Spatial Distribution Patterns and Characteristics of Gaps under Tropical Forest Stages in the Central Highlands, Vietnam

Abstract: Gaps have a significant influence on forest structure and development. This study analysed characteristics of gaps between secondary and old–growth forests in Kon Ka Kinh National Park, Gia Lai Province, Vietnam. One hectare inventory plots were established in each forest stage. Data on gap size, coordinates, average height of surrounding trees, slope and directions of main axes were recorded. Results showed that the secondary forest had slightly higher number of gaps, compared to old–growth forest. However, the average size of gaps was smaller. Frequency distributions were significantly different between the two forest stages. The size of the gaps correlated with the height of the surrounding forest canopy but there was no correlation with slope. The length direction of gaps was most concentrated at East–North–East in both forest types. The distribution of gaps were regular at a scale of 0 to about 15 m, but were random at larger distances. The gap size spatial distribution was random in the secondary forest, but 60% of plots in the old–growth forest were affected by neighbouring gaps. The findings suggest that assisted natural regeneration, enrichment planting and gap–size extension should be undertaken in these secondary forests to increase forest quality.