Judul: Analysis of Soil Physical and Chemical Properties and Their Relationship with the Abundance of Soil Mesofauna and Macrofauna in Mount Gede Pangrango National Park
Abstrak: Kelimpahan fauna tanah dipengaruhi oleh berbagai faktor lingkungan meliputi faktor edafis, klimatis, dan keberadaan vegetasi di atasnya. Penelitian ini bertujuan menganalisis kelimpahan fauna tanah pada ketinggian tempat berbeda serta menganalisis pengaruh lingkungan terhadap kelimpahan fauna tanah. Penelitian dilaksanakan pada tiga ketinggian yang berbeda yaitu 1.550 m dpl, 1.650 m dpl, 1.750 m dpl, serta di lahan terbuka (1.200 m dpl). Hasil uji BNT menunjukkan kelimpahan fauna tanah yang berbeda nyata antara ketinggian 1.650 m dpl dengan lahan terbuka, sementara kelimpahan fauna tanah pada ketinggian 1.550 m dpl dan 1.750 m dpl tidak berbeda nyata pada selang kepercayaan 95%. Tutupan vegetasi turut memberikan kontribusi dalam kelimpahan fauna tanah dan dibuktikan dengan lahan terbuka yang memiliki kelimpahan fauna tanah terkecil. Hasil analisis korelasi menunjukkan bahwa intensitas cahaya dan suhu udara berkorelasi negatif, sedangkan kelembaban udara berkorelasi positif dengan kelimpahan fauna tanah. Faktor yang berkorelasi kuat dengan kelimpahan adalah berat basah serasah dan pH tanah., The abundance of soil fauna is influenced by various environmental factors including edaphic factors, climatic factors, and the presence of overlying vegetation. This study aims to analyze the abundance of soil fauna at different altitudes and analyze the influence of the environment on the abundance of soil fauna. The research was conducted at three different altitudes, namely 1.550 m asl, 1.650 m asl, 1.750 m asl, and in open land (1.200 m asl). The LSD test results showed that the abundance of soil fauna was significantly different between the altitude of 1,650 m asl and open land, while the abundance of soil fauna at an altitude of 1,550 m asl and 1,750 m asl was not significantly different at the 95% confidence interval. Vegetation cover also contributes to the abundance of soil fauna as evidenced by open land having the smallest abundance of soil fauna. The results of the correlation analysis show that light intensity and air temperature are negatively correlated, while air humidity is positively correlated with the abundance of soil fauna. Factors that are strongly correlated with abundance are litter wet weight and soil pH.
Keyword: altitude, climatic, diversity, edaphic, vegetation

Judul: Abundance of Soil Macrofauna on Several Land Covers in Balangan Regency, South Kalimantan Province
Abstrak: Keberadaan makrofauna tanah memiliki peran penting dalam mempertahankan dan mengembalikan kesuburan tanah. Penelitian ini bertujuan menganalisis kelimpahan makrofauna tanah dan pengaruh jenis vegetasi, serta lingkungan terhadap kelimpahan makrofauna tanah pada beberapa tutupan lahan di Kabupaten Balangan, Kalimantan Selatan. Pembuatan petak dengan ukuran 20 m × 20 m secara purposive sampling. Analisis data dilakukan dengan uji Beda Nyata Terkecil (BNT) dan uji korelasi Pearson. Kelimpahan makrofauna tanah secara keseluruhan terdiri atas 15 ordo dan 27 famili dengan total individu sebanyak 370 individu/m². Hasil uji BNT menunjukkan kelimpahan makrofauna tanah berbeda nyata di hutan sekunder dan lahan kosong, sedangkan kelimpahan makrofauna tanah tidak berbeda nyata antara hutan meranti dan kebun karet. Berdasarkan uji korelasi Pearson, faktor klimatis kelembapan tanah memiliki hubungan positif yang sangat kuat terhadap kelimpahan makrofauna tanah, serta faktor edafis seperti porositas, C-organik, respirasi, berat basah, berat kering, dan kadar air juga memiliki hubungan positif yang sangat kuat terhadap kelimpahan makrofauna tanah., The existence of soil macrofauna has an important role in maintaining and restoring soil fertility. This study aimed to analyze the abundance of soil macrofauna and the influence of vegetation type, as well as the environment on the abundance of soil macrofauna in several land covers in Balangan Regency, South Kalimantan. Plots measuring 20 m × 20 m were made using purposive sampling. Data analysis used the Least Significant Difference (LSD) test and Pearson correlation test. The overall abundance of soil macrofauna consists of 15 orders and 27 families with a total of 370 individuals/m². The BNT test results showed that the abundance of soil macrofauna was significantly different in secondary forests and empty land, while the abundance of soil macrofauna was not significantly different between meranti forests and rubber plantations. Based on the Pearson correlation test, the climatic factor of soil moisture has a very strong positive relationship with the abundance of soil macrofauna, and edaphic factors such as porosity, C-organic, respiration, wet weight, dry weight, and moisture content also have a very strong positive relationship with the abundance of soil macrofauna.
Keyword: climatic, edaphic, formicidae, secondary forest, vegetation

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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