THE EFFECTS OF PLANTING DENSITY AND FERTILIZATION ON SURVIVAL RATE AND GROWTH OF Cinamomum cassia Blume DURING THE FOREST ESTABLISHMENT PHASE AT LUONG THINH SILVICULTURE EXPERIMENTAL STATION, LAO CAI PROVINCE

Abstract

Planting density and fertilization are crucial factors that significantly affect the growth and productivity of plantation forests. The results of single-factor randomized block design the effects of three planting densities (2,500 trees/ha, 3,333 trees/ha, 5,000 trees/ha) and three rates of basal fertilizer application (0,1 kg NPK/tree, 0,2 kg NPK/tree, and 0,3 kg NPK/tree) at 32 months of age showed that, at this stage, planting density had no significant impact on survival rate, root-collar diameter and total tree height, due to the absence of strong competition for growing space and nutrients. The survival rates in all planting density treatments were above 82%. Significant differences were observed in root-collar diameter and total height among the fertilization treatments. Treatment BP2 was considered the optimal and most effective option, achieving the highest survival rate (91.1%) and the best performances in growth and tree quality indicators (D₀ = 2.73 cm; H_vn = 1.60 m; D_t = 0.58 m). Two major pests and diseases were recorded, namely stem borer and stem fungus, the average damage rate to trees was 4.2% for stem fungus and 2.6% for stem borer. Among them, the stem borer was identified as a serious threat to the plantation and needs appropriate control measures. The research results provide empirical data for adjusting the optimal base fertilizer application rate for Feralit soil sites.