Soil organic carbon stocks, distribution, and composition affected by historic land use changes on adjacent sites

Carsten W. Mueller, Ingrid Koegel-Knabner

Research output: Contribution to journalArticlepeer-review

89 Scopus citations

Abstract

Historic alterations in land use from forest to grassland and cropland to forest were used to determine impacts on carbon (C) stocks and distribution and soil organic matter (SOM) characteristics on adjacent Cambisols in Eastern Germany. We investigated a continuous Norway spruce forest (F-F), a former cropland afforested in 1930 (C-F), and a grassland deforested in 1953 (F-G). For C and N stocks, we sampled the A and B horizons of nine soil pits per site. Additionally, we separated SOM fractions of A and B horizons by physical means from one central soil pit per pedon. To unravel differences of SOM composition, we analyzed SOM fractions by 13C-CPMAS NMR spectroscopy and radiocarbon analysis. For the mineral soils, differences in total C stocks between the sites were low (F-F∈=∈8.3 kg m-2; C-F∈=∈7.3 kg m-2; F-G∈=∈8.2 kg m-2). Larger total C stocks (+25%) were found under continuous forest compared with grassland, due to the C stored within the organic horizons. Due to a faster turnover, the contents of free particulate organic matter (POM) were lower under grassland. High alkyl C/O/N-alkyl C ratios of free POM fractions indicated higher decomposition stages under forest (1.16) in relation to former cropland (0.48) and grassland (0.33). Historic management, such as burning of tree residues, was still identifiable in the subsoils by the composition and 14C activity of occluded POM fractions. The high potential of longer lasting C sequestration within fractions of slower turnover was indicated by the larger amounts of claybound C per square meter found under continuous forest in contrast to grassland.

Original languageEnglish
Pages (from-to)347-359
Number of pages13
JournalBiology and Fertility of Soils
Volume45
Issue number4
DOIs
StatePublished - Mar 2009

Keywords

  • Black carbon
  • C-CPMAS NMR
  • Density fractionation
  • Particulate organic matter
  • Radiocarbon

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