The climatic debt explained

I guess some of you may wonder: what the hell is the climatic debt? Well, in ecology, this term is used to refer to communities of living organisms being in a state of disequilibrium with climate (cf. the equilibrium between community composition and climatic conditions has been disrupted). This is best illustrated by time-lagged response of living organisms to climate change. The inertia of long-lived organisms such as trees or perennial plants after a climate-forcing event makes forest ecosystems particularly prone to the climatic debt.

In a recent paper led by Romain Bertrand, we found that the magnitude of the disequilibrium with climate, aka climatic debt, in understory plant communities across the French forests (see map) increases with the severity of baseline temperature conditions, the exposure to climate warming and species thermal tolerance.


Map displaying the spatial distribution of the climatic debt in understory plant communities across French forests. Darker red colors indicate a higher climatic debt (cf. a greater disequilibrium between current plant community composition and current climatic conditions) while blue colors indicate no climatic debt (vegetation is in equilibrium with current climatic conditions). Note that mountainous forests in the Alps, the Massif Central, the Pyrenees and part of the Vosges have paid off their climatic debt (Map: R. Bertrand).

I’m really proud to write these few lines, not only because this is an important result (sorry I might be biased here) but mostly because it is always inspiring, rewarding and cool to work with a good buddy on a fun topic. Romain and I discussed this idea of “explaining the climatic debt” a very long time ago. It all started in 2011, few days after Romain’s original work on the assessment of the climatic debt in french forests’ understory plant communities was published. Well, we were not smart enough to use the fancy “climatic debt” at that time but reported it as “biotic responses lagging behind climate change” instead. Anyway, the thing is that we received a thorough (and inspiring) commentary from Pieter De Frenne and his colleagues arguing that the climatic debt we found in understory plant communities of temperate deciduous forests could be the result of changes in forest management practices. The reasoning behind this argument being that the abandonment of coppicing (a traditional sylvicultural practice in Europe: see picture below) and the subsequent natural succession towards mature close forests may provide microclimatic conditions that buffer understory plant communities against macroclimate warming. This is indeed a very important hypothesis and you can learn more on the potential importance of microclimate as a moderator of plant responses to macroclimate warming by reading the excellent paper written by Pieter De Frenne and his team. Although neither their commentary nor our reply was published, this was a fruitful discussion that has generated new and exiting findings.

The seminal analyses that we provided five years ago in our reply to the commentary just involved the respective impacts of macroclimate warming and changes in understory light conditions on the magnitude of the climatic debt and demonstrated that changes in understory light conditions had a minor impact on the climatic debt, as it is also the case in the now published paper. It would have been a shame to stop there given the efforts made to provide a convincing reply (we might have been too much convincing on this). So, we elaborated a list of the potential drivers involved in the climatic debt that we observed in understory forest plant communities. In that respect, Romain went far beyond our initial list and provided a very comprehensive (23 explanatory variables) analysis of the potential determinants of the climatic debt not only involving environmental (i.e. baseline conditions and exposure to environmental changes) and anthropogenic (e.g. sylvicultural practices, land-use changes, habitat fragmentation) constraints but also plant traits and characteristics involved in persistence (e.g. species’ life span and thermal tolerance) and migration (e.g. species’ dispersal limitation) mechanisms.

Although we expected climate-change exposure to be an important determinant (plants are more likely to lag behind climate change in locations where the magnitude of the change is the highest), we were very surprised to find that both baseline temperature conditions and species’ intrinsic ability to tolerate water and thermal stresses outweigh the impact of climate-change exposure. Warmer baseline conditions (cf. lowland forests at low latitudes) contribute to a high climatic debt and yet these ecosystems are usually given less priority than cold ecosystems (e.g. mountains) in conservation biology. Similarly, species’ persistence mechanisms as a response to climate change have been neglected so far due to the strong emphasis on migration mechanisms involved in climate-driven range shifts that are particularly pronounced along the elevation gradient where short distances between isotherms allow plants to move upslope. And yet, both lowland ecosystems and persistence mechanisms are very important to consider, especially so for forest plant which dispersal abilities are very limited. Consequently and importantly, persistence mechanisms outweigh migration mechanisms in explaining the climatic debt in forest ecosystems. We also note that lowland ecosystems and warm climates in general are richer in stress-tolerant plants, which could be a reason why warmer climates are more likely to harbour plant communities lagging behind climate change.


