Charly Favier

Charly Favier
French National Centre for Scientific Research | CNRS · Institut des Sciences de l'Evolution

PhD

About

107
Publications
27,118
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2,603
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Publications

Publications (107)
Article
Full-text available
Although it is well known that humans substantially altered the Malagasy ecosystems, the timing of the human arrival as well as the extension of their environmental impact is yet not well understood. This research aims to study the influence of early human impact and climate change on rainforests and wildlife in northern Madagascar during the past...
Article
The aim of this study is to provide the drivers of long-term fire dynamics in various regions of Sub-Saharan Africa using a synthesis of updated sedimentary charcoal records, from 25,000 years ago to the present. We used the charcoal data currently available in the Global Paleofire Database, updated with the most recent published charcoal data, to...
Article
This paleoecological study investigates vegetation variability and fire regimes in Northeastern Brazil (NEB)’s Cerrado. We present high-resolution pollen and charcoal records from a palm swamp located in a Cerrado in Chapada das Mesas National Park, in the southwest of Maranhão State. The Vereda do Dodó sedimentary core is 187 cm deep and covers th...
Preprint
Madagascar comprises one of the Earth's biologically richest, but also one of most endangered, terrestrial ecoregions. Although it is obvious that humans substantially altered its natural ecosystems during the past decades, the timing of arrival of humans on Madagascar as well as their environmental impact is not well resolved. In this context, thi...
Article
A core from a peat bog in the “Niayes” region, northwest of Senegal, provides a valuable insight into the evolution of the landscape and fire regime related to the West African Monsoon rainfall and to human impact over the Holocene. The high-resolution multiproxy approach based on stable carbon isotopic composition (δ¹³C), Rock-Eval® thermal analys...
Article
The early Pleistocene was driven by 41 kyr glacial cycles that have been rarely characterized in continental records, especially in South America. Most of long-term records derive from marine records (e.g.sea surface temperatures (SST)) and have been widely used to infer past climate dynamics but implications for the continent have rarely been eval...
Article
Full-text available
Madagascar houses one of the Earth’s biologically richest, but also one of most endangered, terrestrial ecoregions. Although it is obvious that humans substantially altered the natural ecosystems during the past decades, the timing of arrival of early inhabitants on Madagascar as well as their environmental impact is still intensively debated. This...
Article
Holocene paleoecological studies in tropical Africa are rare because most lakes either dried out at the termination of the African Humid Period or have since filled up. However, tropical sedge marshes can be an alternative to perform long-term ecological studies. The Lopé National Park (LNP) in Gabon is a mosaic of forest and savanna enclosed in th...
Article
Understanding processes that explain phytolith assemblages and their concentration in the soil and sediments is essential to interpret long-term ecological changes. The present study shows modern phytolith assemblages and their relationship with the vegetation cover in the Caatinga biome, state of Ceará, northeastern Brazil. We collected recent sam...
Article
The idea that tropical forest and savanna are alternative states is crucial to how we manage these biomes and predict their future under global change. Large-scale empirical evidence for alternative stable states is limited, however, and comes mostly from the multimodal distribution of structural aspects of vegetation. These approaches have been cr...
Article
Significance We develop a biogeographic approach to analyzing the presence of alternative stable states in tropical biomes. Whilst forest–savanna bistability has been widely hypothesized and modeled, empirical evidence has remained scarce and controversial, and here, applying our method to Africa, we provide large-scale evidence that there are alte...
Article
Full-text available
We present a new 52 m composite record (COL17c) composed of five sedimentary sequences retrieved from the Colônia basin (Southeastern Brazil). The COL17c record is composed of two main sub-units deposited under different regimes: a peatland above ∼14 m and lacustrine sediments below. Sedimentary description and core scanning (MSCL and XRF) are firs...
Article
The northeastern region of Brazil is the most densely populated and biodiverse semi-arid regions of the planet. Effects of the natural climate variability and colonization on the landscape have been described since the beginning of the 16th century but little is known about their effects on natural resources. Climate projections predict temperature...
Article
Until now, sedimentary DNA (sedDNA) studies have only focused on cold and temperate regions were DNA is relatively well preserved. Consequently, the tropics, where vegetation is hyperdiverse and natural archives are rare, have been neglected and deserve attention. In this study, we used next-generation sequencing to barcode sedDNA from Lake Sele, l...
