• We report sedimentary charcoal composites for the Central European lowlands (CEL). • Holocene fire activity shows convergence and divergence across three spatial scales. • Divergence in low-flammability periods reflects cultural fire use in land management. • Since 8,500 cal. BP, humans affected CEL-biogeochemical cycles beyond the local scale.
The development of vegetation in the Skaliska Basin has been reconstructed on the basis of palynological analysis and radiocarbon dating (AMS technique) of 6 sites from the late phase of the Bolling- Allerod interstadial complex to modern times. Although the area covers 90 km2, the mosaic character of habitats led to the development of different patterns of vegetation changes during the Late Glacial and Holocene. Only one site located in the eastern part of the Skaliska Basin reflected the ‘pine phase’ of Allerod, and this is the oldest data on vegetation in the Skaliska Basin. Interesting discrepancies were recorded during the Younger Dryas when patches of shrublands with Juniperus were distinct around some of the sites, while steppe with Artemisia was common in others. The beginning of the Holocene brought an expansion of birch-pine forest, but around 9600 cal. BC a cold oscillation took place which was reflected in an increase in birch in the woodlands in the western and eastern part of the Skaliska Basin. In the Preboreal chronozone elm (Ulmus) also expanded in the area but its appearance was non-synchronous. The vegetation of the Boreal chronozone was similar in the whole area and the most characteristic feature was the rapid expansion of hazel (Corylus avellana) which displaced Betula from the most of its sites. At that time a distinct redeposition of pollen material in the Parchatka river valley was detected which was probably the effect of an increase in fluvial activity of the river (humid oscillation). The following stage of vegetation development was climax woodlands with Tilia cordata, Ulmus, Quercus, Corylus avellana, and Alnus in damp places. At the beginning of the Subboreal chronozone the expansion of Quercus took place, which was subsequently replaced by Picea abies and partly Carpinus betulus. The pattern of Picea abies expansion distinctly presents two maxima which is characteristic of many sites in the north-eastern Poland. The Subatlantic chronozone is represented only by the profile from the Skaliski Forest, where, because of sandy ground, Pinus sylvestris was the dominant element. Human impact was poorly reflected through the rare occurrence of pollen grains of Cerealia type in the pollen profiles spanning the time from the Subboreal chronozone to modern times. In most profiles AMS dating produced age discrepancies, which limited the possibility of establishment of a detailed chronology. However, dates obtained from the material contaminated by mixture of glycerine, thymol and ethyl alcohol, pretreated by alcohol, showed reliable results in most cases.
Abstract. Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding the risk of fires is quantifying the mediating effect of vegetation on fire regimes. Here, we explore the relative importance of Holocene land cover, land use, dominant functional forest type, and climate dynamics on biomass burning in temperate and boreo-nemoral regions of central and eastern Europe over the past 12 kyr. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and statistical modelling. Biomass burning was highest during the early Holocene and lowest during the mid-Holocene in all three ecoregions (Atlantic, continental and boreo-nemoral) but was more spatially variable over the past 3–4 kyr. Although climate explained a significant variance in biomass burning during the early Holocene, tree cover was consistently the highest predictor of past biomass burning over the past 8 kyr. In temperate forests, biomass burning was high at ∼45 % tree cover and decreased to a minimum at between 60 % and 70 % tree cover. In needleleaf-dominated forests, biomass burning was highest at ∼ 60 %–65 % tree cover and steeply declined at >65 % tree cover. Biomass burning also increased when arable lands and grasslands reached ∼ 15 %–20 %, although this relationship was variable depending on land use practice via ignition sources, fuel type and quantities. Higher tree cover reduced the amount of solar radiation reaching the forest floor and could provide moister, more wind-protected microclimates underneath canopies, thereby decreasing fuel flammability. Tree cover at which biomass burning increased appears to be driven by warmer and drier summer conditions during the early Holocene and by increasing human influence on land cover during the late Holocene. We suggest that long-term fire hazard may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene.
A high-resolution plant macrofossil record was examined alongside pollen, micro-and macrocharcoal, and testate amoeba data to elucidate the dynamics of two permafrost peatlands in the northern foothills of the Brooks Range, Alaskan Arctic. The vegetation dynamics of these two peatlands were driven by autogenic processes reflecting the development trajectory of the peatlands towards ombrotrophic status, and allogenic climate change. We observe an increase in shrub pollen and macrofossils (e.g. Ericaceae, Betula nana) during two Late Holocene warm episodes and in recent decades. Pollen data suggest that regional forest cover also responded to temperate increase since ca. AD 1950. An increase of Picea pollen (up to 13%) in the upper part of peat profile is probably associated with long distance pollen transport from populations of Picea mariana and Picea glauca located at the southern foothills of the Brooks Range. Relatively small amount of micro-and macrocharcoal in the two profiles indicates little fire activity around the sampling sites over the last ca. 2000 years, which is in agreement with regional findings. The lack of surface and groundwater influence under prolonged warmer/drier condition can allow Sphagnum to expand in Arctic peatlands. Cold climatic conditions might have been detrimental to Sphagnum populations, that were replaced by Carex spp. and other vascular plants owing to wetter conditions in the peatland.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.