Carpet of flowering bluebells (Hyacinthoides non-scripts) in a coppice dominated by beech (Fagus slvatica) and hornbeam (Carpinus betulus) (Vadencourt Wood, 80560 Contay, France). Due to its wide climatic-niche breadth and its affinity for moist and buffered microhabitats, bluebells likely contribute to increase the climatic debt in the understory (Photo: J. Lenoir).

Unfortunately, plants can only tolerate a limited amount of change in temperature conditions and future climate change projections suggest temperature increases that may go far beyond the thermal tolerance of plants, thus initiating local extirpation events with potential cascading effects for living organisms relying on these habitat-forming species.

PhD opportunity on biodiversity in heterogeneous environments under contemporary climate change

WANTED: excellent candidates for a PhD position on “Biodiversity in heterogeneous environments“. Department of Biology at NTNU in Trondheim (Norway) can fund two PhD positions among 14 different topics. Together with Irja Ida Ratikainen (Behaviour and Evolution) and Bente Jessen Graae (Ecology), we would like to find an excellent and highly motivated candidate for going into the competition of the projects funded by the Department of Biology. Our project aims to test theories on how landscape topography with all its microclimatic variation affects species capacity to adapt or disperse in response to climate change. The approaches to study this topic will involve fieldwork, theoretical and/or macroecological methods. If this sounds interesting to you, please read more about the project here and here and then take contact with one of us before 22nd of January using the below email adresses:

Irja Ida Ratikainen:
Jonathan Lenoir:
Bente Jessen Graae:


Dédèle ?

C’est qui Dédèle (comprendre ddl pour degré de liberté) ? Mr, c’est quoi un ddl ? Un Dédé quoi ? Comme ce genre de questions revient assez fréquemment en cours ou TD de statistiques, je me suis dit qu’il était peut-être temps d’écrire un petit post dédié à mon amie Dédèle. De toute manière, lorsque cette question ne m’est pas posée directement, je peux lire la détresse (voir la peur) dans les yeux de l’assistance quand j’invoque Dédèle (rassurez vous, il ne s’agit pas là d’une messe noire à l’attention de Dédèle la déesse de Terra Statistica ! Quoique…). Bon ok, je dramatise un chouïa, une grande partie de l’auditoire en question y est complètement insensible, à tort ou à raison. Pauvre Dédèle, tellement impopulaire… Moi même, jusque très tard, j’ai navigué à vue dans les dédales (ou les dédèles devrais-je dire) de Terra Statistica sans vraiment connaître ni chercher à connaître cette bonne vieille Dédèle, pourtant un phare dans la nuit. Damned, j’avais tord… J’avais bien une vague idée de ce qu’elle pouvait bien représenter mais clairement, je m’en souciais guère. Et pourtant, on gagne à la connaître. Qui ça ? Ben Dédèle bien sure.

Dédèle, c’est en fait une variable à surveiller très régulièrement, tout comme on surveille la jauge du niveau de carburant pour éviter de tomber en rade, à moins que la panne sèche soit un objectif en soi… Bref, tu l’auras compris chèr(e) lecteur/lectrice, il faut voir Dédèle comme une réserve et éviter de la faire tomber à zéro. Je te vois venir… Oui, mais à quoi elle sert cette réserve ? Bonne question Jean-Noël (oui, c’est la fin d’année et les fêtes approchent). C’est vrai ça à quoi Dédèle peut bien servir ? Et bien à faire avancer ton modèle statistique tout simplement, que ce soit une Lada première génération (petit réservoir ou petit échantillon) ou bien une Maserati  dernier cri (gros reservoir ou gros échantillon). C’est là que la notion de degrés de liberté prend tout son sens. Ben ouais, tu auras la possibilité d’aller plus loin (cf. plus de liberté) avec un gros réservoir bien plein plutôt qu’avec un petit réservoir même plein. Si comme moi tu es fan de Magic The Gathering (oups je sens que je vais perdre le peu de lecteurs/lectrices qui ont eu le courage de commencer à lire ce post) tu peux aussi voir Dédèle (oui j’ai décidé que Dédèle a plusieurs visages) comme ta réserve de mana. Plus celle-ci est grande et plus tu as de liberté pour lancer tes sorts les plus puissants (bam le Jökulhlaups) ou tes grosses bébêtes préférées (et bim Emrakul). Bon, avec ta réserve de Dédèle tu ne lanceras pas de sort (gosh, je peux lire la deception dans ton regard) mais tu pourras invoquer des variables plus ou moins puissantes pour faire avancer ton modèle statistique (c’est vrai, c’est moins classe qu’une Maserati dernier cri, mais utile, parfois) et avaler toujours un peu plus de variance.

