest properties, among which the Carbon stock. They can also make a great tool to control and improve the performance of the remote sensing methods. In our study, we rely on these plots to test the validity of previously published pantropical Carbon maps. After gathering the data with extra care due to the heterogeneous inventory methods, we used bioclimatic models, topography, and remote sensing observation to extrapolate the forest carbon estimates at the Congo basin scale. (Texte intégral