Judul: Diversity of AMF Spores Isolation from Dipterocarpaceae Stand (in Area IUPHHK-HA PT Sari Bumi Kusuma West Kalimantan).
Abstrak: FMA (Fungi Mikoriza Arbuskular) dapat bersimbiosis dengan tanaman dari berbagai tipe lokasi, salah satunya dengan lokasi yang ada di PT Sari Bumi Kusuma yang didominasi oleh famili Dipterocarpaceae. Tujuan dari penelitian ini ialah menganalisis keanekaragaman FMA di ekosistem hutan Dipterocarpaceae di areal PT Sari Bumi Kusuma Kalimantan Barat. Sampel tanah diambil dari tiga lokasi yang ada di PT Sari Bumi Kusuma. Isolasi spora dari sampel tanah dilakukan dengan menggunakan metode tuang basah. Spora diidentifikasi dengan melihat reaksi spora setelah ditetesi dengan larutan Melzer. Data sifat fisik dan kimia tanah diperoleh dari PT Sari Bumi Kusuma. Nilai bobot isi, porositas, dan permeabilitas tidak berbeda jauh pada setiap lokasi. Tekstur tanah pada ketiga lokasi ialah lempung liat berpasir pada kedalaman 0–20 cm. Sifat kimia tanah pada ketiga lokasi tidak berbeda jauh. Nilai C-organik, N-total, dan P di lokasi dua memiliki nilai yang lebih tinggi di antara lokasi satu dan tiga. Nilai pH pada ketiga lokasi bersifat masam yaitu berkisar antara 4,76–4,93. Nilai Al pada lokasi dua memiliki nilai yang lebih tinggi dibandingkan dengan lokasi satu dan tiga. Kepadatan spora di lokasi tiga lebih tinggi dibandingkan dengan lokasi satu dan dua. Nilai kepadatan spora FMA tidak dipengaruhi oleh sifat fisik dan kimia tanah. Nilai keragaman spora FMA pada setiap lokasi sama yaitu tiga genus, tetapi macam genus di lokasi satu dan dua berbeda dengan lokasi tiga. Genus Glomus dan Acaulospora ditemukan pada semua lokasi. Genus Gigaspora ditemukan pada lokasi satu dan dua, sedangkan genus Scutellospora hanya ditemukan pada lokasi tiga. Glomus memiliki nilai kelimpahan relatif lebih tinggi dibandingkan dengan tiga genus lainnya, yaitu sebesar 48,43%, sedangkan Gigaspora memiliki nilai terendah, yaitu sebesar 3,13%. Genus Glomus memiliki frekuensi paling besar dengan nilai 79,17%. Hal ini menunjukan bahwa genus Glomus penyebarannya 79,17% dari tiga lokasi yang ada di areal PT Sari Bumi Kusuma. Genus Gigaspora memiliki nilai frekuensi spora yang terendah yaitu sebesar 8,33%, berarti keberadaan penyebarannya hanya 8,33% dari tiga lokasi yang ada di areal PT Sari Bumi Kusuma.
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Judul: Keanekaragaman Cendawan Mikoriza Arbuskula (CMA) di Hutan Pantai Ujung Genteng, Sukabumi-Jawa Barat
Abstrak: Indonesia is one of the countries that has a megadiversity of microorganisms and has a large area of coastal forests. However, research on microbial diversity particularly AMF as one of the dominant microbes in a coastal forest ecosystems has not been done extensively. The main objective of this research was to study the diversity and distribution of AMF in coastal forest and to analyse effects of salinity on the fungal and plant community at Coastal Forest Ujung Genteng Cape, Sukabumi - West Java. This research was carried out in two parts: field, green house and laboratorium experimental activities. Field experimental activities were conducted for vegetation analysis, collecting of plant root system, rhizosphere soils from tree and pole phase,. seedling of understorey plants for fungal colonization analysis, isolation and identification of AMF and soil characteristics, include salinity. Green house and laboratorium activities were carried out for isolation, identification and colonization analysis of AMF. Field research location was divided into three zones, first zone was 0 – 70 m distance from coastal area (P), second zone was 71 – 140 m distance from coastal area (T), and third zone was 141 m distance from coastal until forest up to area in the center (H). Twenty three AMF species from 45 plant rizosphere were identified. The fungi belong to 5 species of Acaulospora, 2 species of Gigaspora, 13 species of Glomus, 1 species of Paraglomus and 2 species of Scutellospora. Glomus geosporum was the most dominant AMF in the ecosystem with the value of frequency was 16.49% - 23.67%. Glomus etunicatum, Acaulospora foveata, A. longula, A. scrobiculata, A. tuberculata, and Scutellospora auriglobosa were the AMF that had frequency higher than other species but less than G. geosporum in the field. Results from vegetation analysis indicated that Ujung Genteng Coastal Forest had 68 plant species belonging to 40 families. Dysoxylum parasiticum and Piper cf. baccatum were dominant plants in the ecosystem. The plant community measured at the three zones experimental sites were differed. The similarity index value of the plant community (Is) between coastal P) and center (T) area was 35.42%, between center (T) and forest center (H) was 32.53%, and between coastal edge (P) and forest center (H) was 27.04%. There was no correlation between diversity of plant and diversity of AMF onserved. Diversity of AMF were influenced with all interaction environment factors especially salinity. Two species of AMF had a narrow distribution and found only in a rhizosphere of one plant species . Glomus sp 5. found only in Guettarda speciosa rhizosphere and Glomus sp6. in Salacia sp. rhizosphere. Nineteen species were identified from P zone, 17 species from T zone and 14 species from H zone, with the index diversity values of AMF were 0.73 – 6.64, 0.85 – 4.93 and 1.26 – 4.84, respectively. The salinity at Ujung Genteng Cape was falled in moderate degree with the value of 420 – 1735 μs/cm. The salinity influenced the diversity of AMF and plant community structures. Nineteen species were identified from P zone, 17 species from T zone and 14 species from H zone,
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Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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