50th lab paper! The LAST Coring Platform You Will Ever Need: Light, Affordable, Stable, and Transportable

We are very happy to share this technical note about our lab coring platform design published recently in Quaternary: Blarquez O. and Aleman J. C. 2020. The LAST coring platform you will ever need: Light, Affordable, Stable, and Transportable. Quaternary, 3, 27. https://doi.org/10.3390/quat3030027  

The paper is accessible in open access from the Quaternary website https://doi.org/10.3390/quat3030027 and the coring platform plan are available here: https://www.mdpi.com/2571-550X/3/3/27/s1 or here: quaternary-03-00027-s001

Abstract: Coring lakes and water bodies for paleoecological studies often involves using a coring platform to properly operate a sediment sampling device. In the past, coring platforms have been developed by specific paleoecology laboratories or by private companies. Those coring platforms are generally composed of two boats (inflatable boats, kayaks, etc.) connected together by a metallic and wood structure. While these coring platforms have proven their efficacy, they are not ideal in several coring settings requiring remote transportation, and their cost may be prohibitive for less funded paleoecological laboratories. On this technical note, we describe the Light, Affordable, Stable, and Transportable (LAST) coring platform. Coring platforms based on these principles and on the design presented herein have been extensively tested in various conditions and countries by our research group and collaborators. In the first part of this manuscript, we present the principles and the design of the LAST coring platform; then, we discuss the coring setting for which the LAST coring platform is suitable, and its possible limitations. Associated with this manuscript, we provide a construction and assemblage manual developed without words and with simple illustrations in order to make it easily accessible to speakers of any language. 



New paper: Paleolimnological assessment of wildfire‐derived atmospheric deposition of trace metal(loid)s and major ions to subarctic lakes (Northwest Territories, Canada)

I am very pleased to share this article by Nicolas Pelletier about fires and trace metal(loid)s in the Northwest Territories:

Pelletier N., Chételat J., Blarquez O., & Vermaire J. C. (2020). Paleolimnological assessment of wildfire‐derived atmospheric deposition of trace metal(loid)s and major ions to subarctic lakes (Northwest Territories, Canada). Journal of Geophysical Research: Biogeosciences, 125, e2020JG005720. https://doi.org/10.1029/2020JG005720

You can find the paper here https://doi.org/10.1029/2020JG005720 and here 

Plain language summary:

The subarctic boreal forest is facing major changes in fire regimes in response to climate change, and it is predicted that wildfires will become increasingly frequent and
severe in the near future. Wildfires release terrestrial elements to the atmosphere as aerosols, and the impact of ash fallout from local fires on metal(loid) deposition is not well characterized. Wildfire fallouts contain certain elements that can be essential to living organisms (e.g., Ca, Mg, Mn, and Fe) and others that can be toxic (e.g., Pb, Hg, Cd, and As). In this research, we used lake sediment to estimate the amount of material deposited by wildfires in lakes of the subarctic boreal forest over the last 150 years. We found that the input of major ions (e.g., Na, Mg, Ca, and K), metals (e.g., Pb, Hg, Al, and Fe), and metalloids (As and Sb) was elevated during wildfire periods but only by a small amount. The impact of atmospheric deposition was observable in sediment records, indicating that element accumulation in lake sediment can be influenced by wildfires occurring outside the catchment. This study suggests that large areas, including many lakes, will receive additional metal, metalloid, and major ion inputs from more frequent wildfire fallout.

New paper: The reconstruction of burned area and fire severity using charcoal from boreal lake sediments

We are pleased to share the last lab paper by Andy Hennebelle: Hennebelle, A., Aleman, J. C., Ali, A. A., Bergeron, Y., Carcaillet, C., Grondin, P., Landry J. & Blarquez, O. (2020). The reconstruction of burned area and fire severity using charcoal from boreal lake sediments. The Holocene, 0959683620932979.

