Outplanting Performance of the Bornean Tropical Indigenous Species Shorea macrophylla (de Vriese) P. S. Ashton in relation to Seedling Age

Planting high-quality seedlings with desirable growth attributes are associated with successful survival and growth performance following outplanting. Considering that most tree species from the Dipterocarpaceae family are on the IUCN Red List of *reatened Species, proper conservation of such species is necessary. Very little is known with no clear consensus regarding whether increasing the seedling production period enhances outplanting survival and growth potential of tropical dipterocarp species planted under enrichment planting in Malaysia. In this study, one potential Bornean tropical indigenous species, Shorea macrophylla (de Vriese) P.S. Ashton, was produced in the Universiti Malaysia Sarawak nursery and outplanted at Sampadi Forest Reserve, Sarawak. Different nursery production periods (3, 6, 9, and 24 months) were tested for the species at the time of planting as well as for the subsequent growth performance after 12, 24, and 42 months of outplanting. *e findings revealed that older (9-and 24-month-old) S. macrophylla seedlings were morphologically larger from younger (3- and 6-month-old) seedlings. Nonetheless, the overall pooled mean survival rates declined from 61.7 to 44.6% after 12, 24, and 42 months of outplanting. For the 42-month period, the survival rate for the 9-month-old seedlings was significantly higher than that for the 3-, 6-, and 24-monthold seedlings. Notwithstanding, the relative growth rate of the stem diameter was higher for the 3- and 9-month-old seedlings than for the 6- and 24-month-old seedlings after 42 months of outplanting. *us, maintaining plant material from the seedlings produced at 3, 6, and 9 months of age would be beneficial for the initiation of transplantation in restoration programmes in Sarawak. *e 24-month-old seedlings will also be useful, especially during irregular flowering and unpredictable fruiting intervals. A further experimental study on other environmental factors that could influence the outplanting performance of the seedlings in the tropical forest restoration area of Sarawak, Malaysia, is necessary

Allometric Equations to Estimate the Aboveground Biomass of Seedling and Sapling Plants in 10 and 20 Years Old of Secondary Forests in Sarawak, Malaysia

The seedlings and saplings plant stage determines the successional stages in the secondary forest establishment process. The estimation on aboveground biomass (AGB) of seedling and sapling plants is needed to describe undergrowth's contribution in the secondary forest. This study's objective was to develop allometric equations for accurate estimation of AGB for seedlings-saplings in 10 and 20 years old of secondary forests. The study was carried out at sites with two stages of the fallow period: lands with a fallow period of 10 and 20 years, respectively, in Sarawak, East Malaysia. The AGB data of all selected seedlings and saplings with the different species within 100 sample quadrates were used to develop allometric equations for seedlings and saplings in each study site. This study developed allometric equations to estimate AGB of seedlings-saplings (diameter at the ground surface of < 5 cm), particularly in 10 and 20 years of fallow ages

Estimating Soil Fertility Status Using Soil Quality Indices At Reforestation Sites In Sampadi Forest Reserve, Sarawak, Malaysia

Soil fertility status can be estimated by using appropriate soil quality indices in order to provide fundamental information on the land suitability for reforestation activities. A study was conducted to characterize the soil physicochemical properties and to clarify the current soil fertility status using soil quality index for estimating soil fertility of more than 15 years after the initiation of forest rehabilitation at Sampadi Forest Reserve, Sarawak. Study plots with the size of 75 m x 50 m were established in the reforestation areas of different age stands (planted with Shorea macrophylla in the year 1996; SM96, 1997; SM97, 1998; SM98 and 1999; SM99) and outside reforestation area (secondary forest, SF). Composite and undisturbed soil samples were collected at the depth of 0-10 cm (surface soils) and 30-40 cm (subsurface soils) from several random points at plots in reforested areas and secondary forest for determination of the soil physicochemical properties. The soil fertility status was evaluated and quantified using two soil indices, Soil Fertility Index (SFI) and Soil Evaluation Factor (SEF). Our findings indicated that the soils at both reforestation sites and secondary forest were strongly acidic in nature with pH (H2O) of less than (pH < 5.5) with low nutrient status. The acidic nature of the soils might be ascribed to the presence of high exchangeable Al which concomitantly, increased the level of Al saturation of the studied soils. Soil organic matter in secondary forest was significantly higher than that of the reforestation sites which indicate large pool of fresh organic matter and its accumulation at surface soils derived from the above vegetation. Notwithstanding, there were significant differences observed in soil available phosphorus between the sites at both surface and subsurface soils. In terms of soil fertility status, the SFI value in SM96 was higher than all the studied sites at surface soils with 23.76. In contrast, secondary forest depicted a higher value of SEF at surface and subsurface soils with 15.16 and 10.97, respectively. However, no clear significant differences were observed in terms of SEF at surface soils for all the studied sites. Based on the current progress of this study, SFI and SEF can be used as indicators of soil quality for estimating soil fertility status in this study

