Judul: Distribution dan population density of silvery langur (Trachypithecus cristatus) in a mangrove forest, Handil Baru Village, East Kalimantan
Abstrak: Lutung kelabu (Trachypithecus cristatus) merupakan salah satu primata dalam famili Cercopithecidae yang tersebar di Kalimantan dan Sumatera. Lutung kelabu menempati daerah pesisir mangrove dan tepi pantai. Saat ini, lutung kelabu di Kalimantan nyaris kehilangan habitat dikarenakan adanya perubahan fungsi lahan. Kelurahan Handil Baru memiliki area mangrove seluas 64 ha yang ditempati oleh lutung kelabu. Informasi mengenai keberadaan lutung kelabu pada kawasan mangrove masih sangat sedikit dibandingkan dengan jenis habitat lainnya sehingga penting untuk dilakukan penelitian. Penelitian ini bertujuan untuk mendeteksi persebaran, mengestimasi kepadatan populasi, dan mendeteksi penggunaan strata pohon serta mengidentifikasi jenis pakan lutung kelabu. Penelitian dilakukan pada bulan Mei-Agustus 2019. Kepadatan populasi dihitung melalui pengamatan langsung dengan metode Concentration Count sedangkan distribusi lutung dianalisis menggunakan software ArcGIS ver 10.4. Pengamatan dengan menggunakan strata pohon dibagi menjadi 4 yaitu tajuk atas, tajuk tengah, tajuk bawah dan terestrial. Metode pengamatan dengan scan sampling dengan interval 5 menit, adapun aktivitas yang dicatat meliputi perilaku harian seperti makan, istirahat, berpindah tempat, bersembunyi dan aktivitas sosial. Pengambilan data jenis tumbuhan pakan lutung kelabu dengan mengamati secara langsung. Pengumpulan data spesies pakan dengan pengamatan secara langsung. Spesies pakan yang tidak teridentifikasi di lapangan selanjutnya akan dikoleksi dengan membuat herbarium. Identifikasi spesimen yang dikoleksi dilakukan di Laboratorium Sistematika Tumbuhan FMIPA Universitas Mulawarman. Pada penelitian ini ditemukan tiga kelompok lutung kelabu pada kawasan mangrove Kelurahan Handil Baru yang tersebar di Handil Baru Muara, Sungai Raden dan Sungai Mantri. Kepadatan populasi di Handil Baru Muara sebesar 6,63 individu/ha, Sungai Raden 2,65 individu/ha dan Sungai Mantri 0,72 individu/ha. Jumlah individu setiap kelompok bervariasi yaitu Handil Baru Muara 24 individu, Sungai Raden 17 individu dan Sungai Mantri 18 individu. Lutung kelabu lebih banyak menggunakan tajuk tengah dan tajuk bawah dalam aktivitasnya. Kelompok lutung kelabu di Handil Baru Muara memiliki jumlah pakan 22 spesies, di Sungai Raden tujuh spesies dan di Sungai Mantri enam spesies. Kepadatan populasi dipengaruhi oleh fungsi lahan, jumlah individu pada lokasi tersebut serta ketersediaan pakan., Silvery lutung (Trachypithecus cristatus) is one of primate a species in the family of Cercopithecidae which distributed in Kalimantan and Sumatra. It inhabit in coastal areas, mangrove and riparian. Currently, silvery lutung in Kalimantan experienced in habitat loss due to land conversion. Handil Baru Sub District has a mangrove area of 64ha, which inhabit by silvery lutung. Information about silvery lutung in mangrove area is still limited than at other habitat type, therefore there is a needed to conduct observation. This study aims is to detect distribution, estimate population density, and use of tree strata and identify the species as food source of silvery lutung. Observations were held during May-August 2019. The population density was determined using Concentration count, through direct observation and the distribution of this species was analyzed using ArcGIS software version 10.4. Observations of tree strata were divided into 4; upper canopy, middle canopy, lower canopy and terrestrial. Observation method was scan sampling at intervals of 5 minutes, recorded activities include daily activities such as eating, resting, moving around, hiding and social activities. Collecting data on the type of food by observing directly. Unidentified plants were collected by making herbarium. The