Article
Full-text available
Tree cover is a key variable for ecosystem functioning, and is widely used to study tropical ecosystems. But its determinants and their relative importance are still a matter of debate, especially because most regional and global analyses have not considered the influence of agricultural practices. More information is urgently needed regarding how...
Data
Age estimations of the trees at the mode of the diameter distribution for the four genera that are monospecific in the SRI. The mode of the diameter distribution across the SRI, information on growth data, including number of trees (n), the diameter (dbh) range and the mean and standard error of the annual diameter increment (SE), and age estimatio...
Data
Age data for the four study species based on published tree-ring data. Mean ages and corresponding estimated dates are shown in Figure 2 (Main Text). C = Cameroon; RC = Republic of the Congo; CAR = Central African Republic; n = number of stem discs. DOI: http://dx.doi.org/10.7554/eLife.20343.010
Data
Relative performance of commonly used growth models for the four genera that are monospecific in the SRI. Growth model functions used to analyze the variation in tree growth (MAId, in cm.yr−1) with tree size (DBH, in cm) are detailed below. For the biological interpretation of parameters, Max is the maximum growth or growth optimum (in cm.yr−1), Do...
Data
Data documenting paleoenvironmental changes (Figures 1 and 3, Main Text) during the last 1000 years in the SRI. C = Cameroon; RC = Republic of the Congo; CAR = Central African Republic; W Africa = West Africa. Numbers refer to the map (Figure 1 Main Text). References are indicated. DOI: http://dx.doi.org/10.7554/eLife.20343.012
Data
Chronology of the historical events from the beginning of the 15th century to the present occurring or influencing human populations in the SRI. Precise dates or time spans are related to local or more general events. References are indicated. DOI: http://dx.doi.org/10.7554/eLife.20343.015
Data
Trait information and characteristics of the diameter distribution for the 176 study genera across the SRI. Botanical family was extracted from the African Plant Database of the Conservatoire et Jardin botaniques de la Ville de Genève and South African National Biodiversity Institute, Pretoria (http://www.ville-ge.ch/musinfo/bd/cjb/africa/recherche...
Data
Synthesis of the 63 AMS radiocarbon and the two OSL dates documenting human activities (Figure 3 Main Text) during the last 1000 years in the SRI. C = Cameroon; RC = Republic of the Congo; CAR = Central African Republic; AA = AMS Laboratory, University of Arizona (USA); Beta = Beta Analytic (USA); Erl = Erlangen AMS Facility (Germany); Gif = Gif-su...
Data
SQL codes for the Bayesian analysis of the radiocarbon dates. DOI: http://dx.doi.org/10.7554/eLife.20343.014
Article
Full-text available
The populations of light-demanding trees that dominate the canopy of central African forests are now aging. Here, we show that the lack of regeneration of these populations began ca. 165 ya (around 1850) after major anthropogenic disturbances ceased. Since 1885, less itinerancy and disturbance in the forest has occurred because the colonial adminis...
Article
Full-text available
The tropical moist forests (TMF) of the Congo Basin are extremely diverse in terms of structure and functional diversity. Previous paleoecological work suggests that these forests have experienced dramatic changes over the last millennia, related to climate or humans. These disturbances still influence today's repartition of forests and savannas as...
Article
Surface soil samples were collected in three mountainous massifs in north-eastern Brazil to characterize the different vegetation types according to their respective pollen assemblages. Complementary approach between pollen and vegetation data shows that the pollen rain accurately reflects the following three main forest types: i) a dense ombrophil...
Article
Full-text available
As tropical forests are complex systems, they tend to be modelled either roughly via scaling relationships or in a detailed manner as high-dimensional systems with many variables. We propose an approach which lies between the two whereby succession in a tropical forest is viewed as a trajectory in the configuration space of a dynamical system with...
Article
1. Understanding the environmental determinants of forests deciduousness i.e. proportion of deciduous trees in a forest stand, is of great importance when predicting the impact of ongoing global climate change on forests. In this study, we examine (i) how forest deciduousness varies in relation to rainfall and geology, and (ii) whether the influenc...
