Judul: A Study of Carbon Emission from the Digging and Burning of Topogen Peat Soil in Humbang Hasundutan Regency North Sumatra Province
Abstrak: This research aimed to get carbon emission and to count the carbon potential on and under the surface of topogen peat soil area in Humbang Hasundutan, North Sumatera. The research was conducted in two stages: (1) to count the carbon potential (above ground and below ground), which involved the counting of weight volume (bulk density), C content, peat soil thickness and the size of peat soil area, and (2) to count the carbon emission. The below ground biomass was covering 1,43 until 3,71 tons/ha. The biggest carbon reserve was in nonvegetation soil which reached 0,.400 tons, while the smallest carbon reserve was in vegetation soil which reached 0,333 tons. The average of below ground carbon reserve in peat soil areas in Humbang Hasundutan regency was 0,180 tons. The CO2 emission in peat soil areas in Humbang Hasundutan regency could be predicted that 7,9 tons would be emitted out of 2,07 ha of peat soil areas in Humbang Hasundutan regency for 5 years, with a burning efficiency of 25%.
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Judul: Dinamika Karbon Tanah Akibat Konversi Lahan dan Hubungannya dengan Penambahan Gas Rumah Kaca di Atmosfer (Studi Kasus : Pulau Sumatera)
Abstrak: Soil is the largest carbon storage in terrestrial ecosystems, thus soil plays an important role in the global carbon cycle. The increasing of human needs in terms of economic, social, and institutional are the factors affecting land use change in order to meet the necessities of life. Changes of vegetation / land cover / land use causes changes in biomass and biomass carbon stock. This conditions affecting amount and distribution of plant’s scrabs and tissue underneath which are the main source of soil organic material, thus will affect the soil organic carbon stock. Overall, if the organic soil material changing, the organic carbon will change as well. Changes in land cover can increase carbon loss through several mechanisms, namely: 1) destroy soil aggregates that protect the soil organic materials from decomposition, 2) stimulate microbial’s activity by improving soil aeration, 3) mixing the fresh organic material into soil which the conditions are more favourable for decomposition rather than in the soil surface. In addition, cultivate land more easily eroded, resulting in the loss of carbon. Moreover, land use can cause soil more easily being eroded. This research is aimed to estimate soil carbon emissions due to land use changes that occurred since 2003 to 2006 on mineral soil and peat soil on first soil layer in Sumatra island using the method of soil carbon emissions estimation created by the IPCC in 2006. The amount of emissions that occur due to land use change in mineral soil is 38.435.198 acres, which its emissions is 83.025 tons/year of C or equal to 304.704 ton/year of CO2. While the changes that occur in peatlands in Sumatra to contribute as much 41.236.091 tons/year of C or equal to 151.336.454 tons/year of CO2 for 6.643.778 acres of land area change.
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Judul: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix