STUDY ON THE EFFECTS OF KEEPING TREES AFTER HARVESTING TO THE GROWTH OF Melaleuca leucadendra PLANTATIONS IN THE SECOND CYCLE ON ACID SULPHATE SOIL IN THANH HOA DISTRICT, LONG AN PROVINCE

Abstract

Studying the effects of trees retained after harvesting on growth and productivity of the second-rotation Melaleuca plantations on acid sulphate soils, in Thanh Hoa district, Long An province is a part of the results of the study “Research to complete the technical process of planting and thinning M. leucadendra provides sawn timber in Thanh Hoa district, Long An province”. Conducted from 2020 to 2025. The study has inherited the model of 6-year-old Melaleuca plantations. When harvesting, the tree is retained in cycle 1 with 4 experimental formulas (M0: Clear harvesting - control); M1: retain 100 trees/ha; M2: retain 200 treets/ha and M3: retain 300 trees/ha), the area of each experimental model is 1,500 m² with 3 replicates. On the area of the models, continue to set-up new planting of Melaleuca leucadendra with spare 1 mx1 m. The experiment was collected growth data by the method of positioning plots (100 m²/plot) with 4 formulas (CT0: No keep trees in fist rotation; CT1: retain 100 trees/ha; CT2: retain 200 trees/ha and CT3: retain 300 trees/ha) with 3 replicates. Research results after two years showed that: Regarding the growth of Melaleuca leucadendra plantations in the second rotation, there are parameters of diameter (D1.3), height (H_vn) and reserve after 2 years of age of the formulas. There was no statistically significant difference (P > 0.05). Total yield of models after 2 years of age CT0: 37.4 m³/ha; CT1: 42.7 m³/ha; CT2: 49.0 m³/ha and CT3: 50.7 m³/ha. The model of afforestation, when exploiting and keeping 200 trees/ha and 300 trees/ha, are two promising models for commercial plantation of Melaleuca leucadendra on acid sulphate soil, Long An province.