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New paper: Tree biomass reconstruction shows no lag in post-glacial afforestation of eastern Canada

Notre nouveau papier avec Julie Aleman est publié sur le site du Canadian Journal of Forest Research: Just-IN articles

Les données sont disponibles via une application web ici.

Citation: Blarquez O. and J. Aleman. Tree biomass reconstruction shows no lag in post-glacial afforestation of eastern Canada. Canadian Journal of Forest Research. DOI: 10.1139/cjfr-2015-0201

Abstract: Forest ecosystems in eastern Canada are particularly sensitive to climate change and may shift from carbon sinks to carbon sources in the coming decades. Understanding how forest biomass responded to past climate change is thus of crucial interest. But past biomass reconstruction still represents a challenge. Here we used transfer functions based on modern pollen assemblages and remote sensed biomass estimation to reconstruct and quantify, for the last 14 000 years, tree biomass dynamics for the six main tree genera of the boreal and mixed-wood forests (Abies, Acer, Betula, Picea, Pinus, Populus). We compared the mean genera and total biomass to climatic (summer temperatures and annual precipitation), physical (CO2, insolation, ice area) and disturbance (burned biomass) variables, to identify the potential drivers influencing the long-term trends in tree biomass. Tree biomass was for most genera related with summer temperature, insolation and CO2 levels; Picea was the exception and its biomass also correlated with annual precipitation. At the onset of the Holocene and during the Holocene Thermal Maximum c. 10000-6000 BP), tree biomass tracked the melting of the Laurentide Ice sheet with high values (>50 t.ha-1 and a total of 12 Pg). These values, in the range of modern forest ecosystems biomass, indicate that trees were probably able to survive in a periglacial environment and to colonize the region without any discernible lag by tracking the ice retreat. High biomass at the beginning of the Holocene was likely favoured by higher than present insolation, CO2 levels higher than during the Last Glacial Maximum, and temperature and precipitation close to present day levels. Past tree biomass reconstruction thus brings novel insights about the drivers of postglacial tree biomass and the overall biogeography of the region since the deglaciation.

Fig6-01

Legend: Temporal trend of mean genera biomass compared to climatic and physical variables. (a) Mean tree genera biomass temporal trends obtained by fitting a LOWESS (with a 200 years half window width) on reconstructed biomass from all sites. (b) Total biomass in 1000 years windows obtained by calculating the total biomass for each genera in each 50 $*$ 50 km pixel and then summing all pixel values within the studied territory. Total biomass values were expressed as petagrams (Pg) for convenience. (c) Biomass burning trend obtained by the analysis of charcoal series contained in the Global Charcoal Database. (d) Laurentide ice sheet area trend from (Dyke 2004). (e) NGRIP d18O record (grey line) and trend evaluated using 1000 years windows averages (plain red line). (f) Epica Dome C CO2 from (Monnin et al. 2004). Summer (june, july, august) temperatures (g) and annual precipitation (h) anomalies from the HadCM3 and CCSM3 GCM experiments. (i) Summer (JJA) insolation anomalies at 45° N.

QSR-113x150

New paper: 7000-year human legacy of elevation-dependent European fire regimes

Paper Highlights:
• 18 southern European charcoal records document 16,000 years of fire regime changes.
• Since the Neolithic, land uses have artificially maintained high fire frequencies.
• Human-induced decreases in forest cover led to a reduction in the biomass burned.
• Human-modified landscapes affected ecological processes more meaningly than expected.

Citation:

Vannière B., Blarquez O., Rius D., Doyen E., Brücher T., Colombaroli D., Connor S., Feurdean A., Hickler T., Lemmen C., Leys B., Massa C., Olofsson J. 2015. The human legacies of elevation-dependant European fire regimes. Quaternary Science Reviews. DOI: doi:10.1016/j.quascirev.2015.11.012.

