Judul: The Carbon Dynamics in Rewetted Tropical Peat Swamp Forest
Abstrak: Extensive areas of tropical peat swamp forests (PSFs) have been deforested, degraded, and converted to other land uses. In degraded and drained conditions, the carbon emission is greater than the carbon sequestered, making this ecosystem a significant contributor to greenhouse gas (GHG) emissions from forestry and land-use sectors. Rewetting interventions as part of restoration management have been strongly recommended to mitigate the GHG emissions from degraded and drained tropical PSFs. GHG emission reductions or carbon benefits from the rewetting intervention is calculated by subtracting the GHG emissions from rewetted PSFs with GHG emissions from drained PSFs. Due to the lack of site-specific emission factors (EFs) from rewetted tropical PSFs, default EFs derived from Tier 1 methodology proposed by the Intergovernmental Panel on Climate Change (IPCC) have been widely used to quantify carbon benefit from the rewetting intervention in tropical PSFs. However, GHG emissions are not only affected by the climatic zone and soil nutrient status but also by the site-specific characteristics such as vegetation cover, previous land use, and restoration management being implemented. Therefore, the application of default EFs to a specific land cover could under- or over-estimate the carbon benefit, mainly if applied to a specific tropical PSF cover at the national and project levels. To assess this situation, we conducted a study with the intent of contributing to the restoration of tropical PSFs, particularly by providing site-specific GHG EFs for undrained and rewetted sites in tropical PSFs in Central Kalimantan Province, Indonesia. Both sites had been selectively logged prior being restored. The restoration was started in 2016. The study was divided into three phases: the first was a systematic review and meta-analysis of peer-reviewed literature and data, the second was an assessment of the study sites’ biophysical characteristics and carbon stocks, the third evaluated the variability of GHG EFs in the study sites. In the first phase (Chapter two), a review and meta-analysis were conducted to evaluate the effect of rewetting on carbon emissions by comparing the carbon emissions (CO2, CH4, and Dissolved Organic Carbon [DOC]) from rewetted peatlands (treatment sites) with drained peatlands (control sites) in various climatic zones and at different restoration times. Twenty-seven articles passed the inclusion criteria and were used for meta-analysis. Three of these articles were from tropical climates while the remainder were from boreal and, predominantly, temperate climates. The overall effect size indicates that peatland rewetting can reduce the CO2 emission rate by -1.343 ± 0.358 Mg CO2-C ha-1 yr-1, while significantly increasing the CH4 emission rate by 0.033 ± 0.003 Mg CH4-C ha-1 yr-1. However, there was no discernible effect of rewetting on DOC. The findings highlight the lack of primary data from rewetted tropical peatlands which indicates an opportunity to conduct more research on carbon emissions. In the second phase (Chapter three), biophysical characteristics, carbon stock, and fluxes of the study sites were assessed. The biophysical characteristics of both sites were not significantly different, except for the C/N ratio. The number of species per ha and basal areal in the undrained site were 78, and 23.2  3.1m2/ha While in the rewetted
Keyword: Carbon benefit, greenhouse gas, emission factors, meta-analysis, peatland restoration, heterotrophic respiration

Judul: Dinamika Karbon Lahan Gambut yang Dibasahi-ulang Pada Berbagai Tutupan Lahan di Kabupaten Bengkalis, Riau
Abstrak: The deforestation and degradation of tropical peatland swamp forests (PSFs) followed by land conversion and drainage generate greenhouse gas (GHG) emissions. This changes PSFs from carbon sinks to carbon sources, thus contributing to climate change. The rewetting of degraded peatlands is expected to control soil respiration, encourage regrowth, and transform these landscapes back into carbon sinks. In this study, experimental plots were established to measure the effect of peatland rewetting on three different land cover types (a reforested area, an oil palm plantation and a rubber plantation) following the clearing of PSF land in Bengkalis Regency, Riau. Carbon dynamics were assessed by measuring total ecosystem carbon stocks (TECS) and GHG emissions in these experimental plots before and after the rewetting of the landscape. Common tree species in the reforested area (including Ficus sp., Dyera polyphylla, Mezzetia parviflora, Callopyhllum teysmannii, Cratoxylon arborescens, Macaranga sp., Hevea brasiliensis, and Shorea uliginosa) have basal areas of 0.24 ± 0.02 m2 ha-1. Rubber trees in plantations have a basal area of 0.14 ± 0.02 m2 ha-1. The TECS were highest in the reforested area (3,983.08 ± 318.14 Mg C ha-1), followed by the oil palm area (3,523.90 ± 253.9 Mg C ha-1), and finally by the rubber plantation area (3,363.08 ± 207.8 Mg C ha-1). In the reforested area and the oil palm area, the proportion of heterotrophic soil respiration (SRh; 48.91 ± 4.75 and 54.98 ± 1.53 Mg CO2 ha-1 yr-1) to total soil respiration (SRt; 49.68 ± 6.84 and 55.71 ± 5.54 Mg CO2 ha-1 yr-1) was roughly 98% before rewetting. On the other hand, SRh (67.67 ± 2.13 Mg CO2 ha-1 yr-1) was slightly higher than SRt (61.36 ± 7.28 Mg CO2 ha-1 yr-1) in the rubber plantation area. Overall, this shows that peatland rewetting can reduce the CO2 flux in these three land cover types. Mean CH4 flux consistently increased after rewetting in the reforested area (-0.70 ± 0.28 to 0.84 ± 0.28 Mg CH4 ha-1 yr-1), oil palm area (0.37 ± 0.16 to 0.90 ± 0.61 Mg CH4 ha-1 yr-1), and the rubber plantation area (-0.57 ± 0.05 to 1.05 ± 0.37 Mg CH4 ha-1 yr-1). N2O flux in the reforested, oil palm, and rubber plantation areas was 0.12 ± 0.03, 0.15 ± 0.08, and 0.37 ± 0.12 Mg N2O ha-1 yr-1, respectively, and decreased to –0.06 ± 0.02, -0.10 ± 0.05, and 0.19 ± 0.07 Mg N2O ha-1 yr-1, respectively, after rewetting., Deforestasi dan degradasi hutan rawa gambut tropis (PSF) yang diikuti dengan konversi penggunaan lahan dan drainase menghasilkan emisi gas rumah kaca (GRK). PSF sebagai reservoar kaya karbon berubah dari penyerapan menjadi emisi karbon ekosistem yang berkontribusi terhadap perubahan iklim. Pembasahan kembali lahan gambut yang terdegradasi sebagai bagian dari restorasi diharapkan dapat mengendalikan respirasi tanah, mempercepat pertumbuhan vegetasi, dan melindungi bentang alam agar tetap menyimpan karbon. Kami membuat plot percobaan untuk mengukur pengaruh pembasahan gambut di tiga tutupan lahan yang berbeda (kawasan revegetasi, perkebunan kelapa sawit dan karet) setelah konversi di Kabupaten Bengkalis, Riau. Kami menilai dinamika karbon dengan mengukur total stok karbon ekosistem (TECS) dan emisi GRK di tutupan
Keyword: Canal blocking, Carbon stocks, GHG fluxes, Groundwater level, Soil respiration

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
Keyword: