Judul: Habitat suitability and waterbirds distribution in Percut Sei Tuan, North Sumatra
Abstrak: Percut Sei Tuan is an important bird habitat in Sumatera. Not only important habitat for resident waterbirds, this area is a stop-over area for migratory waterbirds every year. This study aimed at analyzing the importance of Percut Sei Tuan as waterbird habitats, including its macrozoobenthic food source, and examining its habitat suitability for waterbirds. The study was conducted from September 2010 to March 2011. Concentration count and block method were used to assess the number and species of waterbirds in four sites, namely Bagan Percut, Tanjung Rejo, Pematang Lalang and Pantai Labu. Samples of macrozoobenthos (n = 10 plots) were taken using sweep nets and core samplers. A spatial analysis using ArcGis 9.3 was used to identify habitat suitability. Waterbirds and macrozoobenthic communities were calculated with Shannon, evenness and similarity indences. Similarity among communities were showed with a dendrogram. Stepwise regression was used to analyze physical and chemical factor. A total of 190,375 individuals of 50 waterbird species were recorded. Percut Sei Tuan have waterbirds diversity index of 2.20. Species diversity at four sites varied among 1.69 and 2.84. Wading birds were dominant in Tanjung Rejo while shorebirds were dominant at three sites. The highest diversity was found in Pematang Lalang while the lowest was found in Tanjung Rejo. Waterbirds were classified into four groups based on guild, i.e. wading birds, shorebirds, waterfowls and seabirds. Based on migratory habit, waterbirds were classified into three groups i.e. resident, migrant and unkown. The research revealed that there were 26 macrozoobenthos species in Percut Sei Tuan. Diversity index of macrozoobenthos was 2.68, diversity was varied among sites, the highest was at Bagan Percut 3 (2.26) and the lowest was at Bagan Percut 2 (0.71). Similarity index was 0.82. Sediment depth and texture were affected macrozoobenthic abundance and diversity. Bivalves were the highest abundance group of species in the community. This research found only five of 10 land cover used to feeding ground by waterbirds i.e. mud flat, rice field, fish pond, forest marsh and shrub. Waterbirds used mudflat at Bagan Pecut, Pematang Lalang and Pantai Labu for feeding ground. The analysis to physical and chemical factor (i.e. macrozoobenthic, height sediment, water depth, pH, BOD, and salinity) showed significant effect up to 60% for waterbirds presence. Feeding ground selected by waterbirds depend on food availability, habitat availability and degree of disturbance. Human distrubance had a high impact on the population and distribution of endangered Mycteria cinerea and Leptoptilos javanicus. Habitat suitability of wading birds and shorebirds was generally found in the same place, namely mudflat, rice fields and fishponds. However, the feeding ground of both bird guilds was different.
Keyword: Habitat Suitability, Percut Sei Tuan, Sumatera Utara, Macrozoobenthos

Judul: Bird Community in Three Different Habitat Types in Muara Gembong and Their Contributing Factors
Abstrak: Rawa air asin dan mangrove merupakan salah satu habitat yang terancam di Indonesia, karena pembangunan dan konversi besar-besaran di daerah pesisir. Muara Gembong merupakan salah satu lahan basah pesisir yang tersisa di Jawa dan menjadi salah satu suaka bagi burung-burung rawa dan mangrove. Meskipun sudah banyak penelitian tentang komunitas burung di lahan basah, masih sedikit penelitian komunitas burung di lahan basah Indonesia. Komunitas burung diobservasi di 31 plot di tiga tipe habitat. Sebanyak sebelas variabel biotik dan abiotik juga diukur dalam penelitian ini untuk menentukan faktor yang paling memengaruhi komunitas burung, yaitu jumlah jenis tumbuhan (pohon, semak, herba, dan keseluruhan), persentase tutupan pohon, semak, dan herba, nilai pH air, kekeruhan air, kedalaman air, serta kadar garam pada air. Metode point count digunakan dalam penelitian ini untuk mengamati komunitas burung. Data komunitas burung kemudian dianalisis dengan analisis keanekaragaman, analisis kemerataan, dan estimasi kelimpahan. Faktor-faktor habitat dianalisis dengan redundancy analysis dan principal component analysis (PCA) untuk menganalisis faktor-faktor yang memengaruhi komunitas burung. Komunitas burung di Muara Gembong merupakan campuran dari jenis-jenis burung spesialis dan generalis. Komunitas burung paling beragam dapat dijumpai di habitat mangrove (H’ = 3,306). Mangrove (42 jenis) juga menjadi habitat dengan jumlah jenis burung terbanyak, diikuti oleh habitat rawa berumput (39 jenis) dan tambak ikan (34 jenis). Berdasarkan estimasi kelimpahan, diperkirakan terdapat 55 jenis burung di habitat mangrove, 39 jenis di rawa berumput dan 42 jenis di tambak ikan. Berdasarkan analisis guild, burung yang paling banyak dijumpai merupakan burung insektivora, diikuti dengan burung omnivora dan piscivora. Jumlah jenis tumbuhan (pohon, semak, tumbuhan bawah, dan keseluruhan) menjadi faktor yang paling memengaruhi komunitas burung. Jumlah total tumbuhan juga menjadi vektor terpanjang yang dapat menjelaskan keanekaragaman jenis burung paling signifikan. Analisis PCA terpisah pada tiap tipe habitat menunjukkan faktor abiotik lain dapat berpengaruh dengan keanekaragaman burung. Komposisi jenis tumbuhan mangrove (43,33% variasi) menjadi komponen paling berpengaruh di habitat mangrove. Karakteristik vegetasi rawa berumput (36,67% variasi) dan faktor-faktor abiotik lain (18,6% variasi) menjadi komponen paling berpengaruh di habitat rawa berumput. Tumbuhan air di tambak ikan (34,27% variasi) dan tutupan area bersemak (20,45% variasi) menjadi komponen paling berpengaruh di habitat tambak ikan. Hal ini menunjukkan bahwa komunitas burung di lahan basah masih sangat bergantung pada vegetasi sebagai tempat mencari makan dan beristirahat., Marshlands and backswamps are among threatened habitat in Indonesia along with mangroves, particularly in Java due to area development and land conversion. Muara Gembong is one of the remaining wetlands in Java and serve as one of the last refuges for bird community in wetlands, particularly mangrove and marsh-associated bird. Although there are plenty of bird community study in terrestrial wetlands, there are still less studies about wetland bird community conducted in Indonesia. The bird community were observed in 31 plots in three habitats. There are also eleven habitat variables collected in three habitats, i.e. mangrove, marsh, and fishpond, to see which variable affects bird abundance and diversity most. The variables are the number of plant species (trees, shrubs, herbs, and overall), cover percentage (trees, shrubs, and herbs), water pH, water turbidity, water salinity, and water body depth. The bird community were observed with
Keyword: vegetation, mangrove, marshland, bird community analysis

Judul: Konstruksi aritmetika kurva eliptik F(2m) supersingular dan non-supersingular untuk skema kunci publik ElGamal
Abstrak: Algoritme ElGamal adalah salah satu algoritme kunci publik dengan aritmetik modular p yang mempunyai struktur grip siklik Z(p). Tingkat keanaman algoritme ini terletak pada pemecahan masalah logaritme diskret dari Z(p). Akan tetapi, tingkat keamanan tadi tahun ke tahun semakin menurun yang disebabkan kemampuan pemecahan algoritme diskret semakin meningkat. Untuk memenuhi tingkat keamanan yang memadai dibutuhkan p yang cukup besar yang menyebabkan proses enkripsi dan dekripsi menjadi lambat.
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