Stéphane Guitet

Office National des Forêts · DT Guyane

Tropical rainforests host exceptional biodiversity and provide important ecosystem services, but they are facing anthropogenic and climatic threats. Preserving the genetic diversity of forest tree populations is essential for their capacity to adapt and exhibit resilience to environmental changes and anthropogenic pressures. Here, we collected cons...

La carte des habitats forestiers présentée précédemment a été élaborée en s'appuyant à la fois sur des campagnes d'inventaires de terrain couvrant plus de 650 ha sur une trentaine de sites répartis sur toute la Guyane, mais aussi sur l'exploitation de données de télédétection : images satellites multi-spectrales SPOT du couvert forestier et modèle...

Derrière ce décor de forêt monumentale se cache en réalité toute une diversité de paysages d'habitats et de faciès forestiers invisibles aux automobilistes et habitants du littoral cantonnés sur une petite frange du territoire, mais qui se révèle aux yeux des travailleurs des bois, villageois et marcheurs au long cours franchissant la lisière ou à...

Cette étude offre un aperçu et une analyse synthétique des outils de connaissance disponibles dans les Régions Ultra-Périphériques (RUP) françaises (La Réunion, Mayotte, Saint-Martin, Guadeloupe, Martinique et Guyane) pour la priorisation de la conservation des écosystèmes et des espèces, dans une perspective de planification spatiale de la conserv...

Medium-and large-sized vertebrates play a key role in shaping overall forest functioning. Despite this, vertebrate interactions, from competition to mutualism, remain poorly studied, even though these interactions should be taken into account in our conservation and management strategies. Thus, we tackled the question of vertebrate co-occurrence in...

Aim :Despite their often high‐trophic position and their contribution to many ecosystem functions, little is known about the factors affecting assemblage structure of medium‐ and large‐sized neotropical vertebrates. We examined the relative roles played by the physical and biological environment, and by purely spatial processes, in shaping the comp...

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Disturbance controls rainforest dynamics and, according to the Intermediate Disturbance Hypothesis (IDH), is a key driver of local diversity. Variations in disturbance regimes and their consequences for regional diversity at broad spatiotemporal scales are still poorly understood. Using multi-disciplinary large-scale inventories and LiDAR acquisiti...

Availability of digital elevation models (DEM) of increased spatial resolution has triggered interest in texture-based methods for automated geomorphometry. This prospect is all the more appealing concerning tropical countries for which mapping of geomorphic entities has remained limited despite its relevance for natural resource assessment and lan...

modélisation spatiale des zones humides en Guyane française

Tables rondes biodiversité ultramarine du Sénat

L’étude vise à évaluer la faisabilité d’une cartographie régulière des habitats forestiers dans les outre-mer permettant : (1) de répondre aux besoins de rapportages internationaux, concernant les thèmes biodiversité et carbone ; (2) de produire des indicateurs pour le pilotage des politiques nationales relatives à ces thèmes ; (3) de faciliter la...

Revegetation of abandoned aquaculture regions should be a priority for any integrated coastal zone management (ICZM). This paper examines the potential of a matchless time series of 20 very high spatial resolution (VHSR) optical satellite images acquired for mapping trends in the evolution of mangrove forests from 2001 to 2015 in an estuary fragmen...

Tropical forests store large amounts of biomass despite they generally grow in nutrient-poor soils, suggesting that the role of soil characteristics in the structure and dynamics of tropical forests is complex. We used data for >34 000 trees from several permanent plots in French Guiana to investigate if soil characteristics could predict the struc...

Line transect surveys are widely used in neotropical rainforests to estimate the population abundance of medium- and large-sized vertebrates. The use of indices such as Encounter Rate has been criticized because the probability of animal detection may fluctuate due to the heterogeneity of environmental conditions among sites. In addition, the morph...

Modélisation de la répartition spatiale du hocco alector en Guyane française : un appui pour la gestion cynégétique de l'espèce Avec la forte augmentation de la population guyanaise, les pressions anthropiques vont s'intensifier sur la frange littorale et risquent d'impacter les habitats de la faune sauvage ainsi que les populations animales qui le...

Mapping forest aboveground biomass (AGB) has become an important task, particularly for the reporting of carbon stocks and changes. AGB can be mapped using synthetic aperture radar data (SAR) or passive optical data. However, these data are insensitive to high AGB levels (>150 Mg/ha, and >300 Mg/ha for P-band), which are commonly found in tropical...

