Biomass And Productivity Of E.Urophylla×E.Grandis Planting And Coppies Regeneration Stands On Same Site

This paper studied the biomass and productivity in different regeneration patterns of E.urophylla x E.grandis stands in the same testing field which based on the long period institute of Forestry College of Guangxi University in Dongmen Forest Farm.The results showed that:(1) There was no significant difference of increment of DBH in different regeneration patterns, but had significant difference in increment of height. It showed the significant positive correlation between DBH and tree height that the height was increased with DBH.(2) In different regeneration patterns, there was significant difference in average individual volume and highly significant difference in stand volume. The stand volume of sprout regeneration forest was83.36m3/hm2, and the volume of transplanting seedling forest was125.50m3/hm2. The differentiation of stand individuals of sprout regeneration forest was bigger than the transplanting seedling forest, but the productivity and DBH were opposite.(3) There was significant difference of biomass in different regeneration patterns. The average single-tree biomass of transplanting seedling forest was51.73kg/plant which was42.82%higher than the sprout regeneration forest that was36.22kg/plant.(4) There was significant difference of total stand biomass in different regeneration patterns. The average stand biomass of transplanting seedling forest was76.29t/hm2, which was53.99%higher than the sprout regeneration forest that was49.54t/hm2.(5) The transplanting seedling forest was1.49times of sprout regeneration forest in productivity, and there was significant difference between them.(6) There was no significant difference of vegetation biomass and productivity of different patterns between vegetation under the transplanting seedling forest and the sprout regeneration forest. The average productivity of vegetation under the transplanting seedling forest was4.12t/(hm2.a), and the sprout regeneration forest was4.00t/(hm2.a).(7) The mainly reduction reasons of biomass and productivity of coppies stands were dicreases in soil nutrient by successive rotations, poor in management practices and drought in climate.