History of fire regime shifts during the last 1000 years in Northeastern Mongolia

Abstract

Recent years have seen rapid climatic changes in Central Asia, particularly Mongolia. An increase in the thickness of the active layer above permafrost and considerable changes to the vegetation structure are likely outcomes of the long-term temperature rise and precipitation changes. The management of future habitats or the biodiversity of northern Mongolia faces significant difficulties from rising temperatures, prolonged and frequent droughts, and gradual permafrost degradation. Our knowledge of the historical processes involved in permafrost degradation and the ensuing ecological effects is still mostly incomplete. These connections may be used to explain changes in the fire regime, permafrost melting, and plant distribution in the Khentii mountains region. Therefore, based on a multiproxy study of peat archive data, we provide the first high-resolution fire history from northeastern Mongolia over the last 1000 years (micro- and macroscopic charcoals, charcoal size classes and morphotypes, peat geochemistry). We examined microscopic and macroscopic charcoal particles as a proxy for fire activity. We also tracked changes in regional and local plant composition using pollen data. To investigate how changes in fire regimes and the climate affect the functioning of the peatland ecosystem, we also conducted a geochemical analysis.Additionally, to better comprehend the changes in earlier fire regimes and fire-vegetation connections, we employed the morphotypes of macrocharcoal to pinpoint vegetation burning. This study's primary objective is to evaluate the impact of human behavior, vegetation, and prolonged droughts on the incidence of fire regime transitions during the past 1000 years in Central Asia permafrost marginal zone (Mongolia). The findings showed that most of the fires in the area were probably started by natural causes, presumably connected to heatwaves that resulted in prolonged droughts. We have established a connection between increased fires and the local weather phenomena known as "dzud", a catastrophic confluence of winter snowfall and droughts that impacts fire intensity.The study is the result of research project No. 2017/01/X/ST10/01216 and 2018/31/B/ST10/02498 funded by the Polish National Science Centre.