Incorporating agroforestry practices in Karas (Aquilaria malaccensis) plantations in Malaysia

Analysis on tree growth data and survival rate from a 6-year old Karas agroforestry plantations in Rembau, Negeri Sembilan, Malaysia is reported in this paper. Three agroforestry components involved in this study include: (1) Karas monoculture, (2) Karas intercropped with lemongrass, and (3) Karas intercropped with guava. Three replicative plots measuring at 6 rows × 5 column of trees were established for each component. The diameter at breast height (DBH) of each component was measured within four time intervals while height was measured within two time intervals which produced three sets and one set of growth, respectively. From the field measurements, the DBH growth were 0.65, 0.71 and 0.95 cm respectively while the height growth were 6.82 and 12.21 m respectively. The means of DBH of Karas for the three components ranged from 1.94 to 2.90 cm with means of height ranged from 3.96 to 7.59 m. These translated into the Periodic Anual Increment (PAI) of diameter and height which were ranged from 1.74 to 2.43 cm/year and 3.47 to 6.65 m /year, respectively. From the analysis of variance (ANOVA), it was found that there is a significant difference in the means DBH and height of Karas among different components and growth interval (P≤0.05). From t-test analysis, there is a significant difference between the first and the second height growth measurements (P≤0.05). However, there is no significant difference in the survival rate among all components (P≥0.05). This concludes that there appear to be intercropping effects in the growth of a 6-year old Karas agroforestry system. The results from this study will be used for subsequent investigation in the assessments of growth performance of Karas under different intercropping components.