Judul: Soil Fauna Diversity in the Agroforestry Areas of Mount Halimun Salak National Park
Abstrak: Taman Nasional Gunung Halimun Salak (TNGHS) merupakan area konservasi yang melibatkan masyarakat dalam pengelolaan lahan dengan sistem agroforestri. Keberadaan fauna tanah di lahan agroforestri diperlukan sebagai indikator kesuburan tanah. Penelitian bertujuan mengidentifikasi keanekaragaman fauna tanah, menganalisis pengaruh kerapatan vegetasi serta hubungan faktor lingkungan terhadap keanekaragaman fauna tanah di lahan agroforestri TNGHS. Metode pengambilan sampel fauna tanah dengan pitfall trap. Analisis data dengan mengukur kelimpahan, indeks keanekaragaman (H’), kekayaan (DMg) dan kemerataan (E) spesies, uji t paired dan korelasi pearson. Hasil penelitian ditemukan 15 ordo dan 32 famili dengan famili Formicidae (Hymenoptera) paling banyak ditemukan. Indeks H’ dan DMg pada kerapatan tinggi lebih besar (0,72 dan 3,28) dibandingkan dengan kerapatan sedang (0,63 dan 2,95). Indeks E pada kedua kerapatan tergolong rendah dan menunjukkan adanya dominansi dari famili Formicidae. Hasil uji t paired menunjukkan tidak ada perbedaan yang signifikan antara kerapatan tinggi dan sedang. Keanekaragaman fauna tanah berkorelasi sangat rendah dengan pH tanah, respirasi, dan intensitas cahaya. Sementara dengan ketebalan serasah korelasinya rendah, dan dengan suhu tanah korelasinya sedang., Gunung Halimun Salak National Park (TNGHS) is a conservation area that involves communities in land management with agroforestry systems. The presence of soil fauna in agroforestry land is needed as an indicator of soil fertility. The study aims to identify the diversity of soil fauna, analyze the effect of vegetation density and the relationship of environmental factors on soil fauna diversity in agroforestry land TNGHS. The method of sampling soil fauna with pitfall traps. Data analysis by measuring the abundance, diversity index (H'), richness (DMg) and evenness (E) of species, paired t test and Pearson correlation. The results of study found 15 orders and 32 families with Formicidae family (Hymenoptera) found the most. The H' and DMg indices at high density were greater (0.72 and 3.28) than those at medium density (0.63 and 2.95). The E index in both densities was low and indicated the dominance of Formicidae family. The paired t test results showed no significant difference between high and medium densities. Soil fauna diversity was very lowly correlated with soil pH, respiration, and light intensity. While with litter thickness the correlation is low, and with soil temperature the correlation is moderate.
Keyword: Agroforestri, Fauna tanah, Keanekaragaman, Taman Nasional Gunung Halimun Salak

Judul: Diversity of Soil Arthropod in the Rehabilitation Zone of Gunung Halimun Salak National Park
Abstrak: Arthropoda tanah merupakan salah satu faktor penentu dari kesuburan tanah dan kehadirannya memiliki peranan penting terhadap ekosistem. Penelitian ini dilaksanakan di Zona Rehabilitasi, Resort Gunung Kendeng, Kawasan Taman Nasional Gunung Halimun Salak (TNGHS). Penelitian bertujuan untuk mengidentifikasi keanekaragaman, menganalisis pengaruh kerapatan vegetasi dan menganalisis pengaruh kondisi lingkungan terhadap keanekaragaman Arthropoda tanah di Zona Rehabilitasi TNGHS. Sampel Arthropoda tanah diambil pada petak pengamatan 50 m x 50 m sebanyak 14 petak pengamatan. Sub petak pengamatan ditempatkan sebanyak 9 kali ulangan secara acak pada tiap petak pengamatan. Pengambilan sampel tanah dan pengukuran faktor lingkungan dilakukan pada sub petak pengamatan berukuran 50 cm x 50 cm sebanyak tiga kali ulangan tiap petak pengamatan. Didapatkan 24 famili Arthropoda tanah yang berasal dari 13 ordo yang berbeda. Indeks keanekaragaman (H’) antara dua kerapatan vegetasi tidak berbeda nyata, pada kerapatan vegetasi tinggi didapatkan H’ 0,80 dan pada kerapatan sedang H’ 0,73. Hubungan keanekaragaman Arthropoda dengan faktor edafis seperti respirasi tanah yaitu berbanding terbalik, sedangkan pH tanah dan ketebalan serasah menunjukkan hubungan yang berbanding lurus. Hubungan faktor klimatis dengan keanekaragaman Arthropoda pada kerapatan vegetasi tinggi adalah berbanding lurus, sedangkan pada kerapatan vegetasi sedang menunjukkan hubungan yang berbanding terbalik., Soil arthropod is one of the determining factors of soil fertility and have an important role in the ecosystem. The research was conducted in the Rehabilitation Zone, Gunung Kendeng Resort, Gunung Halimun Salak National Park (GHSNP). The purpose of this study was to identify the diversity, analyze the effect of vegetation density, and analyze the effect of environmental conditions on soil arthropods in Rehabilitation Zone on GHSNP. Soil arthropod were collected from 50 m x 50 m with a total 14 observation plots. Sub- observation plots were placed 9 repetation in each plot. Soil sampling and environmental factor measurements were taken on 50 cm x 50 cm sub plot with 3 replications. There are 24 families of soil arthropods were obtained from 13 different orders. The index of diversity (H’) between two vegetation densities was not significant, with H’ values 0,80 for hight vegetation density and 0,73 for moderate vegetation density. The relationship between diversity of soil arthropod and edaphic factors such as soil respiration showed an negatively correlation, while pH and soil pH showed a positively correlation. The relationship between climatic factors at high vegetation density showed a linear relation, while at moderate vegetation density showed an inverse relation.
Keyword: soil arthropod, climatic, diversity, edaphic, pitfall trap

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.
Keyword: