Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan Plateau. For all northern peatlands, carbon content in organic matter was estimated at 42 ± 3% (standard deviation) for Sphagnum peat, 51 ± 2% for non- Sphagnum peat, and at 49 ± 2% overall. Dry bulk density averaged 0.12 ± 0.07 g/cm3, organic matter bulk density averaged 0.11 ± 0.05 g/cm3, and total carbon content in peat averaged 47 ± 6%. In general, large differences were found between Sphagnum and non- Sphagnum peat types in terms of peat properties. Time-weighted peat carbon accumulation rates averaged 23 ± 2 (standard error of mean) g C/m2/yr during the Holocene on the basis of 151 peat cores from 127 sites, with the highest rates of carbon accumulation (25–28 g C/m2/yr) recorded during the early Holocene when the climate was warmer than the present. Furthermore, we estimate the northern peatland carbon and nitrogen pools at 436 and 10 gigatons, respectively. The database is publicly available at https://peatlands.lehigh.edu .
Proxy-climatic data in the form of plant macrofossils have been analysed from a 5 m core from Bolton Fell Moss, Cumbria, UK. Detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years. The record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog-surface wetness for the latter half of the Holocene. As bog- surface wetness is directly controlled by the prevailing climatic conditions, this reconstruction can be viewed as a proxy-climate record. Twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12.4 yr cm-1 . The regular sampling intervals thus provide a time series of past bog-surface wetness; spectral analyses of this series indicates that wetness changes are cyclic, with a ca. 800 year periodicity.
Plant macrofossil data have been used to identify the successive mire communities occupying both central and marginal locations in the Walton Moss peatland complex, during the last 10 500 years. The reconstructed pathways of mire development indicate that early-Holocene fen and fen-carr communities were succeeded by species indicative of deep mire water tables and oligotrophic conditions. The character of the fen/bog transition (FBT) is compared with similar records of peatland development from Britain and Scandinavia and with independent climate data for the early Holocene. The ‘pseudohochmoor’ of central Europe is suggested as an approximate modern analogue for the dry pioneer oligotrophic mire type and alternative explanations for its presence are explored. The first major increase in ombrotrophic Sphagna occurred at c. 7800 cal. BP. Overlying Sphagnum peats provide a continuous record of climate change, inferred from fluctuations in raised mire surface wetness. The proxy palaeoclimate record, reconstructed using Detrended Correspondence Analysis, registers wet shifts commencing at c. 7800, c. 5300, 4410–3990 (2s range), c. 3500, 3170–2860 (2s range), 2320–2040 (2s range), c. 1750, c. 1450, c. 300 and c. 100 cal. BP. This climate record is compared with a similar one from Bolton Fell Moss and spectral analysis of the time-series gives periodicities of c. 1100 years and c. 600 years between wet shifts.
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