You can find the paper here https://doi.org/10.1177/0959683620932979 and here 

Although lacustrine sedimentary charcoal has long been used to infer paleofires, their quantitative reconstructions require improvements of the calibration of their links with fire regimes (i.e. occurrence, area, and severity) and the taphonomic processes that affect charcoal particles between the production and the deposition in lake sediments. Charcoal particles >150 µm were monitored yearly from 2011 to 2016 using traps submerged in seven head lakes situated in flat-to-rolling boreal forest landscapes in eastern Canada. The burned area was measured, and the above-ground fire severity was assessed using the differentiated normalized burn ratio (dNBR) index, derived from LANDSAT images, and measurements taken within zones radiating 3, 15, and 30 km from the lakes. In order to evaluate potential lag effects in the charcoal record, fire metrics were assessed for the year of recorded charcoal recording (lag 0) and up to 5 years before charcoal deposition (lag 5). A total of 92 variables were generated and sorted using a Random Forest-based methodology. The most explanatory variables for annual charcoal particle presence, expressed as the median surface area, were selected. Results show that, temporally, sedimentary charcoal accurately recorded fire events without a temporal lag; spatially, fires were recorded up to 30 km from the lakes. Selected variables highlighted the importance of burned area and fire severity in explaining lacustrine charcoal. The charcoal influx was thus driven by fire area and severity during the production process. The dispersion process of particles resulted mostly of wind transportation within the regional (<30 km) source area. Overall, charcoal median surface area represents a reliable proxy for reconstructing past burned areas and fire severities.

Researchers see need for action on forest fire risk

New statistical approach: changes in forest fires in the 19th and 20th centuries were man-made

How do humans affect forest fires? And what can we learn from forest fires in the past for the future of forestry? An international team of researchers led by Elisabeth Dietze, formerly at the German Research Centre for Geosciences GFZ in Potsdam and now at the Alfred Wegener Institute – Helmholtz Centre for Polar and Marine Research, now provides new answers to these questions. The research team has shown for a region in north-eastern Poland that forest fires increasingly occurred there after the end of the 18th century with the change to organised forestry. Among other things, the conversion of forests into pine monocultures played a role. The increased number of fires subsequently made it necessary to manage and maintain the forests differently. The researchers report on this in the journalPLOS ONE.

Every natural landscape has its own pattern of how fires behave there. This pattern is also known as the “fire regime”. Fire regimes are directly linked to the landscape, its vegetation and climate. Humans can change these regimes by managing a landscape. However, little is yet known about how they influenced fire regimes before the beginning of active forest fire fighting. Among the past 250 years, the human contribution to the global increase in fires during the mid- 19th century is particularly unclear, as the data available for this period is not comprehensive.

In the study published now, the researchers examined the extent to which forest management influenced the fire regime in a temperate forest landscape around Lake Czechowskie in the Bory Tucholskie (English:Tuchola Forest). Bory Tucholskie located in north-eastern Poland is one of the largest forest areas of Central Europe. The researchers combined evidence from various sources, such as pieces of charcoal and molecules formed during biomass combustion, so-called molecular fire markers. The investigated material originated from drilling cores of lake sediments. The researchers applied a new statistical approach to the classification of fires to their samples. They compared their measurements with independent climate and vegetation reconstructions and historical records.

Adaptation needs in the context of climate change

The team found two striking changes in the fire regime in the 19th and 20th centuries, both of which were driven by man. Accordingly, the amount of biomass burned unintentionally increased during the mid-19th century. At that time, the flammable, fast-growing pine monocultures necessary for industrialisation were planted.“After devastating fires in 1863, fire became an important factor in forest management,”explains Elisabeth Dietze.

At the end of the 19th century, state forestry reacted with an active fire prevention strategy. Various measures, such as a denser network of paths, were used to prevent fires. These measures had been very effective over the 20th century and the number of fires had decreased. But after the collapse of the Soviet Union, more pine trees were planted again in the 1990s. The forested area had increased.“In the course of climate change with its temperature rise and more frequent dry summers a new adjustment of forestry is necessary. Fires should be suppressed more effectively in the future and the forest should be restructured – towards more diverse and less flammable tree and shrub species. This is our most important result for forestry,”says Elisabeth Dietze.

With the new findings, models for predicting fires can be better calibrated.“We can reconstruct fire types more comprehensively than before,”says Elisabeth Dietze.“Even low-intensity fires, such as typical ground fires in contrast to crown fires, can be detected with molecular fire markers, which was not possible with charcoal alone.”

The study is a cooperation between scientists from the Netherlands and Canada and partners in ‘ICLEA – Virtual Institute for Integrated Climate and Landscape Development Analysis’. As partners the GFZ, the Ernst Moritz Arndt University Greifswald, the Brandenburg Technical University Cottbus together with the Polish Academy of Sciences bundle their research capacities and expertise to investigate the climate and landscape development of the historical cultural landscape between North East Germany and North West Poland.

