Yeong Dae Park

Seed quality of Siberian larch (Larix sibirica Ldb.) from geographically diverse seed sources in Mongolia

Abstract The rehabilitation of degraded forests in Mongolia has had very low success and the total successfully reforested area represents only 5% of the total degraded forests. Such poor results may be partly attributed to the low quality of planting stock owing to the poor quality of seeds. The objective of this study was to determine the geographical variation in seed quality of Siberian larch (Larix sibirica Ldb.) from eight different locations in Mongolia. A significant seed source variation was observed in seed quality traits, such as seed weight, viability, germination capacity, germination energy and seedling emergence. In the present study, some of the characters were correlated with geographical and climatic factors including longitude, latitude, altitude, temperature and precipitation of the location of seed origin or collection sites. On the basis of these results, it may be concluded that source 5 (Binder) and source 6 (Huvsgul) were superior among the seed sources studied in terms of seed quality. Therefore, it is advisable that these seed sources be used for collection of the bulk quantity of seeds to achieve better productivity and more vigorous seedlings.

Effects of Enrichment Planting with Five Native Species and Different Plantation Treatments on Seedling Growth Characteristics at Logged-over Forest in Lao PDR

Enrichment planting is commonly used for increasing the density of tree species in secondary forests and one of forest rehabilitation programs in Lao PDR. This study aimed to determine the performance of five native species in enrichment planting using different canopy opening treatments, and to examine the suitable species and silviculture techniques applicable to a logged-over forest in Lao PDR. Results of the study showed that only crown height had significant difference among species and planting treatments. The survival rate and crown diameter were significantly different by species, but not by planting treatments. However, root collar diameter (RCD) and height of seedlings showed significant differences among planting treatments. Among the study species, Hopea odorata and Dalbergia cochinchinensis showed significantly higher survival rate and height growth, indicating their suitability in enrichment planting for rehabilitation of forest in Lao PDR. The results also suggested that 2 m width line planting stimulated RCD growth, but wider line planting, such as gap planting, promoted height growth of seedlings.

Carbon storage of 15-year-old Xylia xylocarpa and Pterocarpus macrocarpus plantations in the Katha District of Myanmar

This research was conducted in the Katha District of Myanmar to compare the biomass (carbon) allocation of Xylia xylocarpa (Roxb.) W. Theob. and Pterocarpus macrocarpus Kurz species and to investigate the carbon content of the undergrowth vegetation, litter layer, and soil at these two plantations. A total of 40 trees from both species were selected to estimate the biomass allocation in each component of a tree. The estimated biomass (carbon) allocation for X. xylocarpa was 7.8% in the leaves, 22.2% in the branches, 52.2% in the stems and 17.8% in the roots while the estimated biomass (carbon) allocation for P. macrocarpus was 2.8% in the leaves, 24.4% in the branches, 61.3% in the stems and 11.5% in the roots. The study discovered that the biomass of the trees at the X. xylocarpa plantation (80.4 tons ha−1) was higher than that at the P. macrocarpus plantation (77.2 tons ha−1). The total carbon content at the P. macrocarpus plantation (130.8 tons ha−1) was significantly higher than that at the X. xylocarpa plantation (120.5 tons ha−1). Likewise, the mean annual increment (MAI) of the carbon content in the X. xylocarpa plantation was estimated at about 2.7 tons ha−1 while the P. macrocarpus plantation accounted for 2.5 tons ha−1. This study suggests that it is very important in the management of plantations to focus not only on the planted trees but also on the undergrowth vegetation, litter layer and soil layer, which play a significant role in the stand-level carbon content.