Effect of Environmental Factors on the Growth and Survivability of Planted Shorea macrophylla along Riverbanks of Batang Kayan Ulu, Lundu, Sarawak

Reforestation is essential in preventing further loss of biodiversity especially under the tropical ecosystem. The success of reforestation depends largely on factors such as optimum sunlight exposure, water quality, climate regulation and soil conditions in the area. This study was conducted at Batang Kayan Ulu, Lundu, Sarawak to evaluate and estimate the growth performance, survival, amount of total above-ground biomass and carbon stock of planted Shorea macrophylla after enrichment planting at different age stands as well as to investigate the effects of environmental factors (soil compaction and light intensity) on the growth and survivability of planted Shorea macrophylla. Survival, diameter at breast height (DBH), total height, basal area and volume; mean annual increment in diameter, height, volume; above-ground biomass, carbon stock and relative light intensity were measured. The findings implied that the growth performance in terms of average in diameter at breast height, volume, mean annual increment in diameter as well as total above-ground biomass and carbon stock in Plot SPD96 was the highest and showed the most favourable growth as compared to Plot SPD97, SPD98 and SPD99. SPD96 with 84% of survival was the highest among all study plots surveyed followed by SPD97 with 77%, SPD98 with 70% and SPD99 with 55% of survival. Nonetheless, average height, basal area and mean annual increment in height in SPD97 revealed the highest value meanwhile mean annual increment in volume in SPD98 displays the highest among all study plots. Soil penetration resistance and soil compaction in SPD98 and SPD99 plots were higher as compared to SPD96 and SPD97 plots. This was essentially due to the presence of gravel materials and accumulation of stagnant water nearby the river. High survival and substantial growth performance of S. macrophylla implied that microclimate condition such as competition between planted with existing pioneer species and edaphic factors may have affected the planted Shorea macrophylla. Further studies on other environmental factors, experimental reforestation at early stage of establishment in nursery, long-term monitoring period of growth performance and light condition should be implemented