Abstract
Aboveground biomass and net production rates of a young Salix subfragilis community were studied in an abandoned paddy field at Shimagahara, Mie Prefecture. The estimated leaf biomass (3.18 t/ha) and LAI (4.75 ha/ha) coincided with the mean values for deciduous broadleaved forests in Japan. The stem and branch biomass increased from 44.10 t/ha to 56.82 t/ha during the growing season in 2003. The net production rate was estimated to be 20.32 t/ha/yr as the total of three components: the biomass increment calculated as the difference between the biomasses during the same 2003 period (12.72 t/ha/yr), the loss due to the death of trees and their parts (7.42 t/ha/yr), and the loss due to grazing by insects estimated from the fall rates of insect feces (0.18 t/ha/yr). This production rate was far larger than the mean value for deciduous broadleaved forests in Japan, although high production rates equivalent to that of the study community have been reported for young forests. The aboveground biomass density (dry weight divided by the 3-D space occupied by the plant community) calculated from the estimated maximum biomass in summer (60.0 t/ha) and the mean height of dominant trees (8.8 m) was 0.68 kg/m3, which is close to those of several communities of other shade-intolerant trees.