Article
Full-text available
The Colônia Deep Drilling Project held its first International Continental Scientific Drilling Program (ICDP) workshop in September 2014 at the University of São Paulo (Brazil). Twenty-seven experts from six countries discussed the feasibility and the expectations of a deep drilling in the structure of Colônia located at the southwestern margin of...
Presentation
Full-text available
Review of the events that happened in the northern Congo basin during the last 1,000 yr. Positive impact of human disturbances on the regeneration of light-demanding trees. Negative impact of the European colonization and following events on human populations and tree regeneration.
Poster
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We aim to improve our knowledge of the dynamic of the vegetation in Central Africa during the last 5 kyrs and to discuss the main hypothesis described in the literature - humans versus climatic impacts - both suggested as responsible of the Congo basin rainforest decline observed between 3 and 2.5 kyrs. We use the carbon isotopic composition of wel...
Poster
Full-text available
The canopy of central African moist forests is dominated by light-demanding trees. Most of these species show a distribution of diameters that indicates a regeneration shortage. Here we show through the combined analysis of botanical, palaeoecological, archaeological and historical data that most of these trees are not older than ca. 180 years. Thi...
Article
The recent paper in this journal by Thié blemont et al. (2013) (TH) discusses mainly about the coarse-grained stone lines (S L) in central Africa, particularly the most recent one, and also the fine-grained Cover Horizon (C H) above the S L. This study supplies various interesting precisions on the implementation of S L and C H. So ''geochronologic...
Book
Full-text available
http://www.cnrs.fr/fr/pdf/inee/prospective-eco-tropicale/#/1/
Conference Paper
Full-text available
Tropical forests are not believed as pristine anymore. Their structure and specific composition are induced by past climatic and human disturbances over years. In the African moist forests, the emergent trees are mainly light-demanding. These trees are considered to derive from the recent disturbances of the last centuries. Most of them are exploit...
Data
Our research shows that tropical forests of Central Africa are highly diverse: some are very dynamic and more or less disturbed, others are less so; some have a great diversity of trees, others very little. This variety is the wealth of the second largest rainforest in the world and explains its potential to react differently to different anthropog...
Article
Full-text available
Fires have played an important role in creating and maintaining savannas over the centuries and are also one of the main natural disturbances in forests. The functional role of fires in savannas and forests can be investigated through examining sedimentary charcoal in order to reconstruct long-term fire history. However, the relationship between ch...
Poster
Full-text available
La forêt tropicale africaine a longtemps été considérée comme vierge du passage de l’homme. Cependant, plusieurs études récentes en paléoécologie et archéologie ont démontré la présence d’activités humaines anciennes à partir d’indices paléoenvironnementaux (i.e. pollens de plantes anthropophiles) et d’artefacts (i.e. tessons de céramique). Ces étu...
Article
Full-text available
Central Africa includes the world's second largest rainforest block. The ecology of the region remains poorly understood, as does its vegetation and archaeological history. However, over the past 20 years, multidisciplinary scientific programmes have enhanced knowledge of old human presence and palaeoenvironments in the forestry block of Central Af...
Article
So far, no phytolith extraction protocols have been tested for accuracy and repeatability. Here we aim to display a phytolith extraction method combining the strengths of two widely used protocols, supplemented with silica microspheres as exogenous markers for quantifying phytolith concentrations. Phytolith concentrations were estimated for samples...
Article
Full-text available
Tracing human history in west central Africa suffers from a scarcity of historical data and archaeological remains. In order to provide new insight into this problem, we reviewed 733 radiocarbon dates of archaeological sites from the end of the Late Stone Age, Neolithic Stage, and Early and Late Iron Age in Cameroon, Gabon, Central African Republic...
Article
Full-text available
Paleo-data suggest that East African mountain treelines underwent an altitudinal shift during the Last Glacial Maximum (LGM). Understanding the ecological and physiological processes underlying treeline response to such past climate change will help to improve forecasts of treeline change under future global warming. In spite of significant improve...
Article
Full-text available
Tracing human history in west central Africa suffers from a scarcity of historical data and archaeological remains. In order to provide new insight into this problem, we reviewed 733 radiocarbon dates of archaeological sites from the end of the Late Stone Age, Neolithic Stage, and Early and Late Iron Age in Cameroon, Gabon, Central African Republic...
