Relations of fire, palaeohydrology, vegetation succession, and carbon accumulation, as reconstructed from a mountain bog in the Harz Mountains (Germany) during the last 6200 years

Mountain peatland ecosystems are unique islands of biodiversity, hosting endangered, vulnerable, and protected plants and animals. In addition, these ecosystems constitute important natural carbon stores. Their stratigraphy can be used to reconstruct the development of these ecosystems as well as the impact of various human activity over millennia. To examine the dynamics of an ombrotrophic peatland (Odersprungmoor) ecosystem in the Harz Mts. (Germany) in relation to environmental changes, fire, pollution and human activity, we have undertaken high-resolution analyses of plant macrofossils, testate amoebae, macrocharcoal morphologies, non-destructive X Ray fluorescence and carbon (delta C-13) and nitrogen (delta N-15) stable isotopes, and bulk density, combined with radiocarbon dating (AMS). Our study revealed that: i) the pristine plant populations composed mainly by Sphagnum fuscum and Sphagnum rubellum were replaced by Sphagnum medium/divinum since the Middle Age (ca. 600 cal yr BP) presumably due to pollution deposition. Hence we suggest that i) bogs in the Harz Mts. might have lost their natural character, and that oligotrophic Sphagnum species populations have either diminished or were replaced by vascular plant populations, ii) long-term carbon accumulation rates were similar to those from northern hemisphere lowland peatlands, and changing rates over time may be linked to changes in plant composition and water table depth, iii) fire episodes, which intensified during hydrological disturbances, partly impacted plant succession, iv) Eriophorum vaginatum is a good indicator of local hydrological disturbances in mountain bogs, v) despite lowering of the water table depth during the last decades, Sphagnum rubellum reappeared at the sampling site, vi) decomposition coincided with higher N:P ratios while phosphorus got enriched at the peatland surface, vii) delta C-13 and delta N-15 were not related to average reconstructed water levels, but to the degree of decomposition and the vegetation composition, viii) we see strong indications of a self-regeneration process leading to expansion of oligotrophic Sphagnum species in the bogs of the in bogs of the Harz Mts.

Automated summary

Mountain peatland ecosystems are unique islands of biodiversity that serve as important natural carbon stores. A study of the peatland ecosystem in the Harz Mts. in Germany reveals the impacts of environmental changes, fire, pollution, and human activity on these ecosystems. The study also provides insights into the development of these ecosystems over time.