Growth of Acacia mangium at Different Stand Ages and Soil Physicochemical Properties in Sarawak, Malaysia

The information on soil physicochemical properties is vital for the optimum wood biomass production in forest plantation management. The objective of this study was to determine the topsoil physicochemical properties under different Acacia mangium stand ages and their effect on the growth parameters. Five plots were established randomly within each five different stand ages. In all sample plots, the diameter at breast height (DBH) and the total height of standing trees were measured. Soil samples were collected at a depth of 0 to 20 cm at three random points in each plot, then mixed to get a composite before determining physical and chemical properties. DBH mean and the total height of A. mangium increased as stand age increased. The mean annual volume increment maximised at the 8.5 years old stand with 27.9 m3 ha-1 yr-1. Survival rate and stem density decreased as stand age increased. Principal component analysis (PCA) results showed that the most important soil physical properties were soil organic matter, silt and sand contents, bulk density, and moisture content. For soil chemical parameters, exchangeable magnesium (Mg), cation exchange capacity (CEC), total carbon (TC), total nitrogen (TN), and carbon-to-nitrogen (C/N) ratio were the influential soil variables. Soil pH, available phosphorus (P), and clay content were negatively correlated with the growth development of A. mangium trees. Observations suggest that multiple soil variables are essential for the success of the A. mangium plantation

Tree stand floristic dynamics in secondary forests of different ages in Sarawak, Malaysia

Succession is a series sequential processes of the development of floristic community which involves changes in community structure, species composition and diversity over time. The information on tree stand floristic dynamics of various stages of succession in secondary forests in Malaysia is currently lacking. This study was conducted to determine tree stand structure, floristic composition, and species diversity in various stages of secondary forest development in the study areas. A total of 997, 1,842, and 834 tree stems with diameter at breast height (DBH) of > 5 cm were recorded in one-hectare-plots of 5, 10, and 20 year old secondary forests, respectively. The ten most common species in 5 and 10 year old of secondary forests consisted mostly of light demanding species. In the 20 year old secondary forest, these species did not exist. Macaranga gigantea was the most dominant tree species in the 5 and 10 year old secondary forests in terms of basal area and volume per hectare. The most common species, based on density, basal area, volume, and Importance Value Index (IVi), in the 20 year old secondary forest was Adinandra dumosa. The diversity and richness indices of the 10 year old secondary forest were the highest among all study sites. © 2018, Society for Indonesian Biodiversity. All rights reserved

Growth Performance Of Planted Shorea Macrophylla Under Line Planting Technique

A study on the growth performance and survival rate of planted Shorea macrophylla of different age stands was conducted at Sampadi Forest Reserve, Sarawak. The objectives of this study were to assess the growth performance and survival rate of planted S. macrophylla under reforestation activities that were implemented by Forest Department, Sarawak along with several agencies of Japan as to obtain preliminary data for further improvement of future reforestation activities in Sarawak. In this study, S. macrophylla planted under line planting method was selected. Study plots were established in the reforestation areas (planted with S. macrophylla in the year 1996; SM96, 1997; SM97, 1998; SM98 and 1999; SM99). Diameter at breast height (DBH), total height and survival rate were measured. The findings indicated that the growth performance in terms of survivability and mean annual increment of diameter (MAID) in SM96 were the highest and showed better growth as compared to SM97, SM98 and SM99. On the other hand, the mean annual increment of height (MAIH) in SM97 revealed the greatest height among other plots. The survival rate of S. macrophylla in SM96, SM97, SM98 and SM99 were 89%, 81%, 77% and 51% respectively. Substantial growth performance and high survival rate of S. macrophylla implied that microclimate condition such as competition between planted and existing pioneer species of the study area may have affected the planted S. macrophylla. Notwithstanding, it is recommended that proper silvicultural technique is crucial to manage the existing pioneer tree species towards the success of this reforestation programme

Allometric Equations to Estimate the Aboveground Biomass of Seedling and Sapling Plants in 10 and 20 Years Old of Secondary Forests in Sarawak, Malaysia

