Judul: Struktur dan Komposisi Tegakan Hutan Tanaman  Shorea leprosula Miq. di KHDTK Haurbentes, Bogor
Abstrak: Shorea leprosula Miq. (meranti merah) merupakan salah satu jenis dari famili Dipterocarpaceae. Proses regenerasi S. leprosula dapat diketahui dengan mempelajari struktur dan komposisi jenisnya. Keberadaan jenis ini mengalami penurunan sehingga perlu dilakukan kegiatan konservasi. Penelitian ini bertujuan menganalisis struktur dan komposisi jenis pada areal tegakan S. leprosula dan kondisi permudaannya. Pengambilan data dilakukan di KHDTK Haurbentes pada petak 32b, 35, 82, 83, dan 84 yang didominasi tegakan S. leprosula. Hasil penelitian menunjukkan jumlah pohon terbesar berada pada kisaran diameter pertengahan dengan grafik sebaran diameter cenderung berbentuk lonceng. Stratifikasi tajuk terdiri atas stratum A, stratum B, dan stratum C yang didominasi oleh jenis S. leprosula, S. stenoptera, dan S. pinanga. Berdasarkan hasil identifikasi ditemukan sebanyak 257 individu pohon yang meliputi 9 jenis, dari 4 marga, dan dari 3 famili. Permudaan S. leprosula memiliki jumlah yang banyak dan mendominasi pada semua petak pengamatan., Shorea leprosula Miq. (red meranti) is a species of the family Dipterocarpaceae. The regeneration process of S. leprosula can be known by studying the structure and composition of its type. The existence of this type has decreased so that it is necessary to carry out conservation activities. This study aims to analyze the structure and type composition of the S. leprosula stand area and its youth conditions. Data collection was carried out at KHDTK Haurbentes on plots 32b, 35, 82, 83, and 84 dominated by S. leprosula stands. The results showed that the largest number of trees was in the mid-diameter range with a diameter distribution chart tending to be bell-shaped. The heading stratification consists of stratum A, stratum B, and stratum C which are dominated by the types S. leprosula, S. stenoptera, and S. pinanga. Based on the identification results, 257 individual trees were found, including 9 types, from 4 clans, and from 3 families. S. leprosula youth has a large number and dominates on all observation plots.
Keyword: youth, S. leprosula, structure of stands

Judul: Komposisi Jenis dan Struktur Tegakan Shorea stenoptera Burck di Areal KHDTK Haurbentes, Kabupaten Bogor, Jawa Barat
Abstrak: Luasan hutan di Indonesia yang semakin berkurang akibat deforestasi memerlukan pengelolaan hutan lestari. Shorea stenoptera Burck merupakan salah satu jenis endemik tanaman kehutanan di Borneo. IUCN menyatakan bahwa jenis tersebut termasuk ke dalam status hampir terancam (Near Threatened). Tujuan penelitian ini adalah menganalisis komposisi jenis, struktur tegakan, dan regenerasi alami tegakan S. stenoptera, serta mengidentifikasi pengaruh aspek biofisik terhadap keragaan regenerasi alami S. stenoptera di KHDTK Haurbentes, Kabupaten Bogor, Jawa Barat. Metode yang digunakan adalah analisis vegetasi dengan membangun petak pengamatan sebanyak 5 petak. Hasil penelitian menunjukkan bahwa jenis S. stenoptera mendominasi pada setiap tingkat pertumbuhan pada petak pengamatan S. stenoptera. Struktur tegakan menunjukkan kurva J terbalik. Hal tersebut mengindikasikan tegakan S. stenoptera mengalami perubahan formasi ke hutan alam. Regenerasi S. stenoptera menunjukkan regenerasi normal dengan kerapatan individu semakin berkurang seiring bertambahnya kelas diameter. Aspek biofisik seperti kelerengan dan elevasi sangat memengaruhi pertumbuhan S. stenoptera., The decrease of forest areas in Indonesia because of deforestation need sustainable forest management. Shorea stenoptera Burck is native forest species in Borneo. IUCN declare this species included in Near Threatened. This research aims to analyze species composition, stand structure and natural regeneration of Shorea stenoptera Burck, also identify the biophysics effect on the regeneration performance of S. stenoptera in KHDTK Haurbentes. This research methods is using vegetation analysis by constructing five observation areas. The results thats S. stenoptera dominating in every growth level in S. stenoptera observation area. Stand structure showing inverse J curve. Thats indicates S. stenoptera stand have changed to nature forest. S. stenoptera regeneration showing normal regeneration with density decreased along diameter class increased. Biophysics aspect like slope and elevation effects the S. stenoptera growth.
Keyword: biophysics, natural forest, regeneration

Judul: Sintesis Nanokristal Magnetit Menggunakan Urea sebagai Penjerap Cr(VI)
Abstrak: The study was to synthesize and characterize magnetite nanocrystal. Magnetite powder was synthesized using hydrothermal method from FeSO4 as precursor and sodium hydroxide and urea as the base sources. Characterization of the obtained powder was carried out using X-ray diffraction, scanning electron microscope, and energy dispersive X-ray analyzer. The crystallite size of magnetite by X-ray diffraction was obtained from 18,23 to 67,34 nm. The scanning electron microscope observations showed that magnetite particles underwent agglomeration. Magnetite powder was used as Cr(VI) adsorbent. The results showed that adsorption capacity for urea-based magnetite at pH 1-5 in 2 hours were 1.92; 1.91; 1.59; 1.20; and 1.21 mg/g, respectively. Adsorption capacity for sodium hydroxide-based magnetite (pH 1-5, 2 hours) were 1.74; 1.83; 0.64; 0.69; and 0.77 mg/g. The results indicated that urea-based magnetite is able to increase adsorption capacity.
Keyword: