Eric Marcon

Eric Marcon

Senior Researcher in Ecology

AgroParisTech

Biography

I am a researcher in Tropical Ecology with UMR Amap, a professor at AgroParisTech and a coordinator of the BioGET course of the Biodiversity, Ecology and Evolution master’s degree at AgroParisTech and Montpellier University.

Interests
  • Community Ecology
  • Tropical Forestry
  • Ecological Statistics
  • R development
Education
  • Habilitation à Diriger des Recherches (French qualification to supervise research) in Ecology, 2016

    University of French Guiana

  • PhD in Ecology, 2010

    AgroParisTech

  • Post-Graduate Engineering School of Public Administration, 1999

    Ecole Nationale du Génie Rural, des Eaux et des Forêts

  • MSc in International Economics, 1999

    University of Paris I, Panthéon Sorbonne

  • Graduate Engineering School of Forestry, 1990

    Ecole Nationale des Ingénieurs des Travaux des Eaux et Forêts

Experience

 
 
 
 
 
AgroParisTech
Head of the Joint Research Unit Ecology of Guianan Forests (UMR EcoFoG
January 2010 – August 2020 Kourou, French Guiana

Responsibilities included:

  • Administration of research
  • Management
  • Teaching (graduate and post-graduate students)
  • Research

Recent Publications

Effect of climate on traits of dominant and rare tree species in the world's forests

Species’ traits and environmental conditions determine the abundance of tree species across the globe. The extent to which traits of dominant and rare tree species differ remains untested across a broad environmental range, limiting our understanding of how species traits and the environment shape forest functional composition. We use a global dataset of tree composition of >22,000 forest plots and 11 traits of 1663 tree species to ask how locally dominant and rare species differ in their trait values, and how these differences are driven by climatic gradients in temperature and water availability in forest biomes across the globe. We find three consistent trait differences between locally dominant and rare species across all biomes; dominant species are taller, have softer wood and higher loading on the multivariate stem strategy axis (related to narrow tracheids and thick bark). The difference between traits of dominant and rare species is more strongly driven by temperature compared to water availability, as temperature might affect a larger number of traits. Therefore, climate change driven global temperature rise may have a strong effect on trait differences between dominant and rare tree species and may lead to changes in species abundances and therefore strong community reassembly.

Local Forest Structure and Host Specificity Influence Liana Community Composition in a Moist Central African Forest

Lianas are important components of tropical forest diversity and dynamics, yet little is known about the drivers of their community structure and composition. Combining extensive field and LiDAR data, we investigated the influence of local topography, forest structure, and tree composition on liana community structure, and their floristic and functional composition, in a moist forest in northern Republic of Congo. We inventoried all lianas ≥ 1 cm in diameter in 144 20 × 20‐m quadrats located in four 9‐ha permanent plots, where trees and giant herbs were inventoried. We characterized the functional strategies of selected representatives of the main liana taxa using a set of resource‐use leaf and wood traits. Finally, we used complementary statistical analyses, including multivariate and randomization approaches, to test whether forest structure, topography, and tree composition influence the structure, floristic composition, and functional composition of liana communities. The structure of liana communities was strongly shaped by local forest structure, with higher abundances and total basal areas in relatively open‐canopy forests, where lianas competed with giant herbs. Liana floristic composition exhibited a weak spatial structure over the study site but was marginally influenced by the local forest structure and topography. Only forest structure had a weak but significant effect on liana functional composition, with more conservative strategies—higher stem tissue density and lower PO4 leaf concentration and SLA values—in tall and dense forests. Finally, we found evidence of host specificity with significant attraction/repulsion for 19% of the tested liana and tree species associations, suggesting that the unexplained floristic variation may be partly attributed to these host‐species‐specific associations, although the underlying mechanisms behind remain elusive. Overall, our findings demonstrate that liana communities’ structure can be much better predicted than their composition, calling for a better understanding of the implications of the large functional diversity observed in liana communities.

Dissecting earthworm diversity in tropical rainforests

Tropical rainforests are among the most emblematic ecosystems in terms of biodiversity. However, our understanding of the structure of tropical biodiversity is still incomplete, particularly for certain groups of soil organisms such as earthworms, whose importance for ecosystem functioning is widely recognised. This study aims at determining the relative contribution of alpha and beta components to earthworm regional diversity at a hierarchy of nested spatial scales in natural ecosystems of French Guiana. For this, we performed a hierarchical diversity partitioning of a large dataset on earthworm communities, in which DNA barcode‐based operational taxonomic units (OTUs) were used as species surrogates. Observed regional diversity comprised 256 OTUs. We found that alpha diversity was lower than predicted by chance, regardless of the scale considered. Community‐scale alpha diversity was on average 7 OTUs. Beta diversity among remote landscapes was higher than expected by chance, explaining as much as 87% of regional diversity. This points to regional mechanisms as the main driver of species diversity distribution in this group of organisms with low dispersal capacity. At more local scales, multiplicative beta diversity was higher than expected by chance between habitats, while it was lower than expected by chance between communities in the same habitat. This highlights the local effect of environmental filters on the species composition of communities. The calculation of a Chao 2 index predicts that as many as 1700 species could be present in French Guiana, which represents a spectacular increase compared with available checklists, and calls into question the commonly accepted estimates of global number of earthworm species.

