Lignin characteristics and density fractions of termite nests in an Amazonian rain forestÐindicators of termite feeding guilds? Wulf Amelung a, * , Christopher Martius b , Adelmar G. Bandeira c , Marcos V.B. Garcia d , Wolfgang Zech a a Institute of Soil Science and Soil Geography, University of Bayreuth, D-95440 Bayreuth, Germany b Center for Development Research (ZEF), Walter-Flex-Str. 3, 53113 Bonn, Germany c Departamento de Sistema ÂticaeEcologia,CentrodeCie Ãncias Exatas e da Natureza, Universidade Federal da Paraiba, 58059-000 Joa ÄoPessoa,PB,Brazil d Embrapa Amazo Ãnia Ocidental, c.p. 319, 69.011-970 Manaus, AM, Brazil Received 22 February 2000; accepted 27 September 2001 Abstract Hightermiteabundanceanddiversityinrainforestsresultsinthecreationofdifferenttermitenests,whichareformedfromexcretedfood waste. The objective of this study was to elucidate the properties of nest material of common rain forest termites by analysing residues of potential food sources. In the Amazonian rain forest near Manaus, Brazil, we sampled nests of six different termite genera as well as surrounding wood, microepiphytes and soil. After a density separation into ,1.6,1.6±1.8,1.8±2.0,2.0±2.4,and .2.4gcm 23 fractions, we determinedthecontentsofC,N,andlignin-derivedphenolsinthesamples.Asparticledensityincreased,theelementandligninconcentra- tions decreased in all samples, the remaining lignin showed evidence of increased side-chain oxidation P , 0:05: The termite nests contained7.3±22timesmoreC,14±220morelignin-derivedphenols,and5.6±260timesmorelightfractionmaterialthanthesurrounding surfacesoils(0±10cm).Thenestsofthewood-feedingguildcontained1.2±15timesmoreligninand1.1±46timesmorelightmaterialthan those of the soil/wood-interface feeders. Among the different nests, the particle density increased in the order Nasutitermes sp. , Cornitermes sp. , Termes sp. , Embiratermes sp. , Anoplotermes sp.(,soil). In the same direction the content of lignin-derived phenols decreasedfrom111to3gkg 21 nestmaterialandamountedto0.5gkg 21 soil.Theresultsindicatedashiftfromwoodtosoilmaterialinthe nests. Nests of Constrictotermes sp. had low lignin content despite high proportions of the light material. This indicated feeding on microepiphytes. We conclude that variations in lignin characteristics and density fractions of termite nests re¯ect differences in feeding guilds of the studied taxa. q 2002 Elsevier Science Ltd. All rights reserved. Keywords: Soil organic matter; Lignin; Density fractions; Rain forest; Termites 1. Introduction Understandingtheroleoftermitesinecosystemfunction- ing requires knowledge of their feeding habits. This is especially true for rain forests, where termite abundance and diversity are higher than in other ecosystems of the world (Martius, 1994; Bignell and Eggleton, 2000). The food sources of termites are diverse, varying from wood at different decomposition stages (xylophagous termites), soil organic matter (humivorous termites), or both (soil/wood- interface feeders). However, also microepiphytes growing on tree trunks (possibly Constrictotermes sp., South America), litter (leaf litter harvesters), grass, bark, fungi, and algae are consumed (Lee and Wood, 1971; Martius, 1994; Bignell and Eggleton, 2000). A food differentiation amongtheclassofsoil/wood-interfacefeedingtermiteswas not detected. Investigating the feeding habits of termites in the rain- forestisdif®cult,duetothehighvariabilityofpotentialfood sources and restriction in current methods of feeding iden- ti®cation. Ridges at the mandible surface may only roughly be used as indicators for wood or soil feeding (Deligne, 1966), and feeding experiments may not be representative (Lee and Wood, 1971; Bustamante and Martius, 1998). An identi®cation of soil, wood, and soil/wood-interface feeders was achieved by analyses of gut contents (Sleaford et al., 1996) or tissue isotopic composition (Tayasu et al., 1997) but complications arise from the temporal heterogeneity of the gut material, differences between foraging parties and signi®cant proportions of living microbial biomass (Varma et al., 1994; Sleaford et al., 1996). In contrast, termite Soil Biology & Biochemistry 34 (2002) 367±372 0038-0717/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved. PII:S0038-0717(01)00192-4 www.elsevier.com/locate/soilbio * Corresponding author. Tel.: 149-921-552146; fax: 149-921-552246. E-mail address: wulf.amelung@uni-bayreuth.de (W. Amelung).