Mouais mais Mr, comment dépenser le contenu de la reserve de Dédèle ? Tu es encore là Jean-Noël ? Hummm, serais-tu toi aussi tombé sous le charme de Dédèle la sirène (je t’avais prévenu, Dédèle a plusieurs visages). Prends garde, elle pourait bien t’entraîner dans les abysses de Terra Statistica. Et bien, tout d’abord, il faut savoir que l’invocation d’une variable quelque soit sa nature (quantitative, ordinale, binaire, qualitative) a un coût. Par exemple une variable quantitative (cf. valeurs numériques continues) te coûtera 1 point de Dédèle. Pour une variable qualitative (cf. catégories ou groupes), il t’en coûtera autant que tu as de groupes ou de catégories moins un : le sacro-saint n-1 (Kali Ma Shakti de…). Accroche-toi Jean-Noël, Dédèle nous tire plus profondément dans les limbes de Terra Statistica. Pour une variable quantitative il t’en coûtera aussi n-1, en fait, mais dans ce cas n vaut 2. Mais pourquoi n-1 me diras-tu Jean-Noël. Et bien parce que chaque estimation de paramètre te fait perdre 1 point de Dédèle et que chaque modèle se construit en estimant un premier paramètre qui sert de point de référence (cf. intercept) pour toute tes variables explicatives qu’elles soient quantitatives ou qualitatives. Dans le cas de variables quantitatives, ce paramètre n’est autre que l’ordonnée à l’origine et pour les varibles qualitatives, il s’agit simplement de la moyenne de la varible à expliquer pour une des modalités qui jouera le rôle de point de référence (généralement la première modalité qui vient par ordre alphabétique ou croissant). Note que ce point de référence sera commun à toutes les variables explicatives de ton modèle. Ceci a pour avantage de faire de grosses economies dans ta dépense de points de Dédèle. Quand ta réserve de Dédèle tombe à zéro, ta Maserati ou ta Lada cale et aucune statistique ne peut être calculée pour les différents paramètres de ton modèle statistique, faute de degrés de liberté. Bref, plus il te reste de points dans ta réserve à Dédèle et plus les tests statistiques qui moulinent en arrière-plan seront puissants (cf. risque de deuxième type faible) pour détecter des effets, même petits, des variables explicatives sur ta variale à expliquer.

Voilà courageux/courageuse lecteur/lectrice, tu es arrivé(e) au bout de ce post interminable sur Dédèle, the goddess, et tu en sais un peu plus sur elle et son univers impitoyable. Si tu veux en savoir un peu plus, le mieux reste encore de la travailler au corps…

Bonne navigation en Terra Statistica.

Evidence Against MacArthur’s Latitude–Niche Breadth Hypothesis

According to Robert MacArthur, the realized niche breadth of species is positively associated with latitude (cf. MacArthur’s latitude-niche breadth hypothesis), namely niches in highly diverse tropical regions near the equator are narrower than in less diverse boreal and polar regions (MacArthur, 1972). If you want to know more on this hypothesis, I highly recommend to read the paper from Vázquez & Stevens (2004) who deeply discuss the concept behind this hypothesis and made a thorough meta-analysis of the evidence for or against the latitude-niche breadth hypothesis, concluding that the null hypothesis (i.e, that there is no correlation between latitude and niche width) cannot be rejected. According to Klaus Rohde (see his post on MacArthur’s latitude-niche breadth hypothesis), a priori assumptions of this hypothesis are flawed: “The latitude-niche breadth hypothesis makes equilibrium assumptions, implicitly and explicitly assuming that niche space is more or less saturated with species. However, there is much evidence for an overabundance of vacant niches and that most ecological including tropical systems are far from saturation” (for a discussion and examples see Rohde 2005).