Original study:
Dietze, E., Brykała,D., SchreuderL.T. et al., 2019. Human-induced fire regime shifts during 19thcentury industrialization: a robust fire regime reconstruction using northern Polish lake sediments.PLOS ONE. DOI: 10.1371/journal.pone.0222011


Sediments from Lake Czechowskie in the Tuchola Forest, Poland, allow for the high-resolution reconstruction of past forest fires in a region dominated by pine monocultures sensitive to the ongoing environmental change (Photo: D. Brykała, Polish Academy of Science).

Further information:

ICLEA – Virtual Institute of Integrated Climate and Landscape Evolution Analyses

New paper: Palaeo-trajectories of forest savannization in the southern Congo

I am pleased to share the last lab paper leaded by Julie Aleman: 

Julie C. Aleman, Olivier Blarquez, Hilaire Elenga, Jordan Paillard, Victor Kimpuni, Gaubin Itoua, Gauthier Issele, A. Carla Staver. 2019. Palaeo-trajectories of forest savannization in the southern Congo. Biology Letters. 15. http://doi.org/10.1098/rsbl.2019.0284 

The paper follows our 2015 fieldwork in the Republic of the Congo where we cored the Ngofouo lake:

Ngofouo lake.

Savanna surrounding the lake.

The ceremony before coring the lake.

Coring team.

Featured image: Savana fire burning near the forest edge in the Pool province in August 2015. 

Tropical savannah and forest are thought to represent alternative stable states in ecosystem structure in some climates. The implication is that biomes are maintained by positive feedbacks, e.g. with fire, and that historical distributions could play a role in determining modern ones. In this context, climate alone does not govern transitions between biomes, and understanding the causes and pathways of such transitions becomes crucial. Here, we use a multi-proxy analysis of a 2000-year core to evaluate modes of transition in vegetation structure and fire regimes. We demonstrate a first transition ca 1540 BP, when a cyclic fire regime entered a forested landscape, eventually resulting, by ca 1060 BP, in a transition to a more open savannah-like or mosaicked structure. This pattern may parallel currently accelerating fire regimes in tropical forests suggesting that fires can savannize forests, but perhaps more slowly than feared. Finally, ca 540 BP, a drought combined with anthropogenic influences resulted in a conclusive transition to savannah, probably resembling the modern landscape in the region. We show here that fire interacted with drought to transition forest to savannah, suggesting that disturbance by fire can be a major driver of biome change.

Analyseur pollinique Rapid-E

Dans le cadre du financement FCI SmartForests Canada nous venons d’acquérir un analyseur automatique de pollen Rapid-E développé par la société Plair (plus d’infos ici: http://www.plair.ch/Products%20RapidE.html). Les grains de pollen sont comptés et analysés par un laser qui permet d’acquérir des spectres de fluorescence qui sont propres à chaque espèce, des algorithmes d’intelligence artificielle permettent par la suite de déterminer les espèces.  L’appareil va nous permettre de suivre en temps réel et en continu la reproduction des espèces tempérées à la Station de Biologie des Laurentides (https://sbl.umontreal.ca/accueil/) où différentes expériences de suivi de la croissance des arbres, de transplantation et de suivi environnemental ont lieu dans le cadre de SmartForests Canada. L’appareil est enfin en fonction (merci aux ingénieurs de Plair!) et les données commencent à s’accumuler, à très bientôt pour les séries temporelles et plus d’informations sur l’équipement!

Temporal density of 14C dating

In this tutorial I illustrate the methods that have been used to reconstruct the curve of the temporal density of archeological dating around the Folly peat bog in Blarquez et al. (2018).

The approach is inspired by ‘clam’ package age-depth modeling (Blaauw, 2010). For each archeological dating, we will randomly pick one age according to its calibrated probability density (i.e., ages with a higher probability are more likely to be selected). We will then use a kernel density function to assess the temporal density of archeological dating. We will repeat this procedure 1000 times to assess the 95% confidence interval (CI) around the median trend in archeological sites dating during the Holocene.

In the original paper the archeological 14C dates came from the CARD database for sites that were located within a 200 km radius of Folly peat bog (Martindale et al., 2016), and wer completed with an additional set of 7 dates from an archeological site in Gatineau, which had yet to be included in the database (Archeotec, 2014). In this example we will simply simulate some 14C dating:

# rm(list=ls())

## Generate a random list of 14C dating --------------------------------------------------
age_14C=round(runif(100, 40, 500))*10
age_sd=round(runif(100, 2, 7))*10

We then calibrate each date in the database using the IntCal13 calibration curve (Reimer et al., 2013):

## Calibrate these dates using Bchron ---------------------------------------------------


Here we define a custom function that will be used to sample an age within each dates distribution. This sampling is done according to the probability density distribution of each age. This procedure is somewhat equivalent with clam and bacon sampling procedure.

