Fires, vegetation, and human-The history of critical transitions during the last 1000 years in Northeastern Mongolia.

Fires are natural phenomena that impact human behaviors, vegetation, and landscape functions. However, the long-term history of fire, especially in the permafrost marginal zone of Central Asia (Mongolia), is poorly understood. This paper presents the results of radiocarbon and short-lived radionuclides (210Pb and 137Cs) dating, pollen, geochemical, charcoal, and statistical analyses (Kohonen's artificial neural network) of sediment core obtained from Northern Mongolia (the Khentii Mountains region). Therefore, we present the first high-resolution fire history from Northern Mongolia covering the last 1000 years, based on a multiproxy analysis of peat archive data. The results revealed that most of the fires in the region were likely initiated by natural factors, which were probably related to heatwaves causing prolonged droughts. We have demonstrated the link between enhanced fires and "dzud", a local climatic phenomenon. The number of livestock, which has been increasing for several decades, and the observed climatic changes are superimposed to cause "dzud", a deadly combination of droughts and snowy winter, which affects fire intensity. We observed that the study area has a sensitive ecosystem that reacts quickly to climate change. In terms of changes in the vegetation, the reconstruction reflected climate variations during the last millennium, the degradation of permafrost and occurrence of fires. However, more sites with good chronologies are needed to thoroughly understand the spatial relationships between changing climate, permafrost degradation, and vegetation change, which ultimately affect the nomadic societies in the region of Central and Northern Mongolia.

Water table depth, experimental warming, and reduced precipitation impact on litter decomposition in a temperate Sphagnum-peatland.

The Tea Bag Index (TBI) method was used to estimate the litter decomposition rate in peatland exposed for climate manipulation (increased temperature and reduced precipitation) at two contrasting sites differing in water table depth (WTD) dynamics. To manipulate climate on peatland, the prototyped Open Top Chambers (OTC) and automated rain-out shelters were used. OTCs increased daytime air temperatures by ~1.7 °C at the driest plots exposed for an increase of air temperature and reduced precipitation, while the increase of the average daily air temperature was lower than 0.9 °C. However, OTCs cooled down the peat temperature even by 0.8 °C and this effect was most pronounced for daytime rather than night-time conditions. The precipitation amount was reduced by 26%. The tea bags were buried at 8 cm depth for 83 and 172 days starting from the 19th of April 2019. Our observation proved that although decomposition rates were dependent on temperature, WTD and its fluctuations are the main factors controlling the rates of litter decomposition in waterlogged ecosystems like ours. At waterlogged Sphagnum-dominated peatlands, the interrelation between different environmental factors may mitigate the impact of warming and reduced precipitation on litter decomposition.

Paleoecological and historical data as an important tool in ecosystem management.

In recent decades, it has been observed that most forest fires in Europe were caused by people. Extreme droughts, which are more often prolonged, can increase the risk of forest fires, not only in southern Europe but also, in Central Europe. Nonetheless, catastrophic fire events are not well recognized in the Central European Lowlands (CEL), where large forest complexes are located. Knowledge of past fire activity in this part of Europe is scarce, although several fires have occurred in this area during the previous millennia. Large coniferous forest monocultures located in the CEL are highly susceptible to fires and other disturbances. Here, we present a case study from the Tuchola Pinewoods (TP; northern Poland), where large pine monocultures are present. The main aim of this study is to document the potential effects past land management has on modern day disturbance regimes using state-of-the-art paleoecological data, historical documents and cartographic materials. We then present a protocol that will help forest managers utilize long-term paleoecological records. Based on paleoecological investigations, historical documents, and cartographic materials, our results show that, in the past 300 years, the TP witnessed not only disastrous fires and but also windfalls by tornados and insect outbreaks. A change in management from Polish to Prussian/German in the 18th century led to the transformation of mixed forests into Scots pine monocultures with the purpose to allow better economic use of the forest. Those administrative decisions led to an ecosystem highly susceptible to disturbances. This article provides a critical review of past forest management as well as future research directions related to the impacts of fire risk on land management and ecosystem services: (a) habitat composition and structure (biodiversity); (b) natural water management; and (c) mitigation of climate changes. Designated forest conditions, management, and future fire risk are a controversial and highly debated topic of forest management by Forestry Units. More research will allow the gathering of reliable information pertinent to management practices with regard to the current fire risks. It is necessary to develop a dialog between scientists and managers to reduce the risk of fires in projected climate change.