RESUMO
It is estimated that in the northern hemisphere one-third of the world pool of soil carbon is contained in peat resulting from an incomplete decomposition of plant remains. The time course for the decomposition of the predominant plant litters on a Pennine moorland in northern England is reported for a study extending over 23 years. Spatial variation of the weight remaining of decomposing litters increased with time. This experimental study gave an age for the upper layers of the bog and a curve for long-term decay based on direct observation rather than inferred from profile samples or from short-term observations. It showed that short-term observations can give misleading results in the long term, with a variety of litters with differing early decay rates ultimately making a similar contribution to accumulation. Spatial variation of the weight remaining of the decomposing litters increased with time, so that variation within micro-environments, or within apparantly uniform substrates, may contribute significantly to organic matter accumulation. An asymptotic curve best described the long-term course of decomposition leading to the accumulation of peat. The use of the model for the three litter types, Calluna vulgaris, Eriophorum vaginatum and Rubus chamaemorus, is described and the implication of the results for modelling of organic matter accumulation are then discussed.
RESUMO
Treatment with an antibiotic mixture of penicillin, streptomycin and framycetin freed approximately 60% of individuals of the enchytraeid worm, C. sphagnetorum from living microorganisms and caused no deleterious behavioural changes. Fungi accounted for half of the remaining contamination. Feeding experiments showed that living microorganisms are not an essential requirement for the worm since treated worms grew as well, or slightly better than untreated worms, on both sterile irradiated and non-sterile foods.