The global distribution and drivers of wood density and their impact on forest carbon stocks

The density of wood is a key indicator of the carbon investment strategies of trees, impacting productivity and carbon storage. Despite its importance, the global variation in wood density and its environmental controls remain poorly understood, preventing accurate predictions of global forest carbon stocks. Here we analyse information from 1.1 million forest inventory plots alongside wood density data from 10,703 tree species to create a spatially explicit understanding of the global wood density distribution and its drivers. Our findings reveal a pronounced latitudinal gradient, with wood in tropical forests being up to 30% denser than that in boreal forests. In both angiosperms and gymnosperms, hydrothermal conditions represented by annual mean temperature and soil moisture emerged as the primary factors influencing the variation in wood density globally. This indicates similar environmental filters and evolutionary adaptations among distinct plant groups, underscoring the essential role of abiotic factors in determining wood density in forest ecosystems. Additionally, our study highlights the prominent role of disturbance, such as human modification and fire risk, in influencing wood density at more local scales. Factoring in the spatial variation of wood density notably changes the estimates of forest carbon stocks, leading to differences of up to 21% within biomes. Therefore, our research contributes to a deeper understanding of terrestrial biomass distribution and how environmental changes and disturbances impact forest ecosystems.

Dominance and rarity in tree communities across the globe: Patterns, predictors and threats

  • Aim: Ecological and anthropogenic factors shift the abundances of dominant and rare tree species within local forest communities, thus affecting species composition and ecosystem functioning. To inform forest and conservation management it is important to understand the drivers of dominance and rarity in local tree communities. We answer the following research questions: (1) What are the patterns of dominance and rarity in tree communities? (2) Which ecological and anthropogenic factors predict these patterns? And (3) what is the extinction risk of locally dominant and rare tree species? Location Global.
  • Time period: 1990-2017.
  • Major taxa studied: Trees.
  • Methods: We used 1.2 million forest plots and quantified local tree dominance as the relative plot basal area of the single most dominant species and local rarity as the percentage of species that contribute together to the least 10% of plot basal area. We mapped global community dominance and rarity using machine learning models and evaluated the ecological and anthropogenic predictors with linear models. Extinction risk, for example threatened status, of geographically widespread dominant and rare species was evaluated.
  • Results: Community dominance and rarity show contrasting latitudinal trends, with boreal forests having high levels of dominance and tropical forests having high levels of rarity. Increasing annual precipitation reduces community dominance, probably because precipitation is related to an increase in tree density and richness. Additionally, stand age is positively related to community dominance, due to stem diameter increase of the most dominant species. Surprisingly, we find that locally dominant and rare species, which are geographically widespread in our data, have an equally high rate of elevated extinction due to declining populations through large-scale land degradation.
  • Main conclusions: By linking patterns and predictors of community dominance and rarity to extinction risk, our results suggest that also widespread species should be considered in large-scale management and conservation practices.

Software

memoiR
memoiR is an R package that provides templates to publish well-formatted documents both in HTML and PDF formats. Documents can be produced locally or hosted on GitHub, where GitHub actions can update the published documents continuously.
dbmss
dbmss is an R package for simple computation of spatial statistic functions of distance to characterize the spatial structures of mapped objects, including classical ones (Ripley’s K and others) and more recent ones used by spatial economists (Duranton and Overman’s Kd, Marcon and Puech’s M).
Entropart
entropart is an R package that provides functions to calculate $\alpha$, $\beta$ and $\gamma$ diversity of communities, including phylogenetic and functional diversity. Estimation-bias corrections are available.

Courses

Species Abundance Distributions
No other general attribute of ecological communities besides species richness has commanded more theoretical and empirical attention than relative species abundance (Hubbell, 2001). The aim of the course is to understand the main abundance distributions, master the different representations and understand area-species relationships, at different scales.
Measurement of Biodiversity
The original definition of biodiversity is the number of species in a community. It has been extended in many ways, often using ad-hoc indices. This course introduces a unified approach to measuring biodiversity, based on information theory, which allows biodiversity to be described as an effective number of categories (usually species) corresponding to the question at hand: taxonomic diversity when all species are considered equivalent, phylogenetic diversity when their evolutionary proximity is taken into account, and functional diversity when the distance between pairs of species does not fit into a tree.
Forest Dynamics
This course is dedicated to the students of the joint Master’s program Global Forestry. It is an introduction to the dynamics of tropical forests. The objectives are to: Be able to describe the state and dynamics of a forest.

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