Article
Full-text available
Bayon et al. (Reports, 9 March 2012, p. 1219) claim that the “rainforest crisis” in Central Africa centered around 2500 years before the present “was not triggered by natural climatic factors” and that it was caused by widespread deforestation resulting from the arrival of the Bantu colonists. However, there is a consensus among palaeoecologists th...
Article
Aim To describe patterns of tree cover in savannas over a climatic gradient and a range of spatial scales and test if there are identifiable climate-related mean structures, if tree cover always increases with water availability and if there is a continuous trend or a stepwise trend in tree cover. Location Central Tropical Africa. Methods We compar...
Article
Changes in C4 grass distribution and abundance are frequently observed in Quaternary, Holocene and future environmental-change scenarios. However, the factors driving these dynamics are not fully understood, and conflicting theories have been reported. In this paper, we present a very large dataset of modern altitudinal distribution profiles of C3...
Conference Paper
Long-term ecological records are essential to understanding past responses of vegetation to climate change and human activity. As part of a multi-disciplinary project (Coforchange), we undertook research into the past conditions that prevailed during the Holocene in a region that currently holds the world's second largest rainforest. Tropical Moist...
Article
Full-text available
Quantitative reconstructions of the past climate statistics from geochemical coral or mollusk records require quantified error bars in order to properly interpret the amplitude of the climate change and to perform meaningful comparisons with climate model outputs. We introduce here a more precise categorization of reconstruction errors, differentia...
Article
Full-text available
Past limnological conditions of Lake Mbalang (7°19´ N, 13°44´ E, alt: 1130 m) and vegetation type were reconstructed from diatoms and sedimentary stable carbon isotope records (δ13C) since 7200 cal yrs BP. The data showed that before 3600 yrs cal BP the water column was preferentially cold and stable except around 5000–5300 cal yrs BP where diatom...
Article
Full-text available
Past limnological conditions of Lake Mbalang (7°19′ N, 13°44′ E, altitude: 1130 m) and vegetation type were reconstructed from diatoms and sedimentary stable carbon isotope records (δ<sup>13</sup>C) since 7200 cal yr BP. The data showed that before 3600 cal yr BP, the water column was dominantly stable except around 5000–5300 cal yr BP where diatom...
Article
The relationship between species abundance, the variance of the number of individuals, and species occupancy is a fundamental ecological characteristic of a community. Moreover, this relationship varies across scales, and any model for the variance-occupancy-abundance (VOA) relationship has to address its scale dependency in a consistent way. In th...
Article
Full-text available
To calibrate a model of the relationship between bio-proxies (pollen, phytoliths and δ13C of soil organic matter) and woody cover, measured as the leaf area index (LAI). This relationship, applied in palaeosequences, enables reconstruction of past savanna tree cover. The samples are from tropical Africa. Modern soil samples are from the Central Afr...
Article
Full-text available
Reconstructions of the past climate from proxy records involve a wide range of uncertainties at every step of the process. These uncertainties and the subsequent error bar in the reconstruction of a paleoclimatic variable need to be understood and quantified in order to properly interpret the reconstructed variability and to perform meaningful comp...
Article
The goal of this study is to propose a new classification of African ecosystems based on an 8-year analysis of Normalized Difference Vegetation Index (NDVI) data sets from SPOT/VEGETATION. We develop two methods of classification. The first method is obtained from a k-nearest neighbour (k-NN) classifier, which represents a simple machine learning a...
Article
Full-text available
An original method is proposed for estimating past carbon emissions from fires in order to understand long-term changes in the biomass burning that, together with vegetation cover, act on the global carbon cycle and climate. The past carbon release resulting from paleo-fires during the Holocene is examined using a simple linear model between measur...
Article
Upscaling population models from fine to coarse resolutions, in space, time and/or level of description, allows the derivation of fast and tractable models based on a thorough knowledge of individual processes. The validity of such approximations is generally tested only on a limited range of parameter sets. A more general validation test, over a r...
Article
Full-text available
We present geochemical studies have been conducted on two lake sediment cores collected in 2007 in Lake Ossa in the Sanaga Basin in south-western Cameroon. We show a significant fragmentation of the forest between 2500 and 2300 BP corroborating results of Ngomanda et al., (2009). These authors suggest an important aridification marked by a long dry...