Here, from macrophylogeographic mtDNA empirical data, we propose a scenario for the evolution and speciation of two important forest trees, European black pine and Scotch pine, and their multiple subspecies and varieties. Molecular clock simulations revealed that INDEL variability in the Pinus mitochondrial genome is relatively old, i.e., from the Pliocene-Miocene epoch, and related to historical tectonic continental fluctuati...

We used bioproxies from paleosoils buried within two aeolian dunes to test hypotheses concerning the origin of dry sandy boreal forests in Canada. These forests are dominated today by Pinus banksiana Lamb. One hypothesis is that too frequent Holocene stand-replacing fires would have transformed the original vegetation through extirpation of susceptible species to fire in water stress habitat. Alternatively, the ecosystem would...

The influence of different drivers on changes in North American and European boreal forests biomass burning (BB) during the Holocene was investigated based on the following hypotheses: land use was important only in the southernmost regions, while elsewhere climate was the main driver modulated by changes in fuel type. BB was reconstructed by means of 88 sedimentary charcoal records divided into six different site clusters. A...

Aim Potential fire intensity ( PFI ) is among the main drivers of fire–vegetation interactions, but how it varies across species ranges is unknown. We test whether PFI and crown fire likelihood ( CFL ) increase preferentially towards the warm/dry range margins of mountain trees. Location The western Alps. Methods We analysed PFI and CFL patterns across the environmental niches of major mountain forest tree species, using field...

Up to now, the most widely accepted idea of the periglacial environment is that of treeless ecosystems such as the arctic or the alpine tundra, also called the tabula rasa paradigm. However, several palaeoecological studies have recently challenged this idea, that is, treeless environments in periglacial areas where all organisms would have been exterminated near the glacier formed during the Last Glacial Maximum, notably in t...

Aim Little is known about the understorey flammability of European mountain forests. The aim of this study was to determine the relative effects of climate, vegetation structure and composition on the fuel‐driven variation in fire spread and intensity. Location The western Alps. Methods Fire spread and intensity were simulated under constant moisture and weather conditions for a wide range of understorey fuel parameters measur...

Aim Towards the cold margins of the Northern Hemisphere boreal zone, continuing warming should theoretically provide a longer vegetative season, favouring growth and a northward shift in tree species distribution. The northern distribution of Thuja occidentalis L. (eastern white cedar) is marked by the presence of isolated marginal populations distant from the continuous distribution. If those populations proved to be well ada...

We analysed charcoal and pollen from sediments obtained from two lakes in the northwestern mixed‐wood Canadian boreal forest in order to reconstruct fire‐return intervals and vegetation dynamics over the last 8000 years. Sites were selected with contrasting soil properties (mesic versus dry‐sandy soils), allowing an estimation of the potential influence of soils on long‐term vegetation and fire dynamics. The sites likely exper...

We investigated changes in wildfire risk over the 1901−2002 ( ad ) period with an analysis of broad‐scale patterns of July monthly drought code (MDC) variability on 28 forested ecoregions of the North American and Eurasian continents. The MDC is an estimate of the net effect of changes in evapotranspiration and precipitation on cumulative moisture depletion in soils, and is well correlated with annual fire statistics across th...

The influence of climatic and local nonclimatic factors on the fire regime of the eastern Canadian boreal forest over the last 8000 years is investigated by examining charred particles preserved in four lacustrine deposits. Herein, we compare the distribution of fire‐free intervals (FFIs) and the synchronicity of fire events among sites, using Ripley's K ‐function to determine the extent of the role of local‐scale vs. large‐sc...