- Department of Biology, Faculty of Science, Tokyo Metropolitan University, Tokyo, Japan
Energetics of the populations of three isopods,Armadillidium vulgare, Porcellio scaber andLigidium japonicum were studied in a warm-temperate evergreen broadleaved forest of Mt. Kiyosumi in central Japan. The study deals with age composition, survivorship curves, relations of body size to number of eggs or young, and mean growth curves of the populations. Respiratory rates, calorific values and food consumptions of the individual animals were determined in the laboratory. Population density ofA. vulgare was highest of the three species, being about 350/m2 in June 1966. The survivorship curve of theL. japonicum population was more close to L-type than the others. Average total biomass for populations ofA. vulgare, P. scaber andL. japonicum were 3.3 kcal/m2, 0.67 kcal and 0.43 kcal on the monthly basis, respectively. The energy of 35.2 kcal/m2 was estimated to be assimilated by theA. vulgare population, 7.84 kcal byP. scaber and 6.91 kcal byL. japonicum during the period from October 1965 to September 1966. The relations between assimilationA and productionP for fish, grasshopper and isopod populations were found to be expressed asA=aP b . The values of the constanta for the fish, grasshopper and isopod populations seem to be in the range from 10 to 25, from 2 to 7 and from 4 to 8, respectively. Production efficiencies presented asP/A ofA. vulgare, P. scaber andL. japonicum populations were estimated as 19.1%, 15.3% and 13.1%, respectively. The ecological efficiency represented asM/C of these isopod populations was estimated to be in the range from 7.6% to 11. 2%. Reproduction efficiency (Rp/P) ofL. japonicum population was 20%, being the highest value of the three isopod species. This may be related to the L-type survivorship curve ofL. japonicum population. Reproduction efficiency, relating closely to the age structure of the population, is important in the investigation of populations of animals, particularly those that have long life span.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie
- 4 - invertebres
- 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - General Agricultural and Biological Sciences