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Mountain ecosystems are sensitive to environmental changes and are affected by direct and indirect anthropogenic activities. This study sought to understand the impacts of human occupation, environmental and climate change on the Great Hinggan Mountains (GHM) in Northeastern China. The last 200 years of environmental changes are reconstructed by analyzing sediment cores from five small mountain lakes. Cores were dated using 210Pb and 137Cs radioisotopes, microscopic charcoal identified regional fire activity and fossil pollen analysis reconstructed temporal and spatial changes in vegetation. Peaks in 137Cs, 226Ra and microscopic charcoal flux were found to follow similar trends between sites. The radioisotope records reflect redistribution processes, such as erosion and fire events, which overwhelm the atmospheric fallout signal in the GHM. Microscopic charcoal increased from 1950 CE and peaked at all sites after 2000 CE suggesting that current fire management, coupled with a warmer climate due to global warming, may be leading to more wildfire events in the region. Pinus, Quercus and Betula declined at all sites as human occupation occurred in the early 1900s. Initially, open forest and grassland expanded in response to overexploitation of forests, followed by arboreal pollen reaching maximum values after 2000 CE. This study concludes that the present‐day mixed coniferous broad‐leaved forest dominating the southern region of the GHM is a product of changing fire activity, excessive logging and, more recently, forestry management and vegetation regeneration. Results suggest further management strategies are needed to address land degradation and wildfire events in mountain regions of Northeastern China. [ABSTRACT FROM AUTHOR]

A multi-proxy record of Holocene and late-Pleistocene aeolian mineral dust is reconstructed using a combination of geochemical (trace elements), mineralogical and grain-size analyses on cores from the Hani peatland in north-eastern (NE) China. The dust record displays a sharp increase in dust deposition during the late Holocene in comparison to the rest of the Holocene. This trend is in line with climatic records from the Chinese dust source regions and their downwind areas, which generally show an increase in aridity and aeolian activity during the late Holocene. The larger part of the Chinese dust source regions experienced a gradual increase in effective moisture and vegetation cover reaching maxima during the middle Holocene (6.0–8.0 kyr cal. BP) co-occurring with the minima in dust deposition in Hani. These changes in the dust source regions are likely to have been modulated by the variations in the East Asian summer monsoon (EASM), which is the principal mechanism controlling climate in the region. The intensified EASM during the middle Holocene is also likely to have resulted in a sediment recharge at the margin of the Chinese drylands providing additional material and enhancing the atmospheric dust load after the late-Holocene aridification of the region. Combined together, these changes promoted a remobilization of dust sources increasing the amount of material available for transport by the East Asian winter monsoon (EAWM) and the Westerlies. Human activities might also have played a role in the increased dust emissions during the late Holocene, but further research is needed to assess the extent of those impacts at a regional level. [ABSTRACT FROM AUTHOR]