Abstract

Decomposition of leaf litters of Tectona gradis, Eucalyptus tereticornis and Albizia falcataria was studied using the mesh bag technique for a period of 18 months under field and laboratory conditions. The decay rate of the three litters also varied significantly under both laboratory and field conditions. There was positive correlation between loss in weight of litters, litter moisture content and rainfall; decomposition of all the litters was rapid during south-west monsoon. CO2 evolution from decomposing litters differed significantly between the three species and it was significantly higher in the field than in the laboratory. CO2 evolution was highest during south-west monsoon. During the study period, there was no significant addition of organic carbon to soil from decomposing teak, Albizia and eucalypt litters under laboratory conditions. The addition of OC to soil from eucalypt litter was relatively lower than that from the other two species. In general, the population of various microorganisms associated with the decomposing litters was significantly lower on eucalypt than that on teak and Albizia. There were significant differences between number of fungi per g of Albizia and eucalypt litters. The population of actinomycetes showed distinct differences between teak and eucalypt. Among the fungi colonizing the different litters, the fungi imperfecti were predominant as they showed higher percentage distribution in comparison with others. The members of Zygomycetes and Ascomycetes were poorly represented and can be considered as weak colonizers. It is concluded from the results of this study that 1) the leaf litter of eucalypt is relatively resistant to decomposition in comparison with those of teak and Albizia. 2) litter moisture content is crucial for the decomposition leaf litters. 3) the rate of decomposition of litters and the microbial acitivity are higher in the field than in the laboratory. 4) the fungal succession on decaying litters reported here is similar to the general scheme of fungal sucession on plant litters proposed by Hudson, and 5) the substrate quality is the major factor which determines the rate of leaf litter decomposition, CO2 evolution, the density of microorganisms associated with the litters and also composition of their fungal floras