Holocene stand-scale vegetation dynamics and fire history of an old-growth spruce forest in southern Finland

Abstract

Forest vegetation composition, including\ud dominant keystone species and floristic diversity, is driven\ud by natural and anthropogenic disturbances. Disentangling\ud these complex interactions to identify the role of species\ud competition, climate and disturbances in boreal forest dynamics\ud is challenging. Here, pollen and charcoal data are\ud used to reconstruct Holocene vegetation and fire history at\ud the local stand-scale within an old-growth Picea abies\ud (Norway spruce) forest hollow in southern Finland. The\ud aim is to reconstruct vegetation history with specific emphasis\ud on the mid-Holocene expansion of Picea and the\ud decline in deciduous species in relation to fire history.\ud Early-Holocene forest development and vegetation dynamics\ud are primarily driven by climatic variations. The\ud spread of Picea at approximately 5,200 cal BP does not\ud coincide with local natural or anthropogenic disturbance or\ud a decline in deciduous species and is consistent with its\ud regional expansion, suggesting climate as the most likely\ud control over the late establishment of this taxon. The mid-\ud Holocene decline in deciduous species corresponds to an\ud increased fire frequency suggesting a higher anthropogenic\ud disturbance (also considered as the primary reason for the\ud loss of floristic diversity in southern Finland). The ‘natural’\ud fire frequency in this local stand-scale boreal forest is lower\ud than that observed in the recent past (i.e. the time of significant\ud anthropogenic impact), yet the present-day absence\ud or low frequency of fire remains within the range of natural\ud variability observed during the early- and mid-Holocen

Forest history, peatland development and mid- to late Holocene environmental change in the southern taiga forest of central European Russia

“…6), most likely due to fire, with Betula and Pinus partly replacing other species in secondary forest (Gromtsev, 2002). The same features were observed in a number of pollen diagrams from boreal forests in Finland (Clear et al, 2015), Russian Karelia (Kuosmanen et al, 2016), and central European Russia (Novenko et al, 2016), where pollen values of pioneer trees ( Pinus, Betula, Alnus , and Populus ) increased significantly following charcoal peaks. It is important to note, however, that the abundance of wind-pollinated plants with high pollen productivity, such as Betula, Alnus , and Pinus , is always overestimated (Lisitsyna et al, 2011; Marquer et al, 2014; Novenko et al, 2017).…”

“…6) most likely due to fire, with Betula and Pinus partly replacing other species in secondary forest (Gromtsev, 2002). The same features were observed in a number of pollen diagrams from boreal forests in Finland (Clear et al, 2015), Russian Karelia (Kuosmanen et al, 2016), and central European Russia (Novenko et al, 2016),…”

“…In the European boreal zone, the available paleoecological data indicate that coniferous forests expanded between 5700 and 2500 cal yr BP (Kremenetski et al, 2000; Kalis et al, 2003; Seppä and Poska, 2004; Giesecke and Bennett, 2004; Giesecke, 2005; Zernitskaya and Mikhailov, 2009; Novenko et al, 2009b; Marquer et al, 2014). Conifers replaced broadleaved deciduous species, which had been abundant during the Holocene thermal maximum (8000–5500 cal yr BP), apparently due to climatic cooling and increased land surface wetness (e.g., Seppä and Birks, 2001; Novenko et al, 2009b; Olchev and Novenko, 2011), in combination with increasing anthropogenic disturbance (Clear et al, 2015; Novenko et al, 2015). During recent decades, a large number of studies have explored the paleoecology of eastern Europe and European Russia, including studies focused on vegetation history, wetland development, and carbon accumulation by peatlands (Arslanov et al, 1999; Stančikaite et al, 2006; Niinemets and Saarse, 2009; Heikkilä and Seppä, 2010; Mauquoy et al, 2002; Mauquoy and Yeloff, 2008; Mitsch et al, 2013; Tuittila et al, 2014; van der Linden et al, 2014).…”

Importance of climate, forest fires and human population size in the Holocene boreal forest composition change in northern Europe

“…The high explanatory value of climate explaining the variation in pollen data from lakes shows that these sites are suitable for such reconstructions, whereas the low explanatory values of climate explaining the variation in pollen data in small hollow records suggest that pollen records from small hollows or small lakes are not suitable for reconstructing past climate, as was also observed by Clear et al . (). The same is true in the pollen‐climate calibration models on which the pollen‐based climate reconstructions are based.…”

Integrating fire-scar, charcoal and fungal spore data to study fire events in the boreal forest of northern Europe

“…. We compared our findings to nearby sites studied earlier: 4 -Sudenpesä (Clear et al, 2015); 5 -Vesijako (Clear et al, 2013); 6 -Kukka hollow, 7 -Larix hollow, 8 -Mosquito hollow and 9 -Olga hollow (Kuosmanen et al, 2014). Figure 2.…”