## Sample one age with probability (equivalent to clam and ?bacon) -----------------------
## Use lapply to sample inside a list of ages

# Test a single iteration

Now we will run this sampling 1000 times and for each iteration we will reconstruct the density of calibrated ages using kernel density estimation with a bandwidth of 150 years. We will subsequently calculate the median density of ages and 95% confidence intervals.

n=length(age_14C) #number of events
age_=seq(100, 6000, 10); # adapt to your time frame

## Bootstrap --------------------------------------------------

for(i in 1:nbboot){
to=6000, n=length(age_))$y*n)
cat(i," ")

CI=apply(fmat, 1, quantile, probs=c(alpha/2,0.5,1-(alpha/2)) )

Plot the temporal trends in the density of archeological dating (along with max intercepts for each date sensu Telford et al. (2004), for display purpose only):

## Plot --------------------------------------------------------
df2=data.frame(x=mdates,y =0)

df=data.frame(age=age_, t(CI))
ylab("Dating density")+xlab("Age cal. BP")+

## --------------------------------------------------------------

Archéotec, 2014. Travaux de réaménagement de la rue Jacques-Cartier, ville de Gatineau Site BiFw-172,

Blaauw, M., 2010. Methods and code for “classical” age-modelling of radiocarbon sequences. Quaternary Geochronology, 5(5), pp.512–518. Available at: http://dx.doi.org/10.1016/j.quageo.2010.01.002.

Blarquez, O. et al., 2018. Late Holocene influence of societies on the fire regime in southern Québec temperate forests. Quaternary Science Reviews, 180, pp.63–74. Available at: http://linkinghub.elsevier.com/retrieve/pii/S0277379117307060 [Accessed December 15, 2017].

Martindale, A. et al., 2016. Canadian Archaeological Radiocarbon Database (CARD 2.1), accessed 15 September 2017. , 2004.

Reimer, P.J. et al., 2013. IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP. Radiocarbon, 55(04), pp.1869–1887. Available at: https://www.cambridge.org/core/product/identifier/S0033822200048864/type/journal_article.

Telford, R.J., Heegaard, E. & Birks, H.J.B., 2004. The intercept is a poor estimate of a calibrated radiocarbon age. The Holocene, 14(2), pp.296–298. Available at: http://journals.sagepub.com/doi/10.1191/0959683604hl707fa.

Letter: Glacial refugia in the south‐western Alps?

Find out our last letter in New Phytologist with Christopher Carcaillet: Glacial refugia in the south‐western Alps? a response to Finsinger et al. (2019) ‘Fire on ice and frozen trees? Inappropriate radiocarbon dating leads to unrealistic reconstructions. 

Your can download the pdf here  or on the revue website: http://doi.wiley.com/10.1111/nph.15673

Ref: Carcaillet C. and Blarquez O. 2019. Glacial refugia in the south-western Alps? New Phytologist, 14. http://doi.wiley.com/10.1111/nph.15673 

Offres de Maitrise: Potentiel de migration des érablières tempérées nordiques vers la forêt boréale 

Potentiel de migration des érablières tempérées nordiques vers la forêt boréale 

Proposition de 2 maîtrises ou 1 doctorat. Le doctorat engloberait les deux maîtrises.

Dans le cadre d’un projet conjoint entre le Ministère des forêts, de la faune et des parcs (MFFP) et plusieurs universités, nous sommes à la recherche d’étudiants à la maitrise dans le but de réaliser des études paléoécologiques. Ces études se situent dans le cadre d’un plus vaste projet visant l’analyse du potentiel de migration des érablières nordiques vers la forêt boréale, et plus précisément vers le domaine de la sapinière à bouleau blanc (Figure 1). La finalité du projet est l’acquisition de connaissances multidisciplinaires dans le but d’influencer les stratégies d’aménagement forestier des érablières nordiques dans un contexte de changements climatiques. Plus spécifiquement, nous nous intéresserons aux érables (Acer saccharumet A. rubrum), au bouleau jaune (Betula alleghaniensis), au pin blanc (Pinus strobus) et au thuya (Thuja occidentalis). Ces espèces devraient voir leur aire de répartition s’étendre vers le nord suite à l’augmentation future des températures. Par contre, cette expansion risque d’être contrainte par une matrice paysagère dans laquelle les conifères abondent ainsi que par une possible augmentation de la fréquence-sévérité des incendies.