The seedlings and saplings plant stage determines the successional stages in the secondary forest establishment process. The estimation on aboveground biomass (AGB) of seedling and sapling plants is needed to describe undergrowth's contribution in the secondary forest. This study's objective was to develop allometric equations for accurate estimation of AGB for seedlings-saplings in 10 and 20 years old of secondary forests. The study was carried out at sites with two stages of the fallow period: lands with a fallow period of 10 and 20 years, respectively, in Sarawak, East Malaysia. The AGB data of all selected seedlings and saplings with the different species within 100 sample quadrates were used to develop allometric equations for seedlings and saplings in each study site. This study developed allometric equations to estimate AGB of seedlings-saplings (diameter at the ground surface of < 5 cm), particularly in 10 and 20 years of fallow ages

Evaluation of Physicochemical Properties of Sandy-Textured Soils under Smallholder Agricultural Land Use Practices in Sarawak, East Malaysia

A study was conducted in the Sabal area, Sarawak, to evaluate the physicochemical properties of sandy-textured soils under smallholder agricultural land uses. Study sites were established under rubber, oil palm, and pepper land uses, in comparison to the adjacent secondary forests. *e sandy-textured soils underlain in all agricultural land uses are of Spodosols, based on USDA Soil Taxonomy. *e soil properties under secondary forests were strongly acidic with poor nutrient contents. Despite higher bulk density in oil palm farmlands, soil properties in rubber and oil palm land uses showed little variation to those in secondary forests. Conversely, soils under pepper land uses were less acidic with higher nutrient contents at the surface layer, especially P. In addition, soils in the pepper land uses were more compact due to human trampling effects from regular farm works at a localized area. Positive correlations were observed between soil total C and soil total N, soil exchangeable K, soil sum of bases, and soil effective CEC, suggesting that soil total C is the determinant of soil fertility under the agricultural land uses. Meanwhile, insufficient K input in oil palm land uses was observed from the partial nutrient balances estimation. In contrast, P and K did not remain in the soils under pepper land use, although the fertilizers application by the farmers was beyond the crop uptake and removal (harvesting). Because of the siliceous sandy nature (low clay contents) of Spodosols, they are poor in nutrient retention capacity. Hence, maintaining ample supply of organic C is crucial to sustain the productivity and fertility of sandy-textured soils, especially when the litterfall layers covering the E horizon were removed for oil palm and pepper cultivation

The diameter increment of selected tree species in a secondary tropical forest in Sarawak, malaysia

The diameter at breast height (DBH) increments of dominant tree species in a secondary forest can determine forest growth in the area. This study was conducted to investigate the DBH increments of the nine dominant tree species in a secondary tropical forest. A total number of 180 trees representing nine species, seven genera, and six families were selected for the assessment of DBH increments during two years of study. Those nine species, namely: Acacia mangium Willd. (2.33 cm year-1), Endospermum diadenum (Miq.) Airy Shaw (1.05 cm year-1), Cratoxylum arborescens Blume. (0.96 cm year-1), Vernonia arborea Buch. Ham. (0.96 cm year-1), and Cratoxylum glaucum Korth. (0.80 cm year-1) had shown a high growth rate during the assessment, while the other four species such as Macaranga gigantea Mull. Arg., Macaranga triloba Mull. Arg., Euodia glabra (Bl.) Bl., and Vitex pubescens Vahl. had 0.53, 0.48, 0.37, and 0.30 cm year-1 in DBH increments, respectively. The average DBH increments for the entire selected species was 0.86 cm year-1 for periodic measurement and 0.75 cm year-1 for monthly measurement. This information is needed in order to understand the succession process in the secondary forests. It is important for the selection of the suitable species in a reforestation and a rehabilitation projects

The Impacts of the Alteration in Agriculture on the Environment and Ecosystem in Sarawak, Malaysia

In Sarawak, Malaysia, while large scale oil palm plantations have been rapidly expanding, shifting cultivation has been altering toward more intensified systems or reducing in its area or activities. Some local farmers prefer planting commercial crops such as rubber, pepper and oil palm rather than their traditional crop of upland rice. Issues relating to the influence of shifting cultivation and oil palm plantation on the environment and ecosystem are still disputable because the discussion is usually based on the stereotypical views lacking ecological evidence. In this keynote report for the 7th International Symposium on Kuroshio Science, several topics are presented related to the impacts of shifting cultivation and oil palm plantations on the environment and ecosystem in Sarawak, Malaysia, based on previous studies. We emphasize that further field research is needed with collaboration between multi-disciplinary international researchers to provide empirical data in order to reach conclusions and resolve the issues