<S1-2> Effects of enrichment planting on the soil physicochemical properties at reforestation sites planted with Shorea macrophylla de Vriese in Sampadi Forest Reserve, Sarawak, Malaysia

This proceeding is a compilation of findings and progress activities of research collaboration between the Forest Department Sarawak (FDS) and the Japan Research Consortium for Tropical Forests in Sarawak (JRCTS). To highlight the research findings, An International Symposium entitled "Frontier in Tropical Forest Research: Progress in Joint Projects between the Forest Department Sarawak and the Japan Research Consortium for Tropical Forests in Sarawak" was ii held in Kuching, Sarawak on 21-22 September 2015.A preliminary assessment on the soils in reforestation sites at Sampadi Forest Reserve, Sarawak was conducted to clarify and compare the effects of enrichment planting on the soil physicochemical properties within the reforested areas and adjacent secondary forest. Reforestation areas which were planted with Shorea macrophylla de Vriese by the line planting technique were selected in this study. The study sites were stands reforested in different years (SM96 in 1996; SM97 in 1997; SM98 in 1998; and SM99 in 1999) and an adjacent secondary forest (SF). Undisturbed and composite soil samples were collected at the depth of 0-10 cm (surface soils) and 30-40 cm (subsurface soils) from several random points. We found that the soils at both reforestation sites and secondary forest were strongly acidic, with pH of less than 5.5, with low nutrient status. Soil total carbon in secondary forest was significantly higher than that of the reforestation sites, indicating that a large pool of fresh organic matter was derived from the above vegetation in the surface soil. Notwithstanding, significant differences were observed in soil available phosphorus between the sites in both surface and subsurface soils. In terms of the soil physical properties, the soils observed were relatively of sandy clay loam to sandy clay in texture, and did not vary widely, including their low fertility level, among the studied sites. Based on the current findings of this study, enrichment planting after 15 years might help slightly to restore the productivity of certain soil physicochemical properties at the reforestation sites