Abstract
A series of field experiments was undertaken to assess changes of some structures in a pasture ecosystem due to cessation of grazing This report deals with the changes of earthworm and white grub populations in the following three experimental plots; Control plot: managed by rotational grazing ; Ca-exclosure plot: prohibited grazing from 1976 to 1979, with CaCO_3 (2 ton/ha) application at the beginning of excluding; Exclosure plot: with no CaCO_3 application. The experimental results obtained were as follows: 1. Populations of earthworms, with Allolobophora japonica and Pheretima sp. increased with cessation of grazing, especially Pheretima sp. increased in Ca-exclosure plot. 2. In control plot, earthworms almost concentrated in the top 5cm soil layer, but in both exclosure plots the considerable numbers were found below 5cm layer. 3. In Ca-exclosure plot, the amount of feces deposited on the soil surface by earth-worms from April to October in 1976 reached 1200g/m^2 dry matter, which was about 60 times as much as in control plot. 4. Populations of larvae of Scarabaeidae decreased with cessation of grazing, especially the decrement in the top 5cm soil layer was marked.
