CIES COMPOSITION AND PHYTOMASS OF UNDERGROWTH DIFFERENT KIND OF TREES AND SPACINGS IN FOREST PLANTATION

Abstract

The study on phytomass of the undergrowth in Melia azedarach Linn. and Eucalyptus camaldulensis Dehnh. plantation at Ongphra Reforestation Unit, Suphanburi, was carried out during May 1983 to December, 1984. The results indicate that there was 316 gm.^-2 of undergrowth phytomass in the plantation, about 72.8 percent of phytomass occur during the rainy season while the rest of 27.2 percent represent the phytomass in the dry season, Pennisetum polystachyon Schult. and Eupatorium odoratum Linn. were the main species comprising of more than 80 percent of the total phytomass, There was a great variation on each sampling date and no specific pattern was found. The trend of undergrowth phytomass was directly related to rainfall. The undergrowth phytomass in the Melia azedarach plantation was more than that of Eucalyptus camaldulensis but it was non  significant difference (P> 0.05). However, there was a significant difference (P < 0.01) of the undergrowth phytomass between 4 X 4 m and 2 X 8 m spacings. Therefore, if one would like to apply the agroforestry system into the management practices in the forest plantation, the proper spacing should be 2 X 8 m rather than 4 X 4 m. The substitution of the evergreen and more nutritive forage species to the native species should be considered important especially the species in the Leguminosae Family.