Judul: Keanekaragaman, Struktur Populasi dan Pola Sebaran Syzygium di Gunung Baung Jawa Timur
Abstrak: The research of Syzygium diversity, its population structure and the distribution patterns were conducted in Gunung Baung Nature Park, East Java. A total of five block locations, each comprising five transect sections, were purposively selected to obtain data of the taxon diversity, population stucture and distribution patterns. The importance value index, the individual number of each stratum (stage class) (i.e. seedlings, saplings, poles and trees) and variance-to-mean ratio were calculated. The principal component analysis, cluster analysis, multiple linear regressions and canonical correspondence analysis were performed to determine the relationships between abiotic and biotic factors in regard with the presence of Syzygium. There were six species of Syzygium in Gunung Baung, Pasuruan, namely S. cumini, S. polyanthum, S. littorale, S. pycnanthum, S. racemosum, and S. samarangense. The population structure of Syzygium varied considerably, only S. pycnanthum and S. racemosum had an ideal structure. This was presumably due to some problems faced by the genus in the process of regeneration, especially during the seedling phase. The distribution patterns of the Syzygium members were generally grouped prefering fertile sites on the slopes. Altitude and the number of bamboo clumps became the determinant (influencing) variables affecting significantly the existence of Syzygium in this mount.
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Judul: Komposisi Jenis dan Struktur Tegakan Hutan di Cagar Alam Sibolangit, Sumatera Utara
Abstrak: Forest is an ecosystem that combines the interaction between biotic and abiotic factors. Ecologically, the formation of forest community formed gradually through the changing of the vegetation and habitat. Community of forest is a dynamic and always changing until it reaches a optimum stage. The growth of a tree species in a forest community is influenced by several factors, including climatic factors, edaphic, physiological and biotic factors. The changing in the factors mentioned previously will take effect on the vegetation structure and composition. Forest with a variety functions and benefits provide a tremendous influence both directly and indirectly to several aspects such as ecology, economic, and social. Utilization of forests can be well manage and reach the sustainably if the information about the forest condition are available. Sibolangit Nature Reserve which is located in Deli Serdang regency. The existence of the Sibolangit Nature Reserve with high biodiversity information still limited, therefore it is necessary needed to have a study of nature reserve in order to explore the benefits and potency of the nature reserve without disturbing the presence and preservation of the forest. Hence, we need a study to in the Nature Reserve Sibolangit of the forest, analyze species the composition, and structure. This research conducted from December 2008 until January 2009 using vegetation analysis techniques with the transeet methods. As preliminary, the transeet divided into plots of 20m x 20m to inventory the trees, 10m x 10m to analyze the pole, 5m x 5m to inventory the saplings, and the 2m x 2m to inventory the seedling. For the sampling unit it uses a sampling design in the form of systematic sampling with random start. Based on the results of observation, the seedlings and saplings dominated by Sono keling (Dalbergia latifolia). While for the poles and trees dominated by Angsana (Pterocarpus indicus). The diversity value in Sibolangit Nature Reserve classified as medium diversity. In Sibolangit Nature Reserve, the highest Similarity Index values was found in the north-south slope and the lowest one found in north-eastern slopes. Forest vegetation Sibolangit Nature Reserve in vertical point of view consists of three strata, namely the stratum A (tree height over 30 meters), stratum B (tree 20-30 meters high), and stratum C (tree height 4- 20 meters), where most of the tree population is distributed in the canopy stratum from 11 until 20 meters. All individuals in the forest show clustered distributed at both the tree and forest regeneration level.
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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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