In a recent paper published by Safaa Wasof who will soon defend her PhD, we tested the niche conservatism hypothesis among distant populations of the same species and for a fairly large number (n = 888) of native European vascular plant species occurring in both the Alps (central Europe) and Fennoscandia (northern Europe). In addition to that, we also compared the realized niche breadth between populations from the Alps and populations from Fennoscandia, assuming that niche breadth would be wider for populations thriving in Fennoscandia than for those thriving in the Alps according to MacArthur’s latitude-niche breadth hypothesis. Well, we found the opposite pattern: populations from central Europe in the Alps have, on average, a wider climatic niche breadth than populations from northern Europe in Fennoscandia, thus contradicting MacArthur’s latitude-niche breadth hypothesis. Although we compared only two regions and did not cover the entire latitudinal gradient from the Tropics to the North Pole, our result is cristal clear.

If you want to know more about this result, you are very welcome to read Safaa’s paper (Wasof et al., 2015). However, this result was not the central message of Safaa’s paper which we twisted on the niche conservatism hypothesis and its relevance for species distribution models. Here I would like to focus more specifically on MacArthur’s latitude-niche breadth hypothesis and the result we found. This is also a nice opportunity for me to present a slightly different set of analyses that we ran together with Safaa but which did not get into the manuscript or the appendices (Safaa’s paper is just the tip of the iceberg).

So, instead of using growing degree days (GDD) and the aridity index (AI) solely to capture species realized climatic niche, like we did in Safaa’s paper, we here used a larger set of bioclimatic variables (8 out of the 19 bioclimatic variables from WorldClim: BIO2, BIO5, BIO6, BIO7, BIO8, BIO15, BIO18, BIO19) that we subsequently reduced to a bi-dimensionnal climatic space by using a Principal Component Analysis (PCA). We used the 1-km resolution bioclimatic grids that we each clipped to the two study regions (see Figure 1A for an example based on BIO5) before running the PCA (Figure 1B). The resulting first (PC1: Figures 1C and 1D) and second (PC2: Figures 1E and 1F) PCA axes captured 49% and 24%, respectively, of the total inertia. Note that Figures 1C, 1D, 1E and 1F are showing the spatial distribution of the PC1 and PC2 variables of the analog climatic space solely (cf. purple point cloud in Figure 1B).

Study region and climatic space

Figure 1: Study area and climatic space

Focusing on the analog climatic space solely to make climatic niches comparable between the two regions (cf. same reference), we used a set of 440 species, out of the 888 species belonging to the common species pool, for which we had enough data to compute the climatic niche breadth across both regions and along both PC1 and PC2 axes. Figure 2 shows an example of the realized climatic niche of Corydalis cava across the PC1-PC2 bi-dimensionnal climatic space for both the Alps (on the right) and Fennoscandia (on the left).

Corydalis cava

Figure 2: Realized climatic niche of Corydalis cava across the PC1-PC2 bi-dimensionnal climatic space for both the Alps (in red) and Fennoscandia (in blue).

Corydalis cava

Corydalis cava (Source: Wikimedia Commons).

Niche breadth along both PC1 and PC2 was computed as the 95% confidence interval around the optimum value (cf. maximum density position). Figure 3 shows the result for all 440 studied species along PC1 (Figure 3A) and PC2 (Figure 3B). I guess statistical tests are useless here given the strength of the signal. For most European vascular plant species, populations from the Alps have wider realized climatic niche along both PC1 and PC2 than populations from Fennoscandia.

Niche breadth Alps vs Scandinavia

Figure 3: Realized climatic niche breadth for 440 vascular plant species occurring in both the Alps and Fennoscandia

This trend towards wider niches in the Alps than in Fennoscandia (Figure 3) invalidates MacArthur’s latitude–niche breadth hypothesis. In Safaa’s paper we discuss several potential drivers behind this result. My favorite one implies greater genetic diversity due to a diversity of refugia close to the Alps (Schönswetter et al., 2005), corresponding to greater habitat heterogeneity, thus increasing the likelihood for a species to widen its fundamental climatic niche in the Alps.


