Applied Soil Ecology 48 (2011) 45–52 Contents lists available at ScienceDirect Applied Soil Ecology journal homepage: www.elsevier.com/locate/apsoil Lignin patterns in soil and termite nests of the Brazilian Cerrado Daniel Rückamp a,∗ , Christopher Martius b,1 , Marcos A.L. Braganc ¸a c , Wulf Amelung a a Institute of Crop Science and Resource Conservation (INRES), Soil Science and Soil Ecology, University of Bonn, Nussallee 13, 53115 Bonn, Germany b Center for Development Research (ZEF), University of Bonn, Walter-Flex-Straße 3, 53113 Bonn, Germany c Department of Biological Science, Federal University of Tocantins, 77500-000 Porto Nacional, TO, Brazil article info Article history: Received 28 October 2010 Received in revised form 2 February 2011 Accepted 8 February 2011 Keywords: Cornitermes silvestrii Nasutitermes kemneri Nasutitermes cf. minor Soil organic matter Mid-infrared spectroscopy Tropical rainforest abstract Organic matter is generally enriched in termite nests. Since lignin resists degradation by most termite species, it could be a prominent tracer of the organic matter incorporated into termite nests and released into nest surroundings. Our objective was to quantify the content and alteration degree of lignin in ter- mite nests and the surrounding soils, and to analyze the development of the lignin status from young to older termite nests. We sampled Cornitermes silvestrii earth mounds and the surrounding soil in an extensive grid scheme in a Cerrado savanna in Central Brazil. Older mounds were secondarily inhabited by Nasutitermes kemneri and other inquilines; those mounds and reference soil sites were also sampled. Lignin contents were estimated by the sum of lignin-derived phenols and additionally by mid-infrared spectroscopy followed by a partial least squares regression. Nests inhabited by primary termites had a lignin content of 1952 mg kg -1 , which was 15 times more than at 10 cm depth of the reference soils. In comparison, organic carbon was only enriched by a factor of 2 in primarily inhabited nests. Our accompa- nying microcosm experiment showed that the lignin composition was not changed during incorporation into termite nests. Elevated lignin contents could still be found at 60 cm distance from the nest border as well as up to 60 cm soil depth beneath the nests. The lignin content in older nests was only half that of younger nests, and the influence on the nest surroundings was less prominent. Higher acid-to-aldehyde ratios in those older nests indicated that the remaining lignin was oxidized and thus partly degraded during nest aging. We conclude that the savanna termite C. silvestrii enriches lignin in its earth mounds, but that only a minor part enters the soil-protected lignin fraction when nests decay, as most of the lignin is lost during nest aging. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Lignin is an organic macromolecule which is part of the sec- ondary cell wall of vascular plants. Typically, 20–30% of the dry mass of wood consist of lignin. Termites feeding on wood use the easily degradable cellulose components rather than lignin as car- bon and energy source (Breznak and Brune, 1994). Several studies showed that those wood-feeding termites and their symbiotic gut microorganisms could only degrade mono- or diaromatic lignin compounds; the core of larger lignin molecules resists degrada- tion (Butler and Buckerfield, 1979; Cookson, 1987; Brune et al., 1995; Kuhnigk and König, 1997). Therefore, lignin is enriched in nests of wood-feeding termites (Hopkins et al., 1998; Amelung ∗ Corresponding author. Current address: Institute of Soil Science, Leibniz Uni- versität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany. Tel.: +49 511 762 2625; fax: +49 511 762 5559. E-mail address: daniel.rueckamp@ifbk.uni-hannover.de (D. Rückamp). 1 Current address: Inter-American Institute for Global Change Research (IAI), Avenida dos Astronautas 1758, 12227-010 Sáo José dos Campos, SP, Brazil. et al., 2002). Lignin in nests of xylophagous termites resisted also degradation when it came in contact with soil material (Cookson, 1992). In contrast to wood-feeding termites, fungus-growing ter- mites are able to consume the lignocelluloses nearly completely, because the symbiotic Termitomyces fungi can degrade lignin to the same degree as other white-rot fungi (Hyodo et al., 2000; Ohkuma, 2003). Studies on other feeding guilds are scarce. It is expected that soil-feeding termites should consume lignin (as part of soil organic matter) more efficiently than wood-feeding termites, but proof is lacking (Breznak and Brune, 1994; Brune et al., 1995; Hopkins et al., 1998). Amelung et al. (2002) could explain the feeding guild of var- ious termite species by the lignin signature of their nests, but did not find indications of different lignin breakdown pathways during food digestion. Due to the fact that no chemical analysis can determine the lignin content in soils exactly, the analysis of phenolic CuO oxida- tion products has been widely used as a standard approach (Hedges and Ertel, 1982; Kögel, 1986; Amelung et al., 1997, 2008). It has the advantage that the lignin content can be estimated by the sum of oxidation products, and that lignin characteristics can be deduced from ratios of individual oxidation products. The ratio of acids to 0929-1393/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.apsoil.2011.02.003