Enhanced hydrological disturbance and atmospheric pollution on an ombrotrophic peatland (Greater Khingan Mountains, Northeast China) since 1950s inferred from diatom records

Anthropogenic source emissions have caused unprecedented atmospheric environment pollution and natural ecosystem destruction in recent decades. It is necessary to explore the relationships among human, environment and ecosystem in a global change context. Ombrotrophic peatlands are precipitation-dependent and derive nutrients solely from atmospheric deposition, which can document environmental changes continuously. Diatoms preserved in peat sediments are abundant and diverse, and sensitive to hydrological environment changes. Here we reconstructed the historical water table conditions based on diatom from an ombrotrophic peatland in the northern Greater Khingan Mountains, and to assess the influence of climate and human on ecosystem development over the past 150 years. Our results revealed the hydrological condition in Hongtu (HT) peatland was mainly impacted by climate before 1950 AD. HT peatland remained in a pristine state with minimal human interference, as native inhabitants continued to hunt and gather. After the New China was established in 1949 AD, high frequency of fire events caused by rapid population growth, mining and industry destroyed the diatom diversity. Higher water table in HT peatland from 1950 AD to 1965 AD was resulted by higher rainfall. Since 1980 AD, especially after 2000 AD, a suddenly increase of tolerant diatoms species (Achnanthidium minutissimum and Craticula molestiformis) indicated enhanced anthropogenic disturbance. Anthropogenic emissions caused by industrial production and coal consumption increased the atmospheric nitrogen deposition. The abnormal drought of HT peatland was influenced by both climate warming and human activities since 1980s. The recent and strong effects of human activities on peatlands left significantly stratigraphic signals of the Anthropocene in peat deposits. Diatoms have potential to be applied as indicators of long-term hydrological changes in ombrotrophic peatlands, as they are highly sensitive to environmental changes and human disturbance.