Ecological energetics of populations of four sympatric isopods in a Hong Kong forest

Population energy budgets of four sympatric isopods, Burmoniscus ocellatus, Burmoniscus sp. (Philosciidae), Fortnosillo raffaelei and Orodillo maculatus (Armadillidae), were calculated at two sites in a Hong Kong mixed forest. Mean population standing stock of the four species ranged from 1.25 to 13.61 kj m^-2. Mean total isopod biomass at the two sites was 0.85 and 1.85g m^-2. Annual production of the four species varied from 4.24 to 30.43 kj m^-2with 5.2-26.4% (energy content) allocated to reproduction. Annual production of the four species combined at the two sites was 23.22 and 50.15 kj m~². P/B ratios varied from 2.24 to 4.27. Annual population consumption on mixed litter by the four isopod species ranged from 28.4 to 183.0kj m^-2. Total annual consumption by all species at the two sites was 233.7 and 360.2 kj m^-2(1.96 and 2.53% of annual litter fall). lsopod respiratory rates were proportional to body weight, with an exponent ranging from 0.68-0.78 at 23°C. The annual population metabolism of the four species varied from 14.62 to 86.11 kj m^-2. Total annual isopod metabolism at the two sites was 116.33 and 185.95 kj m^-2. These results are discussed with reference to the role of isopods in litter breakdown and energy flow in the Hong Kong forest.