The future of tropical managed forests is threatened by climate change. In anticipation of the increase in the frequency of drought episodes predicted by climatic models for intertropical regions, it is essential to study commercial trees’ resilience and vulnerability to water stress by identifying potential interaction effects between selective lo...

Technical recommendations for forest managers and foresters in French Guiana

The Black Curassow (Crax alector) is a large game bird with Vulnerable conservation status found in north-central South America. We examined its distributional pattern across French Guiana using a large number of environmental descriptors at 3 scales of analysis: landscape, forest type, and microhabitat. We used a hierarchical model with temporary...

The influence of geomorphological features on rain-forest diversity has been reported in different Amazonian regions. Soil filtering is often assumed to underlie the observed geomorphic control on the floristic composition but other hypotheses related to biogeography or long-term forest dynamics are also possible. We tested relationships between ge...

Planning policies for rapid development in French Guiana will require the conversion of forested areas, thus contributing to global warming. Guiana’s policy-makers will need to integrate the preservation of eco-system services into their planning decisions. The GuyaSim project was conduc- ted to produce more in-depth knowledge on these services (ca...

Precise mapping of above-ground biomass (AGB) is a major challenge for the success of REDD+ processes in tropical rainforest. The usual mapping methods are based on two hypotheses: a large and long-ranged spatial autocorrelation and a strong environment influence at the regional scale. However, there are no studies of the spatial structure of AGB a...

Le massif forestier guyanais présente à la fois une grande originalité en termes de biodiversité, un bon état de conservation, une forte contribution au stock de carbone amazonien et une dynamique socio-économique très rapide. Les connaissances sur la diversité des écosystèmes forestiers de Guyane française restent cependant insuffisantes pour asse...

Le massif forestier guyanais présente à la fois une grande originalité en termes de biodiversité, un bon état de conservation, une forte contribution au stock de carbone amazonien et une dynamique socio-économique très rapide. Les connaissances sur la diversité des écosystèmes forestiers de Guyane française restent cependant insuffisantes pour asse...

This xls file provides the dataset used to develop the spatial distribution model of Above-Ground Biomass for French Guiana (see Guitet et al. 2015 - PlosONE). It gives the number of trees per DBH class and 1000 simulations of the mean values of Wood Specific Gravity for each 2507 plots (0.4-0.5 ha in size). The plots are located using projected co...

Tropical rainforests exhibit a high alpha-diversity and a complex local structure that hides patterns at regional scale. Thus little is known about spatial distribution of tree species and variation of communities’ composition at operational scales. Nevertheless this information is essential to assure the sustainability of forest management in the...

Whereas broad-scale Amazonian forest types have been shown to influence the structure of the communities of medium-to large-bodied vertebrates, their natural heterogeneity at smaller scale or within the terra firme forests remains poorly described and understood. Diversity indices of such communities and the relative abundance of the 21 most common...

Geomorphic landscape features have been suggested as indicators of forest diversity. However, their explanatory power has not yet been explicitly tested at a regional scale in tropical rainforest. We used forest inventories conducted according to a stratified sampling design (3,132 plots in 111 transects at 33 sites) and holistic multi-scale geomor...

Planning policies for rapid development in French Guiana will require the conversion of forested areas, thus contributing to global warming. Guiana's policy-makers will need to integrate the preservation of ecosystem services into their planning decisions. The GuyaSim project was conducted to produce more in-depth knowledge on these services (carbo...

Le catalogue des habitats forestiers de Guyane, premier dans son genre, permet aujourd’hui d’identifier les différents types d’habitats, de les caractériser et de les cartographier, grâce à l’utilisation de technologies pointues. Ce catalogue, réalisé par le pôle recherche et développement de l’ONF Guyane est l’aboutissement d’un long travail pluri...

A molecular screening of wild-caught rodents was conducted in French Guiana, South America to identify hosts of the hantavirus Maripa described in 2008 in a hantavirus pulmonary syndrome (HPS) case. Over a 9-year period, 418 echimyids and murids were captured. Viral RNA was detected in two sigmodontine rodents, Oligoryzomys fulvescens and Zygodonto...

