Abstract:
Population variation of fungi and bacteria in different aged Eucalyptus
grandis plantation forest soil was studied. Plantations aged 7, 13, 22 and 30
years and adjacent tea estate, abandon Eucalyptus planted site (without
plants) and natural forest were selected as study sites from Passara, Uva
Province area. Necessary parameters were considered to minimize
microclimatic variations among the field sites. Soils were collected using a
soil auger cleaned with 90 % alcohol from top layer (0-15 cm layer). The soil
extractions were prepared in dilution series and cultured using Potato
dextrose agar and nutrient agar and microbial count was taken. Eucalyptus
plantations showed lower amount of fungal populations compared to other
sites. The 30 years old Eucalyptus plantation had the highest amount of
fungal population (953±122 MPN g
-1
) compared to other Eucalyptus
plantations. There were significant relationship between fungal population
and stand age of Eucalyptus plantation (p<0.0001; R2
= 98.44 %). But the
stand age is not significantly affected to bacterial population (p > 0.05). So
mainly because of fungal population, fungi to bacteria ratio (F: B) in soil
varied with plantation‟s stand age. The low F : B indicated that Eucalyptus
plantation forests are bacteria dominant. This study suggest that fungal
population is more sensitive than bacterial population to the stand age related
factors in soil such as nutrient content and understory, which could be
important in sustainable management and restoration of Eucalyptus
plantation soils for a better yield.