MacArthur (1972) Geographical ecology. Princeton University Press, Princeton

Rohde (2005) Nonequilibrium ecology. Cambridge University Press, Cambridge

Schönswetter et al. (2005) Molecular evidence for glacial refugia of mountain plants in the European Alps. Molecular Ecology, 14: 3547–3555.

Vázquez & Stevens (2004) The Latitudinal Gradient in Niche Breadth: Concepts and Evidence. The American naturalist, 164: E1–E19

Wasof et al. (2015) Disjunct populations of European vascular plant species keep the same climatic niches, Global Ecology and Biogeography, 24: 1401-1412

The Niche Concept under Contemporary Climate Change

I’m proud to announce the forthcoming PhD defense of Safaa Wasof who did her PhD under my supervision at Jules Verne University of Picardie (UPJV) within the research unit “Ecologie et dynamique des systèmes anthropisés” (Edysan, FRE3498 CNRS-UPJV). Safaa’s PhD defense is scheduled on Friday 27 November at 9H00 am at the Faculty of Pharmacy (Pôle Santé Saint Charles, 1 Rue des Louvels, 80037 Amiens Cedex, France). If you are somewhere around at that time, you are welcome to join. Please find below a short summary written by Safaa. You can also read more on Safaa’s work by downloading her papers on (i) “Disjunct populations of European vascular plant species keep the same climatic niches” and (ii) “Ecological niche shifts of understorey plants along a latitudinal gradient of temperate forests in north-western Europe“, both published in Global Ecology and Biogeography.

Ecological niche under climate change: conservatism and role in the biodiversity-ecosystem functioning relationship

Abstract: The scientific literature has shown a revival of interest in the concept of the ecological niche for the recent decades. This interest was largely promoted by the increasing use of species distribution models (SDMs) to inform conservation and management strategies in relation to climate change. In this thesis, I studied and used the concept of the ecological niche to answer two research questions which are heavily debated in ecology: the niche conservatism hypothesis and the relationship between biodiversity and ecosystem functioning. The first part of my work provides the first large-scale (i.e. Europe) assessment of the niche conservatism hypothesis between distinct populations of the same species and for a large number of vascular plant species (389 species) in their native geographical range. Main results from this work suggest that niche conservatism of vascular plant species is a widespread phenomenon. However, we also found that regional differences in niche width and optimum are common suggesting that other processes including adaptive responses are at play. Hence, while we conclude positively on the legitimacy of SDMs for predicting future species distributions, our results nevertheless show the importance of considering regional variations in the key parameters of species’ realized niche (cf. niche width and optimum) as well as the key mechanisms governing them (e.g. local adaptation), in order to accurately predict how these regional subtleties within the ecological space translate into the geographical space. In the second part of my thesis, I incorporated the concept of the ecological niche into the relationship between biodiversity and the net production of aboveground biomass in understory plant communities of temperate deciduous forests in Northern France. For this purpose, we first built a new set of diversity indices capturing the idea of ecological-niche diversity and then used it as an alternative or a complementary facet of biodiversity to test its relative importance for standing biomass in comparison with other facets of biodiversity that are more commonly used in ecology (cf. taxonomic and functional diversity). Among other things, results from this work highlight the importance of considering the ecological niche of species (sensu Hutchison) as an alternative and complementary facet of biodiversity having an important impact on ecosystem functioning, particularly the net production of aboveground biomass within the forest herb layer. These new findings suggesting a strong niche conservatism and supporting the idea to use the concept of the ecological niche as a facet of biodiversity will improve our understanding and our predictions of the effect of climate change on biodiversity and therefore on ecosystem functioning.

Keywords: community ecology, ecological niche, climate change, niche conservatism, biodiversity, vascular plants, forest.

Supervisors: Dr. Jonathan Lenoir & Prof. Guillaume Decocq, UR “Ecologie et dynamique des systèmes anthropisés” (Edysan, FRE 3498 CNRS), Jules Verne University of Picardie.

Exam committee: Prof. Antoine Guisan, Department of Ecology & Evolution, University of Lausanne; Prof. Martin Diekmann, Institute of Ecology, University of Bremen; Prof. Jean-Claude Gégout, UR “Laboratoire d’étude des resources forêts bois” (UMR 1092 LERFoB), AgroParisTech-ENGREF.

