Abstract

Being a key process in nutrient and carbon cycling in coastal ecosystems, decomposition of litter in coastal sand dunes of Orissa was studied in relation to abiotic and biotic factors. Microbial isolation was performed using standard procedures and decomposition of leaf litter was studied using litter bag technique. Higher microbial populations were encountered in soil with cashew plantations compared to barren sand dunes, corresponding with the fluctuation of prevailing temperature and moisture. Micro-fungi of both soils showed a positive correlation with soil moisture but were negatively correlated with soil temperature.  A total of 129 species of fungi belonging to 68 genera were enumerated of which sand dune with cashew plantation had a share of 45 genera, 114 spp. and barren sand dune contributed 51 genera and 112 spp. Sand dune without vegetation revealed 32 restricted spp. while Anacardium plantation soil revealed 34 spp. Trichoderma,Aspergillus and Penicillium are predominant occurrence and have been found to be effective decomposers in the present study.  Rates of litter loss and carbon dioxide output followed the same trends as the fungal numbers. Shannon- Wiener index and richness were higher in soil with Anacardium plantation than the barren sand dune. Maximum fungal population density was observed in the rainy season followed by winter and summer months.  The rate of decomposition was controlled by rainfall, soil temperature, soil moisture, relative humidity and fungal count of soil. This research will help in monitoring the isolation, successful introduction and management of decomposing fungi and their importance in ecosystem service could be a valuable tool for understanding the long term effects of changes in soil condition of the forest floors in coastal sand dunes of Orissa, India.

Key words: Decomposition rate, diversity indices, fungi, abiotic factors, soil respiration.