Judul: Studi Habitat dan Perilaku Orang Utan (Pongo pygmaeus abelii) di Bohorok Taman Nasional Gunung Leuser.
Abstrak: Orang-utans are big primates living arboreally and solitarily. Their solitary characteristics, wich was found to be quite different from those of other primate species, have been one of the difficulty factors for discovering them in their dwelling places in forests. This in turn, have resulted in a limited number of orang-utans having systemtically been traced during the course of data. collection. The study was aimedd to explore the habitat, daily activities and population of orang-utans related to habitat condition of Bohorok Nastional Park located in Gunung Leuser, and was carried out in forest areas of Sungai Landak and Sungai Musam, from July 1991 until January 1992. Survey methods employed were both the descriptive and qualitative methods. Observations on habitat conditions have included forest structure, vegetation type and composition, preference of food types and home range. Observations on feeding behavior, movements, restings and defensive behaviour to human disturbances and predators within their home range have also been carried out. Vegetation analysis have been carried out by using multiple plot method, and 144 sample plots have been obtained from five longitudinal stripes in forest areas of Sungai Landak and Sungai Musam. ehowed that the dominant species was materialis) with INP of Vegetation analysis 'damar laut' (Shorea 20.06%, 'kayu minyak' (Dipterocarpus sp.) with INP of 19.5%, 'samak jambu (Ixonanthus icesandra) with INP of 15.60%, and 'kayu merah' (Eugenia sp.) with INP of 13.1%. Tree density was fourd to be relatively low, i.e.. only 216 trees/ha, with species variability index (Shannon Wiener Index) of 3.78 and uniformity index of 0.83. Species variability index was considered relatively high and consisted of various age levels of natural forests. Among the various species related to tree densities, the densities of those which served as principal food sources of orang-utans, have been found to be relatively low. Tree density of Ficus sp. for example, was only 0.90 trees/ha, rambung-rambung' (Vernonea arborea) 1.67 trees/ha, rengas' (Gluata rengas) only 0.69 trees/ha, 'baju barus' (Manglietia glauca) 0.83 trees/ha, 'banitan' (Polyanthia glauca) 0.83 trees/ha.
Keyword: Pongo pymaeus abelii

Judul: Habitat analysis and population estimation of sumatran orangutan (Pongo abeii Lesson 1827 at the Forest of Batang Toru, North Sumatra
Abstrak: The Batang TofU forest located in North, Center and South of Tapanuli, North Sumatra was recently found as one of Sumatran orangutan population habitat. A survey of trees species, nesting behavior and population of Sumatran orangutan was carried out during October 2007 up to January 2008 and aimed to analyze: (1) the forest structure, composition and trees distribution (including feeding and nesting trees); (2) estimated density and popUlation; and (3) the threat factors influenced the survival of Sumatran orangutan in Batang TofU forest. The results of the inventory of trees with diameter at breast height (DBH) 2: 10 cm in 3.84 ha areal sampling showed that 274 species in 56 families, represented by 1,896 individuals with total basal area of 148.9 m2lha and density of 498 treeslha. This forest was richer in tree species than other lowland forests in North Sumatra, Borneo and the Malay Peninsula and was dominated by Sapotaceae trees. The most prominent species were Tristania maingayi, Casuarina sumatrana, Quercus sumatrana and Ganua motleyana in every types of forest and differenced with Batang Gadis National Park which dominated by Dipterocarps. There were 96 feeding trees species in 25 families, represented by 536 individuals with total basal area of 46.7 m2lha. The prominent heights of feeding trees were below 30 m and distributed abundantly in the old moist secondary forests. The most important feeding trees for orangutans (Diospyros sp., Eugenia sp., Nephelium sp., Lithocarpus sp., Ficus sp., Artocarpus sp., Durio sp., and Garcinia sp.) were abundantly found in the old moist secondary forests, too. Orangutans commonly prefer to nest on the top of tree bar and the main branch of trees (DBH 20-30 cm; heights 15-20 m), especially in the middle canopy (20-30 m). Considering that there were enough feeding trees in this canopy. The most preferred nesting trees genus/species were Quercus sp., Syzygium sp., Shorea sp., Diospyros sp. and Lithocarpus sp. It was also invented 267 orangutan nests along 40.125 km cumulative lengths of line transects or equal with 0.54 percent of study area conducted at 11 sites. Densities were found higher in the old moist secondary forest while it was conversely lower density in the mixed forest. The distributions of nests were tended to clumped, related to the distribution of feeding trees. Orangutan population in 748.86 km2 ha potential habitat was approximately 337-421 individuals. Their distribution was limited by elevation and food availability. Human activities such as land conversion for agriculture purposes had become important factors affecting orangutan distribution. Field fact finding showed that many orangutan direct sightings and nests were located much closer to area human activities and logging concessions. This eventually has become real and concreted threat to their remaining population. It's needed to conduct further research in long-term monitoring and develop a strategic planning which promotes community involvement for the conservation of orangutan.
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Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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