Importance du Concept de Niche Ecologique en Contexte de Changement Climatique

Je suis fier d’annoncer que Safaa Wasof, étudiante en thèse à l’Université de Picardie Jules Verne (UPJV) dans l’unité de recherche “Ecologie et dynamise des systèmes anthropisés” (Edysan, FRE3498 CNRS-UPJV), soutiendra sa thèse publiquement le 27 Novembre prochain, à 9H00, en salle des thèses de la Faculté de pharmacie (Pôle Santé Saint Charles : 1 rue des Louvels, 80037 Amiens Cedex 1). Si vous êtes de passage dans les environs vous êtes la/le bienvenu(e). Ce fût un réel plaisir pour moi de travailler aux côtés de Safaa durant ces quatre dernières années (Octobre 2011 – Octobre 2015) et de co-encadrer son travail de thèse dont vous trouverez un résumé écrit par Safaa ci-dessous. Vous trouverez également plus d’informations sur les travaux de Safaa en lisant ses articles intitulés (i) “Disjunct populations of European vascular plant species keep the same climatic niches” et (ii) “Ecological niche shifts of understorey plants along a latitudinal gradient of temperate forests in north-western Europe“, tout deux publiés dans la revue Global Ecology and Biogeography.

La niche écologique en contexte de changement climatique : conservatisme et rôle dans la relation biodiversité-fonctionnement de l’écosystème

Résumé : Ces dernières décennies le concept de niche écologique a connu un véritable regain d’intérêt dans la littérature scientifique. Cet intérêt a été largement promu par l’utilisation croissante des modèles de distribution d’espèces (SDMs) pour informer sur les défis de conservation et de gestion liés aux changements globaux. Dans cette thèse, j’ai étudié et utilisé ce concept de niche écologique pour répondre à deux questions de recherches faisant l’objet d’importants débats en écologie : le conservatisme de la niche écologique et la relation entre biodiversité et fonctionnement de l’écosystème. Le premier volet de mes travaux a ainsi fournit une première estimation globale de l’hypothèse de conservation de la niche entre des populations distinctes de la même espèce et ce chez un grand nombre d’espèces vasculaires (389 espèces) dans leur aire géographique d’indigénat. Cette partie a permis de mettre en évidence que le conservatisme de la niche climatique réalisée est un phénomène répandu. Toutefois, des différences régionales dans les paramètres synthétiques de la niche (cf. l’amplitude et l’optimum de la niche) étaient fréquentes laissant la possibilité d’une adaptation locale potentielle des populations végétales au sein de chaque région. Ces résultats renforcent la légitimité des SDMs, mais ils montrent néanmoins l’importance de considérer les variations régionales de l’amplitude et de l’optimum de la niche réalisée des espèces, ainsi que les mécanismes clés qui les régissent (comme l’adaptation locale), dans les prédictions des SDMs quand il s’agit de traduire ces subtilités régionales dans l’espace géographique. Dans le deuxième volet de ma thèse, je me suis ensuite intéressée à utiliser le concept de niche écologique au service de l’étude de la relation entre biodiversité et un aspect particulier du fonctionnement des écosystèmes : la production nette de biomasse aérienne au sein de la strate herbacée forestière. Nous avons pour cela développé et intégré, pour la première fois, la notion de diversité des niches écologiques comme facette alternative ou complémentaire de la biodiversité et avons comparé son importance vis-à-vis des autres facettes de la biodiversité utilisées plus communément en écologie (cf. diversité taxonomique et fonctionnelle). Entre autres choses, cette partie a permis de démontrer l’importance de considérer la niche écologique des espèces (sensu Hutchison) en tant que facette de la biodiversité ayant un rôle important dans le fonctionnement de l’écosystème, plus particulièrement la production nette de biomasse aérienne des communautés végétales du sous-bois forestier. Dans un contexte de changement climatique, évaluer et étudier les conséquences éventuelles d’un degré élevé de conservatisme de la niche vis-à-vis des conditions climatiques sur la distribution des espèces et donc sur la biodiversité, ainsi que de comprendre la relation entre biodiversité et le fonctionnement de l’écosystème sont deux étapes incontournables pour améliorer notre compréhension ainsi que nos prédictions de l’effet du changement climatique sur la biodiversité et donc sur le fonctionnement des écosystèmes.