Fig2

Fire regime proxy series through time (Fig. S1, S2 and S3). Density distribution of Charcoal Accumulation Rate Z-scores (CHAR), biomass burned and fire frequency proxies for all sites (a to c), for lowland sites (d to f), midland sites (g to i) and highland sites (j to l). The color scale translates the density of the proxy site-records at each time step; cold colors are indicative of data dispersion and thus capture the heterogeneity among sites; hot colors indicate site response homogeneity and thus spatial uniformity. The white dotted lines separate time periods with significant differences in the proxies’ mean and variance (see Materials and Methods). All ages are expressed in calibrated kilo-years Before the Present (conventionally fixed at 1950 AD).

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PhD opportunity in peatland ecology

The biogeography (https://udembiogeo.wordpress.com/) and paleogeography (http://blarquez.com/) labs at Université de Montréal are seeking a Ph.D. student to work on the impact of fire and other disturbances on long-term peat accumulation in northern peatlands using a mix of paleoecological and modeling approaches. The candidate will need to have a strong background in peatland ecology, paleoecology or ecosystem modeling. The position is funded but preference will be given to students with a high potential to secure external funding. Start date: September 1, 2016 or before.

To learn more about Université de Montréal, visit https://admission.umontreal.ca/en/student-info/.
Please send a CV, a statement of interest, transcripts and the contact information of at least 2 referees to Prof. Julie Talbot, (j.talbot@umontreal.ca) or Prof. Olivier Blarquez (olivier.blarquez@umontreal.ca).

Projet de doctorat en écologie des tourbières

Les laboratoires de biogéographie (https://udembiogeo.wordpress.com/) et paléogéographie (http://blarquez.com/) de l’Université de Montréal sont à la recherche de candidatures pour un projet de doctorat concernant l’impact des feux et autres perturbations sur l’accumulation à long terme de la tourbe dans les tourbières nordiques et ce, en utilisant des techniques paléoécologiques et de modélisation. Le candidat devra avoir de bonnes connaissances en écologie des tourbières, en paléoécologie ou en modélisation des écosystèmes. L’offre comprend une bourse, mais la priorité sera donnée aux étudiants ayant un bon potentiel pour se mériter une bourse externe. Début : 1 septembre 2016 ou avant.

Pour en apprendre plus sur le programme de doctorat en géographie à l’Université de Montréal, consulter http://geographie.umontreal.ca/programmes-cours/cycles-superieurs/doctorat-geographie/.
Envoyez votre CV, une lettre de motivation, des relevés de notes et les coordonnées d’au moins 2 références à Julie Talbot (j.talbot@umontreal.ca) ou Olivier Blarquez (olivier.blarquez@umontreal.ca)

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Source

ABC platform

We are pleased to share the design of a coring platform we developed with Julie Aleman. The criteria we used for the conception were affordability, the ability to find materials for the construction worldwide, high stability and simplicity. The platform was primarily designed for manipulating Kajak-Brinkhurst, Livingstone or Russian corers, and we were able to recover more than six meters of sediment under 9.5 m of water. We tested and constructed the platform in different countries (Republic of Congo, Tanzania and Québec, Canada) and in different environments (rivers, delta and lakes). Please fell free to modify and adapt the plans notably for different coring equipments. Let us know if the design has been useful to you by sending a photo. Happy coring!

ABCplatform.pdf

Projet de doctorat sur la réponse des forêts boréales aux changements environnementaux: approche paléoécologique des états de référence dans la pessière à mousses de l’Ouest du Québec

English follows

Contexte :

La forêt boréale constitue une ressource naturelle importante pour l’économie Québécoise. Au cours des dernières décennies, un écart s’est créé entre les paysages naturels et les paysages aménagés par l’homme. Par ailleurs les changements climatiques en cours modifient le régime des incendies et par voie de conséquence la composition et la structure de la végétation. Dans un contexte d’aménagement écosystémique de la forêt boréale il est important de connaître les états de référence pour les végétations et perturbations naturelles dans le passé afin d’estimer dans quelle mesure les végétations seront résilientes aux changements futurs. Nous recherchons un(e) étudiant(e) de doctorat qui travaillera sur la caractérisation de l’évolution de la composition forestière, en lien avec le feu et le climat, durant l’Holocène (11 000 ans) pour la pessière à mousses de l’Ouest du Québec. Une partie du projet de doctorat consistera à comparer la variabilité écosystémique future (définie par modélisation) avec celle du passé.

