STRUCTURAL CHARACTERISTICS OF PINE STANDS AT BAN WAT CHAN ROYAL PROJECT, CHIANGMAI PROVINCE

Abstract

The study site of this investigation was located at Ban Wat Chan Royal Project, Mae Chaem district of Chiangmai province where natural pine stands occur at about 1,000 m above mean sea level. The stands were identified into 3 categories based on the dominant species of upper storey: P. merkusii forest, P. kesiya forest, and P. merkusii-P. kesiya forest. The investigation was carried out in mid-November 1987 by systematic random sampling of 20 plots of 10x10 m², 4x4 m², and 1x1 m² in size for tree, sapling, and seedling data collection; respectively, making the total temporary plots of 60 in each stand. Vertical structure was studied in a plot of 10x40 m² plot size in each stand. The results showed that the species numbers of P. merkusii forest, P. kesiya forest, and mixed forest of P. merkusii and P. kesiya were of 22, 31, and 28, respectively. Mixed stand was found to have the maximum species diversity while the minimum was recorded for P. merkusii forest. Stand densities of P. merkusii, P. kesiya, and mixed forests were of 255, 270 and 280 trees/ha, respectively with the basal areas of 25.3208, 20.3158. and 19.1924 m²/ha, respectively. Dipterocarpus tuberculatus was found to have the highest important value index in P. merkusii forest, while P. kesiya in P. kesiya forest, aud D. obtusifolius in mixed forest. Grasses showed the highest important value index among undergrowth species. Similarity index between P. merkusii forest and mixed forest had the highest value, while that of P. merkusii forest and P. kesiya forest had the lowest ones. Percentages of crown cover of pine forests studied varied from 52.88 to 66.54 with 2 canopy layers, pines in the top tier. Natural regeneration of this pine stand was considered as unsatisfactory level, since only seedling stage was observed to be well distributed, but not in sapling and poling stages, resulted to the small amounts of saplings and polings in comparison to the amounts of seedlings found in the stands.