Judul: Estimation of Carbon Stock on Burned Peatlands in Kepulauan Meranti Regency, Riau Province
Abstrak: Kebakaran gambut termasuk penyumbang emisi gas rumah kaca (GRK) terbesar di Indonesia, terutama di Kepulauan Meranti. Penelitian ini bertujuan menduga simpanan karbon dari biomassa di atas permukaan tanah (AGB) dan menganalisis pengaruh kebakaran terhadap simpanan karbon pada lahan gambut di Kepulauan Meranti. Penilaian area bekas terbakar menggunakan indeks Normalized Burn Ratio (NBR) dan nilai difference Normalized Burn Ratio (dNBR). AGB diperkirakan dengan pendekatan diameter dari model alometrik, kemudian dikonversi menjadi fraksi karbon dengan nilai 0,47. Pengaruh keparahan kebakaran, keterulangan kebakaran, dan periode terakhir kebakaran terhadap simpanan karbon dianalisis dengan regresi linier berganda. Simpanan karbon dari AGB pada lahan gambut bekas terbakar 2014 sebesar 27,41 ton ha-1, terbakar berulang 2018–2019 sebesar 10,11 ton ha-1, dan terbakar 2020 sebesar 0,58 ton ha-1. Keparahan kebakaran, keterulangan kebakaran, dan periode terakhir kebakaran secara bersamaan berpengaruh signifikan terhadap simpanan karbon pada lahan gambut bekas terbakar. Demikian juga pengaruh masing-masing variabel prediktor yang signifikan terhadap variabel respons, tetapi dengan taraf sigifikansi yang berbeda., Peat fires are among the largest contributors to greenhouse gases (GHGs) emissions in Indonesia, especially in Kepulauan Meranti. This study aims to estimate carbon stocks from aboveground biomass (AGB) and analyze the effect of fires on carbon stocks on peatlands in Kepulauan Meranti. The assessment of burned areas uses the Normalized Burn Ratio (NBR) index and the difference Normalized Burn Ratio (dNBR) value. AGB estimated with a diameter approach from an allometric model, then converted into a carbon fraction with a value of 0.47. The effect of burn severity, fire repeatability, and the last period of fire on carbon stocks was analyzed by multiple linear regression. Carbon stocks from AGB on peatlands burned in 2014 amounted to 27.41 tons ha-1, repeated burns in 2018–2019 amounted to 10.11 tons ha-1, and burned in 2020 amounted to 0.58 tons ha-1. Burn severity, fire repeatability, and the last period of fire simultaneously have a significant effect on carbon stocks on burned peatlands. Likewise, the effect of each predictor variable is significant on the response variable, but with a different level of significance.
Keyword: biomass, carbon, fire, Normalized Burn Ratio, peatlands

Judul: Analysis of Vegetation and Drought Conditions in Peatland following 2015’s Fires in Kepulauan Meranti
Abstrak: Lahan gambut di Indonesia banyak yang mengalami degradasi menjadi lahan tidak produktif. Kerusakan lahan gambut berdampak pada penurunan kualitas ekosistem gambut, penurunan keanekaragaman hayati, peningkatan risiko kebakaran, serta peningkatan emisi gas rumah kaca ke atmosfer. Tujuan dari penelitian ini untuk menganalisis kondisi vegetasi dan kekeringan pada lahan gambut pasca kebakaran hutan dan lahan tahun 2015. Penelitian mengambil kasus kebakaran di Pulau Padang, Kepulauan Meranti, Riau. Penelitian menggunakan data citra satelit Landsat-8 surface reflectance (SR) untuk menentukan indeks vegetasi dan kekeringan yaitu: Normalized Burn Ratio (NBR), Normalized Difference Vegetation Index (NDVI), dan Normalized Multi-band Drought Index (NMDI). Hasil penelitian menunjukkan bahwa NBR merekam wilayah dengan tingkat kebakaran yang tinggi di tahun 2014, 2015, dan 2020. Hal tersebut didukung dengan sebaran vegetasi secara spasial yang ditunjukkan oleh citra NDVI. Nilai rata-rata NDVI yang rendah menunjukkan sebagian besar wilayah kajian merupakan lahan minim vegetasi . Sebagian besar area citra NMDI di lahan kosong menunjukkan kondisi kering dan sangat kering dengan nilai NMDI setiap tahun (2014-2020) yang tinggi. Tahun pre-fire 2019 memiliki cakupan area tertinggi untuk kondisi lahan sangat kering. Meski demikian, laju pertumbuhan vegetasi menunjukkan tren peningkatan setelah periode kebakaran., Most peatlands in Indonesia are degrading into unproductive land. Damage to peatlands decreases the quality of the peat ecosystem, decreasing biodiversity, increasing the risk of fire, and increasing greenhouse gas emissions into the atmosphere. This study aims to analyze the condition of vegetation and drought on peatlands after the 2015 fire in Padang Island, Meranti Islands, Riau. The method was processed by performing Landsat 8 surface reflectance (SR) image data to determine: Normalized Burn Ratio (NBR), Normalized Difference Vegetation Index (NDVI), and Normalized Multi-band Drought Index (NMDI). The results of this study indicate that NBR recorded areas with high fire rates in 2014, 2015, and 2020. Validate by the spatial distribution of vegetation shown by NDVI images. The low average NDVI value indicates that most of the study area is land with minimal vegetation. Most of the NMDI image areas in vacant land show a dry and extreme dry condition with high NMDI values every year (2014-2020). The pre-fire year 2019 had the highest area coverage for extreme dry land conditions. However, the vegetation growth rate showed an increase after the fire period.
Keyword: burn severity, hotspot, plants water content, soil moisture, spatial index

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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