THE INVESTIGATION AND ANALYSIS ON SITE CONDITION AND GROWTH OF GMELINA ARBOREA

The result of investigation and analysis showed that, the tropical and the south-subtropical below 23.5°N in China, the annual mean temperature is 20.5-24.5℃ the extreme minimum temperature-1.5℃, the mean annual rainfall 1200-2200mm, is the most suitable region for growth of Gmelina arborea.It demands the habitat with topography wide, sunshine abundance, gentle breeze (the ten days average wind speed2 m/second), loose soil structure, humus content2%, total nitrogen0.l%, available phosphate0.25mg/100g soil, pH 4.5-6.9, moisture content 10-24% of the surface layer soil.The growth effect of young plantation is significantly different in different kinds of vegetation types and slop position.The results of correlation analysis showed, in a certain range, that the growth of Gmelina arborea has respectively extremely significant positive correlation of linearity, power function, exponential function and S curve with pH value, moisture content, nutrient(N,P), but the available phosphate is a more important factor for the tree growth than the others.