Peat growth and carbon accumulation rates during the holocene in boreal miresKlarqvist, Malin
This thesis is based on the analysis of peat stratigraphies to study peat growth and carbon accumulation processes in northern mires. In the first study, problems concerning l4C dating of peat were examined by fractionation of bulk peat samples and l4C AMS dating of the separate fractions. In the following studies, peat cores from twelve Swedish mire sites were investigated. Macrofossil analysis was performed on the sampled cores to describe and classify the plant communities during mire development. Between 6 to 18 l4C AMS datings were performed on one core from each mire in order to estimate the peat growth and carbon accumulation rates for the identified plant communities.
Different fractions within single peat bulk samples gave considerably differing l4C ages. The range in age differed between mire types and depth. For accurate l4C dating, moss-stems, preferably of Sphagnum spp. are recommended (Paper I). Both autogenic and allogenic factors, e.g. climate and developmental stage, respectively, were identified as important influences on carbon accumulation (Paper II). Both peat growth and carbon accumulation rates differed between plant communities. The major factors explaining the variations in accumulation rates of the different plant communities were the amount of Carex and Sphagnum remains and the geographical position of the mire (Paper IV). Carbon accumulation rates decrease along with development in most mires. The results indicate that some mires may have alternated between being carbon sinks and sources, at least over the last several hundred years. The inter-annual variation in carbon accumulation is probably explained by climatic variations (Paper III).
Keywords14C AMS dating; allogenic; autogenic; carbon turnover; Carex; mires; eatlands; Sphagnum
Published inActa Universitatis Agriculturae Sueciae. Silvestria
2001, number: 203
Publisher: Department of Forest Ecology, Swedish University of Agricultural Sciences
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