Human-induced changes in fire regime and subsequent alteration of the sandstone landscape of Northern Bohemia (Czech Republic)

Abstract

Multiproxy palaeoecological evidence from a sandstone region in northern Czech Republic was collected to explore the impact of fire disturbances on the decline of the broadleaved forests during the Late Bronze Age (3250-3050 cal. BP). It has been hypothesized that human-accelerated soil leaching affected the nutrient availability in the sandstone area, thus promoting the expansion of oligotrophic-adapted plant communities in the late-Holocene.Little is known about the mechanisms which induced such large-scale vegetation transformation. We sought to determine which driving forces were involved using independent proxy records -soil and sedimentary charcoal, pollen and fungal spores. Local fire history was derived from the variation in charcoal accumulation rates (CHAR) preserved in Eustach peatbog. The fire frequency (FF) estimation over the past ~7500 years revealed distinct phases of increased burning between 3100 and 2120 cal. BP (3.0 fires 1000 yr −1 ) and 1400-600 cal. BP (4.3 fires 1000 yr −1 ). Rapid compositional changes in the pollen assemblage were documented during the Late Bronze Age period, suggesting vegetation responded to increased fire disturbances. The human influence on the fire regime is implied by the short-term increase in cereal pollen concurrent with a major fire event, indicating possible use of slash-andburn cultivation by Late Bronze societies. This type of human subsistence strategy practised in the sandstone landscape further evolved to pastoralism as suggested by continuous presence of coprophilous fungi Sporormiella and Sordaria, which occurred since the Hallstatt/La Tène period (2750-1950 cal. BP). Our study documents, for the first time, the intentional, human-caused biomass burning from densely forested areas of Northern Bohemian sandstone region. Our results imply that increased rate of fire disturbances contributed to the Late Bronze Age transformation of broadleaved forests to oligotrophic forest communities of late-Holocene.

Holocene-scale fire dynamics of central European temperate spruce-beech forests

“…, fire is considered a negligible disturbance agent in central European temperateforests. Yet, the results of this study support emerging literature demonstrating that fires have been an important disturbance agent throughout the Holocene in temperate forests (e.g Clark et al, 1989;Bobek et al 2017;Niklasson et al, 2010;Novák et al 2012)…”

“…Yet, over the past decade emerging literature has demonstrated that fires have occurred for millennia in central European forested ecosystems (e.g. Clark et al, 1989;Bobek et al 2017;Niklasson et al, 2010;Novák et al 2012). However, crucial parameters of fire regimes i.e.…”

Changing disturbance‐diversity relationships in temperate ecosystems over the past 12000 years

“…Fires represent the best recorded disturbance factors in palaeoecological data (Power et al, 2007;Vannière et al, 2016). Identification of significant peaks in charcoal records suggests fire frequency of 250-500 years (Bobek, Svobodová, Werchan, Švarcová, & Kuneš, 2018;Carter et al, 2018) during the middle Holocene in our study region although frequency seems to increase abruptly in recent centuries (Niklasson et al, 2010). However, it should be noted that any quantitative comparison with individual charcoal events lies beyond capabilities of our data, which encompass all disturbance factors showing an overall disturbance regime capturing various disturbance means (see Section 2; Herben et al, 2016).…”

The lost paradise of snails: Transformation of the middle-Holocene forest ecosystems in Bohemia, Czech Republic, as revealed by declining land snail diversity

“…(e.g. Bobek et al., 2018; Härtel et al., 2007; Novák et al., 2015; Šída et al., 2014a, 2014b; Svoboda, 2003, 2017; Svoboda et al., 2018). Thanks to these investigations, sandstone landscapes have revealed examples of the extreme and rapid impoverishment of local biota, which was originally attributed to the late Bronze Age colonization and accompanying human impacts and interpreted as environmental collapse (Härtel et al., 2007; Pokorný and Kuneš, 2005), sometimes expressively called the ‘Lusitanian Catastrophe’ (Cílek et al., 1996).…”

“…Thanks to these investigations, sandstone landscapes have revealed examples of the extreme and rapid impoverishment of local biota, which was originally attributed to the late Bronze Age colonization and accompanying human impacts and interpreted as environmental collapse (Härtel et al., 2007; Pokorný and Kuneš, 2005), sometimes expressively called the ‘Lusitanian Catastrophe’ (Cílek et al., 1996). Recently, anthropogenic forest fires were shown to be an important driver of these dynamics (Bobek et al., 2018).…”