The role of tree composition in Holocene fire history of the hemiboreal and southern boreal zones of southern Sweden, as revealed by the application of the Landscape Reconstruction Algorithm: Implications for biodiversity and climate-change issues

Abstract

We present a quantitative reconstruction of local forest history at two sites, Stavsåkra (hemiboreal zone) and Storasjö (southern boreal zone), in southern Sweden (province of Småland) to evaluate possible causes of contrasting Holocene fire histories in mid-and late Holocene. The Landscape Reconstruction Algorithm (LRA) is applied to evaluate between-site differences in the relative abundance of deciduous trees and Pinus (pine) and landscape/woodland openness during the Holocene. The LRA estimates of local vegetation abundance are compared with other proxies of local vegetation, that is, plant and beetle remains. The LRA results suggest that Pinus was a major tree taxon in the woodlands of Storasjö during mid-and late Holocene, while Tilia (linden) and Betula (birch) were dominant at Stavsåkra. The contrasting fire histories are shown to be strongly related to between-site differences in tree composition during mid-Holocene, 4000-2000 bc in particular. The archaeological/historical and beetle data indicate contrasting land uses from c. 1000 bc (late Bronze Age/early Iron Age), grazing in open Calluna heaths at Stavsåkra and woodland grazing at Storasjö. Between-site differences in fire history during late Holocene were likely due to different land-use practices. Between-site differences in tree composition in mid-Holocene are best explained by local climatic and geological/geomorphological differences between the hemiboreal and southern boreal zones of Småland, which might also be the primary cause of between-site differences in land-use histories during late Holocene. Maintenance of biodiversity at the landscape scale in the study area requires that existing old pine woodlands and Calluna heath are managed with fire and cattle grazing. Further climate warming might lead to higher probabilities of climate-induces fire, in particular in pine-dominated woodlands.

Are pollen records from small sites appropriate for REVEALS model-based quantitative reconstructions of past regional vegetation? An empirical test in southern Sweden

“…Kansjön REVEALS estimates. Cui et al (2013) assumed that the mean REVEALS estimates from Kansjön and Trummen was a good approximation of the regional vegetation influencing the pollen assemblages at three small study sites located in the hemiboreal zone (two sites) and the southern boreal zone (one site). This assumption is now supported by the results of this study.…”

“…In bold: large lakes Veget Hist Archaeobot (2016) 25:131-151 133 of past vegetation composition have already been shown to be useful for (i) the quantitative reconstruction of vegetation/plant cover at the local spatial scale (10-100 km 2 ) using Sugita's LRA (e.g. Nielsen and Odgaard 2010;Cui et al 2013Cui et al , 2014Mazier et al 2015;Hultberg et al 2015), (ii) the study of regional spatio-temporal land-cover/landscape dynamics over the past millennia (e.g. Marquer et al 2014;Fyfe et al 2013;Nielsen et al 2012;Trondman 2014), (iii) the evaluation of anthropogenic land-cover change scenarios (ALCCs) (Gaillard et al 2010) and (iv) the study of land cover-climate interactions in the past (Strandberg et al 2014).…”

A case study of the role of climate, humans, and ecological setting in Holocene fire history of northwestern Europe

“…In this paper, we present the major results from new (Cui, 2013) and previous (Greisman and Gaillard, 2009;) studies of fire history over the last 11000 years (Holocene) in southern Sweden based on palaeoecological analyses of peat sequences from three small peat bogs. The main objective of the paper is to emphasize (1) the value of multiple, continuous sedimentary records of macroscopic charcoal for the reconstruction of local to regional past changes in fire regimes, (2) the importance of multi-proxy records (here pollen, plant macrofossils, beetles and charcoal) to cross-check interpretation of the proxies in terms of fire and human-impact history, and (3) the advantage of model-based estimates of plant cover from pollen data to assess the role of tree composition and human impact in fire history.…”

From deciduous forest to open landscape: application of new approaches to help understand cultural landscape development in western Norway

“…The LOVE reconstruction shows that the cultural landscape has been more open than is suggested by pollen percentages alone, which is a general pattern seen when using LRA (Hellman et al 2008;Nielsen et al 2012;Cui et al 2013;Fyfe et al 2013;Hultberg et al 2015). There are still challenges in the use of LRA, including the fact that not all of the most commonly registered pollen taxa have PPEs.…”

“…The Landscape Reconstruction Algorithm (LRA) is an approach developed to deal with the challenges-differences in pollen production and dispersal between species-and convert pollen percentages into vegetation cover (Sugita 2007a, b). So far, estimates achieved from this approach are found to be representative of the vegetation in Denmark, Switzerland, Sweden, Estonia and Norway (Hellman et al 2008;Nielsen and Odgaard 2010;Soepboer et al 2010;Fredh 2012;Cui et al 2013;Overballe-Petersen et al 2013;Poska et al 2014;Hjelle et al 2015), and it has been applied to reconstruct vegetation cover on different spatial scales (e.g. Nielsen et al 2012;Fyfe et al 2013;Cui et al 2014;Marquer et al 2014;Hultberg et al 2015;Trondman et al 2015).…”