Keyword: Hitung konsentrasi, sebaran, pakan, kepadatan populasi, lutung kelabu, Concentration count, distribution, food, population density, silvery lutung

Judul: Analysis of habitat types of tricolour langur (Presbytis  chrysomelas ssp. cruciger, Thomas 1892) in Danau Sentarum National Park, Analysis of habitat types of tricolour langur (Presbytis  chrysomelas ssp. cruciger, Thomas 1892) in Danau Sentarum National Park
Abstrak: Lutung sentarum merupakan primata endemik Kalimantan yang saat ini berada pada status Critically Endangered (kritis) berdasarkan daftar merah IUCN dan belum dilindungi undang-undang. Penelitian ini bertujuan menganalisis tipe habitat lutung sentarum di kawasan Bukit Semujan dan mengkaji kelimpahan tumbuhan sumber pakan yang merupakan salah satu unsur daya dukung habitat. Hasil penelitian menunjukkan bahwa habitat lutung sentarum di kawasan Bukit Semujan terkategorikan ke dalam tiga tipe hutan, yaitu hutan rawa; peralihan; dan bukit. Terdapat 83 spesies dari 40 famili tumbuhan menyusun kawasan Bukit Semujan. Hutan rawa didominasi famili Myrtaceae, hutan peralihan didominasi Cluciaceae, dan hutan bukit didominasi oleh famili Dipterocarpaceae. Secara struktur, vegetasi penyusun habitat lutung memiliki permudaan yang melimpah sehingga menjadi indikasi bahwa habitat lutung mampu beregenerasi. Selain itu, sebanyak 16 jenis tumbuhan penyedia pakan lutung sentarum tersebar di seluruh tipe habitat dan dimungkinkan dijangkau oleh lutung karena kondisi tajuk antar habitat yang saling interkoneksi. Kata kunci: endemik, hutan rawa, IUCN, regenerasi, Tricolour langur is an endemic primate of Borneo which is currently in Critically Endangered based on the IUCN red list and not protected by government’s law. Aim of this research is to analyze the habitat type in the Bukit Semujan and assess the abundance of vegetation that provides food, which is one element of the carrying capacity of the habitat. The results showed that the tricolour langur habitat in the Bukit Semujan area was categorized into three types of forest based on topographic and edaphic differences, namely swamp forest; transition; and hills. There are 83 specieses from 40 plant families that make up the Bukit Semujan area. The swamp forest is dominated by the Myrtaceae, the transitional forest is dominated by the Cluciaceae, and the hill forest is dominated by the Dipterocarpaceae family. Structurally, the vegetation that makes up the lutung habitat has abundant regeneration so that it is an indication that the lutung habitat is able to regenerate. In addition, as many as 16 specieses of plants that provide food for tricolour lutung are spread across all types of habitats and it is possible for langurs to reach them due to the interconnection of canopy conditions between habitats. Keywords: endemic, IUCN, regeneration, swamp forest
Keyword: endemik, hutan rawa, IUCN, regenerasi

Judul: Penggunaan Metode Homotopi untuk Menyelesaikan Masalah Nilai Eigen pada Suatu Model Getaran
Abstrak: Most mathematical models of natural phenomena are nonlinear model. One of the nonlinear problems is a problem of vibration which can be considered as an eigen value problem. Here, the nonlinear factor appeared due to the external forces applied to the system. The vibration problem in this study, was solved using the homotopy method. The homotopy method is analytical approach in the nonlinear problems within the series form. The terms of the series were obtained based on a recursive formula in a high deformation. A convergent solution of the series dependent on both the homotopy parameter and the coefficient of nonlinear factors appeared in the model.
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