Le ou la candidat(e) aura à utiliser les outils de la paléoécologie (analyse de bio-indicateurs sédimentaires), de la cartographie historique, et réalisera des analyses spatiales afin de comparer les végétations et régimes d’incendies avec les enregistrements sédimentaires. Nous recherchons un candidat qui sera en mesure de réaliser des analyses statistiques avancées dans le but de calibrer les enregistrements paléoécologiques avec des données a
ctuelles. La calibration des enregistrements sédimentaires constitue une des originalités du projet, c’est une étape capitale qui permettra de mieux quantifier les changements et la variabilité écosystémique passée en des unités qui soient compatibles avec les divers scénarios pour le futur.

Le ou la candidat(e) choisi(e) sera sous la direction d’Olivier Blarquez (Département de Géographie, Université de Montréal) et de Pierre Grondin (Ministère des forêts, de la faune et des parcs (MFFP)). Le projet de doctorat s’inscrit dans un projet plus large visant à quantifier selon différentes approches la variabilité et les états de référence pour la pessière à mousse au Québec. A ce titre le ou la candidat(e) bénéficiera d’un réseau de collaboration enrichissant et devra réaliser une partie de ses travaux en collaboration avec des entreprises privées leaders de l’industrie forestière au Québec ainsi que le Ministère des forêts, de la faune et des parcs (MFFP) chargé de l’élaboration des états de référence.

Profil recherché :

Maitrise en géographie, biologie ou domaine connexe. La priorité sera donnée aux candidats ayant une expérience en analyse statistique et/ou SIG et/ou modélisation et/ou paléoécologie. Excellence académique, bonne capacité de rédaction et intérêt à publier les résultats de recherche.

Nous recherchons en priorité un candidat au doctorat, cependant les candidats ayant obtenu une thèse dans le domaine de la paléoécologie ou un domaine connexe, démontrant un très fort intérêt pour les approaches quantitatives et présentant un excellent dossier universitaire sont invités à postuler.

Postuler : Afin de postuler envoyer une lettre de motivation, un cv, un relevé de notes récent ainsi que le nom de trois référents à olivier.blarquez@umontreal.ca et Pierre.Grondin@mffp.gouv.qc.ca. Les candidatures seront examinées immédiatement et ce jusqu’à ce qu’un candidat soit choisi.

 

PhD project on the response of boreal forests to environmental change: a paleoecological approach to reference conditions in the spruce-moss domain in western Quebec. 

Context:

The boreal forest constitutes an important natural resource for the Quebec economy. In recent decades, a gap has emerged between natural and managed landscapes. Moreover, ongoing climate change is expected to alter fire regimes and consequently ecosystem composition and structure. In the context of sustainable management of the boreal forest it is essential that references conditions for vegetation and natural disturbances in the past be established, in order to estimate the resilience of vegetation in response to future changes. We are seeking a doctoral student to work on the characterization of changes in forest composition in response to fire and climate during the Holocene (11,000 years BP) for the spruce-moss domain in western Quebec. Part of the PhD project will focus on comparing future ecosystem variability (defined by modeling) with that of the past.

The candidate will perform paleoecological analysis and interpretation (analysis of sedimentary bio-proxies), historical mapping, and spatial analysis to compare vegetation and fire regimes with recent sedimentary records. We seek a PhD student to apply advanced statistical analysis to calibrate sedimentary records using survey data. The calibration of sedimentary records is an original characteristic of this project and represents a critical step that will make it possible to quantify past ecosystem variability more precisely in units compatible with the various scenarios for the future.

The successful candidate will be supervised by Dr. Olivier Blarquez (Department of Geography, University of Montreal) and Dr. Pierre Grondin (Ministry of Forestry, Wildlife and Parks – Ministère des forêts, de la faune et des parcs (MFFP)). The PhD project is part of a larger project that aims at quantifying the ecosystem variability of the spruce-moss domain in Quebec according to different approaches. For this reason, the student will be part of a research network and will conduct some of his/her work in collaboration with private companies that are leaders in the Quebec forestry industry, and the Ministry of Forestry, Wildlife and Parks (MFFP).

