Judul: The Cliff Revegetation by Clamber Method on The Land After Coal Mining of PT Mandiri Intiperkasa Nunukan of East Kalimantan .
Abstrak: Penambangan batubara maupun mineral dapat memberikan dampak negatif terhadap lingkungan sekitar. Dampak-dampak yang timbul dari operasi penambangan antara lain adalah lahan-lahan menjadi tandus dan tidak produktif. Tingkat erosivitas yang terjadi sangat tinggi karena lahan bekas penambangan telah menghilangkan vegetasi yang tumbuh di atasnya. Tumbuhan sukar tumbuh pada areal bekas penambangan karena kandungan hara sangat rendah dan tanah berpotensi racun terhadap tumbuhan. Revegetasi merupakan usaha untuk memperbaiki dan memulihkan vegetasi yang rusak melalui kegiatan penanaman dan pemeliharaan pada lahan pasca penambangan. Upaya revegetasi yang diterapkan penting untuk menggunakan metode yang tepat dan efisien. Penggunaan tanaman merambat sebagai tanaman perintis dan penutup tebing merupakan upaya awal untuk melakukan revegetasi tebing pasca penambangan. Penelitian ini bertujuan untuk mendapatkan jenis tanaman merambat dan ukuran kerangka penjalar yang tepat untuk revegetasi tebing pada lahan bekas tambang. Berdasarkan hasil penelitian ketiga tanaman merambat yang diujicobakan yaitu Waluh (Cucurbita moschata), Cipir (Psopocarpus tetragonolobus) dan Koro (Canavalia gladiata) merupakan jenis yang tahan terhadap lahan kritis bekas penambangan batubara. Cipir merupakan jenis yang tumbuh paling baik, dengan pertumbuhan panjang batang primer, jumlah daun dan pertumbuhan jumlah cabang yang paling baik. Penggunaan kerangka penjalar dengan 2 ukuran (petak 50 dan 30 cm) tidak berpengaruh nyata terhadap pertumbuhan tanaman.
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Judul: Evaluasi Keberhasilan Tanaman Hasil Revegetasi di Lahan Pasca Tambang Batubara Site Lati PT Berau Coal Kalimantan Timur
Abstrak: Mining activities in the forest areas is done through the lend use of forest areas. The activities of mining must always be followed by reclamation and revegetation to restore the condition of damaged forest area as a result of mining efforts and forest areas can serve again in line with aimed. Revegetation is an effort to repair and restore the damaged vegetation by planting and maintenance activities on the grounds of forest areas former use. Evaluation needs to be done to find out the status of successful revegetation has been done by mining company. Purposes of this research are to assess the successful status of revegetation on post-mining land based on survival rate and plants performance of Acacia mangium on Block Q3 East Elevation 60 Lati Site of PT Berau Coal East Kalimantan. Observation also held to find out the causes of ineffective growth by result of soil analysis on post-mining land, and also to give recommendations of revegetation improvements. The result showed that the success of revegetation status on Block Q3 East Elevation 60 Lati Site is not successful based on survival rate and performance of planted plants. It is caused by the average values of growth and health plant percentage which lower than 80%. The average value of growth percentage is 79,31% and health plant percentage is 71,62%. The main factor of this condition is failure characteristics of soil revegetation which unsupport properly for the growth of plants. The level of soil acidity which appertain very acid soil can cause some important problems and it can be harmful to plants. Soil amendment and replanting vegetation should be done to improve revegetation on Block Q3 East Elevation 60 Lati Site PT Berau Coal East Kalimantan.
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Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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