Figure 1.  Localisation des érablières nordiques dans le domaine de la sapinière à bouleau jaune (SBj, points jaunes) et des érablières rouges dans le domaine de la sapinière à bouleau blanc (SBb, petits points rouges). Les deux gros points rouges sont les secteurs d’échantillonnage.


Le présent projet vise à caractériser l’évolution passée des érablières nordiques (domaine de la sapinière à bouleau jaune) ainsi que des peuplements mixtes dans lesquels l’érable rouge est présent. Ces derniers sont relativement bien représentés dans la portion sud du domaine de la sapinière à bouleau blanc. Notre hypothèse est que les sites accueillant aujourd’hui l’érable rouge étaient jadis occupés par d’autres espèces thermophiles (pin blanc…). Si c’est le cas, le potentiel de migration est rehaussé car il s’agirait alors pour les espèces tempérées de recoloniser des sites où elles étaient déjà présentes. Afin de valider cette hypothèse, il est nécessaire de procéder à des analyses paléoécologiques nous permettant de remonter dans le temps. Ces dernières porteront sur des indicateurs de l’évolution millénaire des paysages. Il s’agit du pollen, des macro-restes (ex. aiguilles de pin blanc) et des charbons de bois.

Maîtrise 1. Une première maîtrise sera consacrée à l’étude de deux archives sédimentaires. La première est une carotte sédimentaire lacustre prise au fond d’un lac jouxtant une érablière nordique. La seconde est un sédiment organique prélevé dans une petite tourbière sise dans l’érablière nordique. Les analyses polliniques se limiteront au sédiment lacustre. Les charbons de bois seront analysés dans les deux archives mais ceux contenus dans les sols organiques, de taille supérieure à ceux des sédiments lacustres, seront identifiés au genre et, si possible, à l’espèce. Plusieurs charbons d’espèces tempérées seront datés. Les macro-restes seront étudiés dans les deux archives. Nous accorderons cependant une attention particulière aux débris ligneux contenus dans le sédiment organique et de taille suffisante pour permettre leur identification. La végétation contemporaine entourant la tourbière sera également étudiée (âge des arbres, structure forestière…). La comparaison de ces deux archives nous permettra de reconstituer l’histoire plurimillénaire des paysages à une échelle régionale (le lac) et locale (tourbière) (Figure 2).

Maîtrise 2. Elle est similaire à la première maîtrise, mais elle est réalisée dans les érablières rouges de la portion sud du domaine de la sapinière à bouleau blanc.

Chacune de ces deux maîtrises ou le doctorat qui les regroupe permettra aux étudiants d’acquérir de solides connaissances dans les domaines de la paléoécologie (identification de pollen, de charbons de bois et de débris ligneux) et de la dynamique forestière. Ces deux volets seront accompagnés d’analyses statistiques relatives au domaine de l’écologie numérique. Le point d’attache des étudiants sera le laboratoire de paléoécologie de l’Université de Montréal (UdeM) http://paleoecologie.umontreal.ca. Par ailleurs, les étudiants feront partie d’une équipe plus large formée par l’ensemble des participants au projet des érablières nordiques. Ils auront aussi la chance de participer à des colloques nationaux et internationaux. Le financement annuel sera de l’ordre de 15 k. La direction des études sera assurée par les professeurs Olivier Blarquez (UdeM) et Yves Bergeron (UQAT) en collaboration avec Martin Lavoie (U. Laval), Martin Simard (U. Laval) et Pierre Grondin (MFFP). La maîtrise s’étendra sur une période de 2 ans, soit de mai 2019 à mai 2021. Si le projet se fait par le biais d’un doctorat, ce dernier portera sur une durée maximale de 4 ans.

Afin de postuler, envoyez une lettre de motivation, votre CV ainsi q’un relevé de notes récent à Olivier Blarquez: blarquez at gmail.com. L’étude des candidatures commence immédiatement et se poursuivra jusqu’à ce que les postes soient comblés. 

Figure 2.  Illustration du site d’échantillonnage des érablières nordiques. A. le sédiment lacustre, B. Le sédiment organique d’une petite tourbière à l’intérieur de l’érablière. Les deux archives seront analysées et comparées dans le but de connaître l’évolution plurimillénaire des paysages. Un site similaire sera étudié mais dans lequel le sommet des collines est occupé par l’érable rouge.