Training and skills:

MSc in geography, biology or a related field. Applicants with experience in statistical analysis and / or GIS and / or modeling and / or paleoecology will be given priority. Academic excellence, good writing skills and interest in publishing research results.

While priority will be given to a PhD candidate, applicants with a PhD in paleoecology or a related field who have demonstrated a strong interest in quantitative approaches and have an excellent academic record will also be considered.

Application:

To apply, send a cover letter, CV, recent transcript and the names of 3 referees to olivier.blarquez@umontreal.ca and Pierre.Grondin@mffp.gouv.qc.ca. Applications will be considered immediately and until the position is filled.

paleofire 1.1.5

A new version of the R package paleofire is available on CRAN at http://cran.r-project.org/web/packages/paleofire/index.html

This release includes a new vignette on the basic usage of paleofire for reconstructing regional charcoal composite curves and a new function to easily export GCD sites to Google Earth .kml file.

Screen Shot 2014-12-01 at 3.28.06 PM

The australasian sites above have been exported using:

library(paleofire)
x=pfSiteSel(id_region=="AUST")
require(sp)
pfToKml(x, file='/Users/Olivier/Desktop/sites.kml')

 

 

New paper: paleofire: an R package to analyse sedimentary charcoal records from the Global Charcoal Database to reconstruct past biomass burning

I am  pleased to announce the publication of a new study in Computers and Geosciences with Boris Vannière, Jennifer Marlon, Anne-Laure Daniau, Mitch Power, Simon Brewer and Patrick Bartlein. The paper is freely available online here until October 19 and soon as a package vignette for paleofire.

 

Paper highlights:
• We present the open source paleofire R package for analysis of sedimentary charcoal series.
• The package is used to analyse charcoal records from the Global Charcoal Database.
• The functions eases the steps for interrogating data contained within the GCD.
• Analyses included charcoal series transformation (homogenization) and synthesis.
• We describe paleofire by producing a regional synthesis of biomass burning in NE America.

paleofire package highlighted in the PAGES Magazine

The paleofire package has been highlighted in the April issue of the PAGES Magazine :

PAGES_April2014Vannière B., O. Blarquez, J. Marlon, A.-L. Daniau and M. Power. 2014. Multi-Scale Analyses of fire-climate- Vegetation Interactions on Millennial Scales. PAGES Magazine, Volume 22, Page 40.

The article presents the workshop of the Global Paleofire Working Group held in Frasne (France) on 2-6 October 2013 that was supported by PAGES. The pdf of the article can be downloaded here or directly from the PAGES website.

New paper: Disentangling the trajectories of alpha, beta and gamma plant diversity of North American boreal ecoregions since 15,500 years

I am  pleased to announce the publication of a new study in Frontiers in Ecology and Evolution with Christopher Carcaillet, Thibaut Frejaville and Yves Bergeron. The paper is freely available online here.

Assessment of biodiversity in a changing world is a key issue and studies on the processes and factors influencing its history at relevant time scales are needed. In this study, we analysed temporal trends of plant diversity using fossil pollen records from the North American boreal forest-taiga biome (NABT). We selected 205 pollen records spanning the last 15,500 years. Diversity was decomposed into α and γ richness, and β diversity, using Shannon entropy indices. We investigated temporal and spatial patterns of β diversity by decomposing it into independent turnover (variation in taxonomic composition due to species replacements) and nestedness (variation due to species loss) components. The palynological diversity of the NABT biome experienced major rearrangements during the Lateglacial and early Holocene in response to major climatic shifts. The β nestedness likely reflected plant immigration processes and generally peaked before the β turnover value, which mirrors spatial and temporal community sorting related to environmental conditions and specific habitat constraints. Palynological diversity was generally maximal during the Lateglacial and the early Holocene and decreased progressively during the Holocene. These results are discussed according to macro-ecological processes, such as immigration, disturbances and environmental fluctuations, with climate most notably as the main ecological driver at millennial scales.