Jade Margerum, Julia Homann, Stuart Umbo, Gernot Nehrke, Thorsten Hoffmann, Anton Vaks, Aleksandr Kononov, Alexander Osintsev, Alena Giesche, Andrew Mason, Franziska A. Lechleitner, Gideon M. Henderson, Ola Kwiecien, Sebastian F. M. Breitenbach
{"title":"Reconstruction of Holocene and Last Interglacial vegetation dynamics and wildfire activity in southern Siberia","authors":"Jade Margerum, Julia Homann, Stuart Umbo, Gernot Nehrke, Thorsten Hoffmann, Anton Vaks, Aleksandr Kononov, Alexander Osintsev, Alena Giesche, Andrew Mason, Franziska A. Lechleitner, Gideon M. Henderson, Ola Kwiecien, Sebastian F. M. Breitenbach","doi":"10.5194/egusphere-2024-1707","DOIUrl":null,"url":null,"abstract":"<strong>Abstract.</strong> Wildfires are a rapidly increasing threat to boreal forests. While our understanding of the drivers behind wildfires and their environmental impact is growing, it is mostly limited to the observational period. Here we focus on the boreal forests of southern Siberia, and exploit a U-Th dated stalagmite from Botovskaya cave (55.2994° N, 105.4445° E), located in the upper Lena region of southern Siberia, to document wildfire activity and vegetation dynamics during parts of two warm periods; the last interglacial (124.1 – 118.8 ka BP) and the Holocene (10 – 0 ka BP). Our record is based on levoglucosan (Lev), a biomarker sensitive to biomass burning, and on lignin oxidation products (LOPs) that discriminate between open and closed forest and hard- or softwood vegetation. In addition, we used carbon stable isotope ratios (δ<sup>13</sup>C) to evaluate soil respiration and local infiltration changes. While the δ<sup>13</sup>C record reflects a dominant control of the host rock, the Lev and LOP time series show fire pattern and vegetation type differences between the last interglacial and the Holocene. Our LOP data suggest that during the last interglacial, the region around Botovskaya cave was characterised by open forest, which by ca. 121.5 ka BP underwent a transition from fire-resistant hardwood to fire-prone softwood. The Lev record indicates that fire activity was high and increased towards the end of last interglacial just before 119 ka BP. In contrast, the Holocene was characterised by a closed-forest environment with mixed hard- and softwood vegetation. Holocene fire activity varied but at a much lower level than during the last interglacial. We attribute the changes in wildfire activity during the intervals of interest to the interplay between vegetation and climate. The open forests of the last interglacial were more likely to ignite than their closed Holocene equivalents, and their flammability was aided by warmer and drier summers and a stronger seasonal temperature contrast compared to the Holocene. Our comparison of the last two interglacial intervals suggests that with increasing global temperatures the boreal forest of southern Siberia becomes progressively more vulnerable to higher wildfire activity.","PeriodicalId":10332,"journal":{"name":"Climate of The Past","volume":"51 1","pages":""},"PeriodicalIF":3.8000,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Climate of The Past","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5194/egusphere-2024-1707","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Abstract. Wildfires are a rapidly increasing threat to boreal forests. While our understanding of the drivers behind wildfires and their environmental impact is growing, it is mostly limited to the observational period. Here we focus on the boreal forests of southern Siberia, and exploit a U-Th dated stalagmite from Botovskaya cave (55.2994° N, 105.4445° E), located in the upper Lena region of southern Siberia, to document wildfire activity and vegetation dynamics during parts of two warm periods; the last interglacial (124.1 – 118.8 ka BP) and the Holocene (10 – 0 ka BP). Our record is based on levoglucosan (Lev), a biomarker sensitive to biomass burning, and on lignin oxidation products (LOPs) that discriminate between open and closed forest and hard- or softwood vegetation. In addition, we used carbon stable isotope ratios (δ13C) to evaluate soil respiration and local infiltration changes. While the δ13C record reflects a dominant control of the host rock, the Lev and LOP time series show fire pattern and vegetation type differences between the last interglacial and the Holocene. Our LOP data suggest that during the last interglacial, the region around Botovskaya cave was characterised by open forest, which by ca. 121.5 ka BP underwent a transition from fire-resistant hardwood to fire-prone softwood. The Lev record indicates that fire activity was high and increased towards the end of last interglacial just before 119 ka BP. In contrast, the Holocene was characterised by a closed-forest environment with mixed hard- and softwood vegetation. Holocene fire activity varied but at a much lower level than during the last interglacial. We attribute the changes in wildfire activity during the intervals of interest to the interplay between vegetation and climate. The open forests of the last interglacial were more likely to ignite than their closed Holocene equivalents, and their flammability was aided by warmer and drier summers and a stronger seasonal temperature contrast compared to the Holocene. Our comparison of the last two interglacial intervals suggests that with increasing global temperatures the boreal forest of southern Siberia becomes progressively more vulnerable to higher wildfire activity.
期刊介绍:
Climate of the Past (CP) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on the climate history of the Earth. CP covers all temporal scales of climate change and variability, from geological time through to multidecadal studies of the last century. Studies focusing mainly on present and future climate are not within scope.
The main subject areas are the following:
reconstructions of past climate based on instrumental and historical data as well as proxy data from marine and terrestrial (including ice) archives;
development and validation of new proxies, improvements of the precision and accuracy of proxy data;
theoretical and empirical studies of processes in and feedback mechanisms between all climate system components in relation to past climate change on all space scales and timescales;
simulation of past climate and model-based interpretation of palaeoclimate data for a better understanding of present and future climate variability and climate change.