New paper: Taking Fire Science and Practice to the Next Level: Report from the PAGES Global Paleofire Working Group Workshop 2017 in Montreal, Canada – Paleofire Knowledge for Current and Future Ecosystem Management

I am glad to share the last paper from the GPWG Workshop in Montreal by Katarzyna et al. on the dialogue between stakeholders and paleofire researchers:
Marcisz K., Vannière B., Blarquez O. & the GPWG2. 2018. Taking Fire Science and Practice to the Next Level: Report from the PAGES Global Paleofire Working Group Workshop 2017 in Montreal, Canada – Paleofire Knowledge for Current and Future Ecosystem Management. Open Quaternary, 4(1), 7. http://doi.org/10.5334/oq.44
This report summarizes the outcome of the PAGES Global Paleofire Working Group workshop 2017 that took place in Montreal, Canada – Paleofire knowledge for current and future ecosystem management. The workshop aimed to (1) discuss the importance of past fire or paleofire research, focused on long-term influence of fire on the environments worldwide, in nature conservation, (2) find ways to integrate scientific achievements of paleofire research into ecosystem management practices, and (3) start the dialogue with ecosystem managers, practitioners and policymakers (EMPPs). With this report, the members of the Global Paleofire Working Group would like to open a discussion about how igniting new collaborations with EMPPs and make paleofire data useful for fire risk management. We recognized four main challenges in communication and cooperation between scientists and EMPPs: little awareness of EMPPs about paleofire research, differences in professional language used in an operational context by scientists and EMPPs, scientific data availability, and costs of paleoecological expertise. Moreover, we indicate the way to improve the communication between scientists and EMPPs by proposing a scheme of cooperation between both groups. We want to encourage researchers working in various fields of paleoecology to open up for the cooperation with EMPPs in the future, especially helping to create ecosystem management plans, because paleoecological data carry important information about the evolution of ecosystems that is vital in the context of global change.

New Paper: Using paleoecology to improve reference conditions for ecosystem-based management in western spruce-moss subdomain of Québec

I am very pleased to shared the first paper of Andy Hennebelle PhD dealing with management and paleoecology in the spruce forest of Québec: 

Hennebelle A., Grondin P., Aleman J. C., Ali A. A., Bergeron Y., Borcard D., & Blarquez O. 2018. Using paleoecology to improve reference conditions for ecosystem-based management in western spruce-moss subdomain of Québec. Forest Ecology and Management, 430, 157–165. https://doi.org/10.1016/j.foreco.2018.08.007 


Ecosystem based management in Québec is framed by reference conditions defining percentage of old-growth forest (> 100-years-old) and forest composition characterizing pre-industrial forest landscapes. In the western spruce-moss bioclimatic subdomain (154 184 km2) a fire cycle estimated at 150 years was used to target that 49% of the landscape has to be composed of old-growth forest. Yet, this target was developed using past (19th–20th C.) climate and vegetation data and assume that environment and ecosystem processes are homo- geneous for the entire western spruce-moss bioclimatic subdomain. The wide spatial and narrow temporal windows limit the application of reference conditions under ongoing climate change.

Our aim was to classify current vegetation heterogeneity of the western spruce-moss subdomain into homogeneous zones and to study the long-term history of fire and vegetation within these zones. This approach will help to refine forest management targets that are based upon short-term records by providing a long-term perspective that is needed for the forests to be managed within their natural range of variability. Modern forest inventories data were used along with climate, physical variables, and natural and human disturbances to study the current vegetation-environment interactions among the western spruce-moss subdomain. We also used 18 published sedimentary pollen and charcoal series to reconstruct Holocene vegetation and Fire Return Intervals (FRI).

Contemporary data revealed 4 zones with homogeneous interactions between vegetation and environment. Pollen analysis revealed three long-term vegetation paths: early successional species dominance, late to early species transition and late successional species dominance. These suggest that modern forest composition results from Holocene trajectories occurring within each zone. Holocene mean FRI (mFRI) ranged from 222 to 258 years across the subdomain, resulting in old-growth forests ranging between 64% and 68%, depending upon the zone.

Paleoecological and contemporary results support that to make forest management more sustainable, current landscape heterogeneity that arises from millennial forest composition trajectories and fire cycle dynamics should be taken into account by down-scaling the previously established reference conditions.