Space Practice Research On Growing Big-diameter Eucalypt--Eucalyptus Urophyla ×Grandis

Space-practice research on developing big-diameter eucalypt wood growth was carried out in this project. It is for the first time domestic report on effect of two practices thinning and wide planting on Eucalyptus urophylla×grandis, one of very outstanding and fast-growing eucalypt hybrids. Three thinning intensities were designed, 60%, 40% and 0%, for stands of initial space of 2000 ha^-1 and 2500 ha^-1, result shows that thinning 60% trees of stand was the best choice for long-term developing average diameter of stand and thinning time was about 4 years since planting. Wide planting trials were analyzed between 6 different spaces over 110 months continued growth. The growth characters are that average diameter, average height, basal area and volume of trees develop rapidly alone with the space extension, but stock. Stand in wide planting could gain great economic benefit from high stock of big-diameter wood in long cutting period. It shows wide planting of space 667ha^-1 could return 45105 yuan ha^-1 totally in 110 months and 1.8 times more than 16389 yuan ha^-1 totally in 62 months under supposed economic calculation methods in this research.