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Olagoke A.,TU Dresden | Olagoke A.,Institute Des Science Et Industries Du Vivant Et Of Lenvironnement Agroparistech | Feret J.-B.,500 rue J.F. Breton | Fromard F.,Ecolab | And 4 more authors.
Trees - Structure and Function | Year: 2015

Key message: We estimated aboveground biomass of large mangrove trees from terrestrial Lidar measurements. This makes the first attempt to extend mangrove biomass equations validity range to trunk diameter reaching 125 cm.Abstract: Accurately determining biomass of large trees is crucial for reliable biomass analyses in most tropical forests, but most allometric models calibration are deficient in large trees data. This issue is a major concern for high-biomass mangrove forests, especially when their role in the ecosystem carbon storage is considered. As an alternative to the fastidious cutting and weighing measurement approach, we explored a non-destructive terrestrial laser scanning approach to estimate the aboveground biomass of large mangroves (diameters reaching up to 125 cm). Because of buttresses in large trees, we propose a pixel-based analysis of the composite 2D flattened images, obtained from the successive thin segments of stem point-cloud data to estimate wood volume. Branches were considered as successive best-fitted primitive of conical frustums. The product of wood volume and height-decreasing wood density yielded biomass estimates. This approach was tested on 36 A. germinans trees in French Guiana, considering available biomass models from the same region as references. Our biomass estimates reached ca. 90 % accuracy and a correlation of 0.99 with reference biomass values. Based on the results, new tree biomass model, which had R2 of 0.99 and RSE of 87.6 kg of dry matter. This terrestrial LiDAR-based approach allows the estimates of large tree biomass to be tractable, and opens new opportunities to improve biomass estimates of tall mangroves. The method could also be tested and applied to other tree species. © 2015 Springer-Verlag Berlin Heidelberg

Sauleau P.,Rennes University Hospital Center | Sauleau P.,University of Rennes 1 | Despatin J.,MINES ParisTech | Cheng X.,Institute Des Science Et Industries Du Vivant Et Of Lenvironnement Agroparistech | And 5 more authors.
Neurophysiologie Clinique | Year: 2016

Objectives: Assessment of current practice and the need for tele-transmission and remote interpretation of EEG in France. Transmission of EEG to a distant center could be a promising solution to the problem of decreasing availability of neurophysiologists for EEG interpretation, in order to provide equity within health care services in France. This practice should logically follow the legal framework of telemedicine and the recommendations that were recently edited by the Société de neurophysiologie clinique de langue française (SNCLF) and the Ligue française contre l'épilepsie (LCFE). Methods: A national survey was designed and performed under the auspices of the SNCLF. Results: This survey reveals that there is an important gap between the official recommendations and the "reality on the ground". These local organizations were mainly established through the impulse of individual initiatives, rarely driven by health regulatory authorities and sometimes far from legal frameworks. For the majority, they result from a need to improve medical care, especially in pediatrics and neonatology, and to ensure continuity of care. When present, tele-transmission of EEG is often only partially satisfactory, since many technical procedures have to be improved. Conversely, the lack of tele-transmission of EEG would penalize medical care for some patients. Conclusions: The survey shows both the wealth of local initiatives and the fragility of most existing networks, emphasizing the need for better cooperation between regulatory authorities and health care professionals to establish or improve the transmission of EEG in France. © 2016 Elsevier Masson SAS.

Kleinschroth F.,CIRAD - Agricultural Research for Development | Kleinschroth F.,Bangor University | Kleinschroth F.,Institute Des Science Et Industries Du Vivant Et Of Lenvironnement Agroparistech | Gourlet-Fleury S.,CIRAD - Agricultural Research for Development | And 3 more authors.
Ecosphere | Year: 2015

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. © 2015 Kleinschroth et al.

Amichi H.,Institute Des Science Et Industries Du Vivant Et Of Lenvironnement Agroparistech | Bouarfa S.,IRSTEA | Kuper M.,CIRAD - Agricultural Research for Development | Ducourtieux O.,Institute Des Science Et Industries Du Vivant Et Of Lenvironnement Agroparistech | And 5 more authors.
Irrigation and Drainage | Year: 2012

The use of groundwater in irrigated agriculture is often regarded as an effective way of increasing farm productivity. However, the effects of differential access to groundwater by farmers have rarely been studied at the microeconomic scale, particularly the possibly negative effects of marginalization of small farmers. During the hydraulic crisis that has affected Algerian irrigation schemes since the 1980s, groundwater has become a major source of irrigation for farmers. A process of farm differentiation occurred linked to farmers' access to groundwater, causing social inequity. To understand the differentiation of farms in the Ouarizane irrigation scheme, we first undertook a historical inquiry. Second, we used a participatory prospective approach to analyse possible changes in farming systems after the adoption of a new land reform. Our results confirmed that access to groundwater has become a structural factor in the differentiation of farms and in land concentration in Algerian irrigation schemes. Land concentration and the marginalization of small farmers are likely to worsen when the new land law is applied. © 2012 John Wiley & Sons, Ltd.

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