Mots-clés : biomasse, biodiversité, changement climatique, conservation de la niche, écologie des communautés, écologie fonctionnelle, écologie végétale, écosystème forestier, niche écologique, plantes vasculaires, productivité.

Encadrants : Dr. Jonathan Lenoir & Prof. Guillaume Decocq, UR “Ecologie et dynamique des systèmes anthropisés” (Edysan, FRE 3498 CNRS), Université de Picardie Jules Verne.

Membres du jury : Prof. Antoine Guisan, Department of Ecology & Evolution, University of Lausanne; Prof. Martin Diekmann, Institute of Ecology, University of Bremen; Prof. Jean-Claude Gégout, UR “Laboratoire d’étude des resources forêts bois” (UMR 1092 LERFoB), AgroParisTech-ENGREF.

A Call for a Post-Doc Position in Ecoinformatics and Vegetation: Combining Remote Sensing and Field Data in a Toolbox to Map Non-Native Plant Distribution

Project aim:


Saplings of Prunus seronita, a non-native plant, in a mixed Oak-Beech forest stand in Compiègne (France)

This postdoctoral position is part of a BiodivERsA project entitled “Detection of invasive plant species and assessment of their impact on ecosystem properties through remote sensing (DIARS)”. By combining field data together with two aircraft remote sensing technologies (hyperspectral imaging and light detection-and-ranging), DIARS aims at monitoring and modelling spread and risk assessment of invasive plant species at fine spatial resolution. Both remote sensing and field data are already available within the DIARS consortium for three different study sites (Belgium, France and Germany). The postdoc will develop a toolbox in a Free and Open Source environment (cf. R or GRASS GIS) to help end-users to combine both remote sensing and field data in a modelling framework that will allow mapping the invasion dynamic of non-native plants. More specifically, the toolbox will handle hyperspectral data preprocessing and classification, LiDAR data processing, species distribution modeling based on spatial proxies as well as field occurrences, and spatial representation of the uncertainty related to statistical modeling procedures. There will be many opportunities for independent and collaborative research in related areas of ecoinformatics.


Canopy density derived from LiDAR data at 50-cm resolution across the entire Compiègne forest (144 km2) in northern France (Tarek Hattab)

The candidate is expected to have the following qualifications:

  • A Ph.D. in environmental sciences, computer sciences, statistics or mathematics;
  • Cutting-edge expertise in modeling and advanced statistical analyses;
  • Coding skills in Free and Open Source environments (R or GRASS GIS);
  • Basic knowledge and interest in plant ecology and biological invasions;
  • Experience in remote sensing;
  • Strong collaborative skills;
  • Proven abilities to publish at a high International level;
  • Good oral and written communication skills in English;
  • Ability to self-manage European project under European Commission, e.g. FP7.

Supervisors and collaborators:

The main supervisors are Dr. Jonathan Lenoir and Dr. Duccio Rocchini who are Associate Professor in Biostatistics and Researcher in Geographical Modeling and Spatial Ecology, respectively. The postdoc will work in close collaboration with Tarek Hattab, who is a Post-Doctoral fellow involved in DIARS, and will benefit from interactions with researchers in remote sensing (Dr. Ben Somers, Dr. Feilhauer Hannes, Prof. Sebastian Schmidtlein and Prof. Gregory Asner), conservation ecology (Prof. Olivier Honnay) and biological invasions (Prof. Guillaume Decocq).


Ecologie et Dynamique des Systèmes Anthropisés (EDYSAN), Jules Vernes University of Picardie, Amiens, France. EDYSAN is a young, diverse, vibrant and international research community with strong collaborative interdisciplinary ties within and beyond Amiens. More information about the people and research activities of the group can be here.


The postdoctoral position should start at the latest on January 1st 2016. For further information, please contact: Dr. Jonathan Lenoir (


One year

Net salary:

2 100 EUR/month

Application deadline:

Please send your CV, including a list of publications, together with a cover letter and the contact information of 3 references to Jonathan Lenoir ( The application deadline is November 23rd 2015.

DIARS is funded by the ERA-Net BiodivERsA, with the national funders BelSPO,
DFG and ANR, part of the 2012-2013 BiodivERsA call for research proposals.