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International Journal of Ecology and Environmental Sciences 27: 31-38, 2001
International Scientific Publications, New Delhi

Decomposition of Oak and Willow Leaves in Two Lakes of Kumaon with Different Trophic Characteristics

P.K. Gupta, Rajani Dangwal and Surendra S. Nagdali

ABSTRACT

Decomposition of oak and willow leaf litter was investigated during 1996-1997 in Lake Nainital (hypereutrophic) and Lake Bhimtal (mesotrophic). In both the lakes willow leaves decomposed significantly faster than oak leaves. After three months, ~3% of willow leaf were left in the two lakes while >50% of oak leaves were left after 10 months of inundation. Decomposition of oak leaves was slower in Lake Nainital. The ratios of breakdown coefficients revealed that the 'leaf species effect' was 17 to 27 times greater than the 'lake effect'. The macroinvertebrate densities were consistently higher on leaf litter incubated in the Nainital Lake. The maximum number of invertebrates reached 171 ind g1 oak leaf material and 82 ind g1 willow leaf material in Lake Nainital and 138 ind g1 oak leaf and 47 ind g1 willow leaf in Lake Bhimtal. In both the lakes and on both the litter substrates, chironomid larvae and tubificid worms were chief constituents of the fauna. The slower breakdown of leaf litter in Lake Nainital with greater number of macroinvertebrates colonization than in Lake Bhimtal may be due to lower number and activity of microorganisms community associated with decomposing litter, high rate of siltation, and lower mechanical breakage caused by slower wave action in this system.

Key Words
: Oak, Willow, Decomposition, Kumaon Himalaya, Macroinvertebrates, Lake Nainital, Lake Bhimtal.