En 2009, l’ONF s’associait à l’ONCFS, au Parc Amazonien de Guyane, à l’UMR EcoFoG et à l’Herbier de Cayenne, dans un vaste programme de recherche, intitulé HABITATS. Son objectif : étudier les relations entre sol, végétation et grande faune pour définir une typologie des habitats forestiers de terre ferme, qui couvrent plus de 80 % du territoire. R...

In tropical rainforests, the sustainability of selective logging is closely linked to the extent of collateral stand damage. The capacity to measure the extent of such damage is essential for calculating carbon emissions due to forest degradation under the Reducing Emissions from Deforestation and Forest Degradation (REDD+) process. The use of remo...

a b s t r a c t This study aimed to correlate logging intensity with canopy opening using medium-resolution satellite images (SPOT-type) on a sample of 15 blocks totaling more than 3300 ha in two French Guianan forests with different reliefs. The maps obtained show the cumulative impacts on the canopy over the entire log-ging period (2008–2010). Th...

In this paper two geomorphologic maps (landform level and landscape level) are presented covering the French Guianan rainforest (84,000 km2) using full-resolution Shuttle Radar Topography Mission (SRTM) data. The entire country was segmented into 224,000 landform units on the basis of an original object-oriented approach using a modified counting b...

Despite the widely accepted idea of an area covered with a homogeneous forest, french Guiana is actually very heterogeneous in both distribution of species and forest landscapes. We will discuss the various usual ways for exploration of plant biodiversity and their development through the introduction of a botanical conservatory in french Guiana. T...

Forest successional processes following disturbance take decades to play out, even in tropical forests. Nonetheless, records of vegetation change in this ecosystem are scarce, increasing the importance of the chronosequence approach to study forest recovery. However, this approach requires accurate dating of secondary forests, which until now was a...

This article reviews an experimental system set up in French Guiana to test different selective thinning methods that started ten to fifteen years after logging in order to reconstitute commercially viable stands within the shortest time. The thinning methods tested involve a combination of selective intervention within a radius of 10 metres around...

Habitats naturels, géomorphologie, biodiversité, forêt tropicale humide, Guyane française, biogéographie, typologie forestière, gestion de la biodiversité, cortèges faunistiques, relations faune-habitats, relations sol-végétation. Objectifs des recherches Les habitats naturels correspondent au niveau d'expression de la biodiversité le plus opératio...

This article reviews an experimental system set up in French Guiana to test different selective thinning methods that started ten to fifteen years after logging in order to reconstitute commercially viable stands within the shortest time. The thinning methods tested involve a combination of selective intervention within a radius of 10 metres around...

Cet article fait le bilan d'un dispositif expérimental installé en Guyane française pour tester différentes modalités d'éclaircie sélective, mises en oeuvre dix à quinze ans après exploitation, en vue d'obtenir une reconstitution rapide du peuplement commercial. Les modalités d'éclaircie testées sont de type mixte. Elles combinent une intervention...

Cette étude s'inscrit dans le cadre du suivi de l'exploitation forestière à faible impact en forêt tropicale humide. L'importance des dégâts liés à l'exploitation forestière conditionne fortement la durabilité de cette activité et un contrôle efficace de la qualité des travaux forestiers s'impose donc au gestionnaire. Dans cette étude, l'imagerie s...

Caractériser la surface terrestre est important pour analyser la diversité des paysages et pour appréhender les changements d'utilisation du sol. En général, dans les cartographies de végétation de l'Amazonie et du plateau des Guyanes, la forêt est représentée sous la forme d'une grande couche verte homogène (TREES web page; Eva et al., 2004). Les...

This study is part of the activities carried out to monitor low-impact logging operations in humid tropical forests. The sustainability of these activities is highly dependent on the scale of logging damage, and managers therefore need to carry out effective checks on the quality of forestry work. In this study, remote sensing was used to track the...

L'exploitation à faible impact (EFI), plus connue sous son appellation anglophone de RIL (reduced impact logging) est un ensemble de techniques sylvicoles développées depuis près de 15 ans afin de limiter les impacts de l'exploitation forestière en milieu tropical humide et de garantir la durabilité des prélèvements de bois dans cet environnement e...

Afin d’améliorer l’efficacité économique et de mieux maîtriser les impacts environnementaux, la réalisation des travaux d’exploitation en Guyane a justifié une étude de diagnostic post-exploitation dont les principaux enseignements sont présentés. La nécessaire évolution des pratiques d’exploitation habituelles doit impérativement s’inscrire dans u...