Environment, Rate of Growth, Effect of Intercultivation and Volume Production in Dalbergia sissoo and Eucalyptus camaldulensis Plantations at Sagarnath (Nepal)

The Sagarnath Forestry Development Project is the largest mechanised plantation initiative in Nepal. Of the 11000 ha planted, around 55% is Eucalyptus and 40% Dalbergia sissoo. In all 20 sites (8 planted with D. sissoo and 12 planted with Eucalyptus) were taken up for study of the diameter and height growth. Most of the plantations were-intercuItivated for periods varying from 1 to 5 years. The age of D. sissoo plantations ranged from 3 to 25 years while those of Eucalyptus was from 3 to 13 years. Regression equations for Age/Diameter and Diameter/Height were established for both the species under intercropped and not intercropped conditions. It was observed that intercropping gives initially good start to the plants, however in the long run, the growth is determined by the site potential and the impact of intercropping is nullified. It was seen that upto the age of 3 years the diameter gTowth of both Eucalyptus and D. sissoo was equal while between 3 to 11 years Eucalyptus had better growth than D. sissoo. However thereafter D. sissoo has better diameter growth. Regarding volume (O.B.) production in Eucalyptus the average scenario from the (8-13 years age) data of Eucalyptus gave productivity of 15.86 m³/ha/year while the best scenario (9 years of age) gave a figure of 31.01 m³/ha/year and the worst scenario gave a figure of 6.44 m³/ha/year for 13 years old plantation. In case of D. sissoo the average Volume (O.B.) production at 15 years was 11.17 m³/ha/year and at 25 years it was 15.35 m³/ha/year.