Judul: Keterkaitan Sifat Tanah Gambut Terhadap Konsentrasi Hara dan Keragaman Mikrob Serta Makrofauna Tanah di Areal Penanaman Sagu
Abstrak: Indonesia has the largest peat land among tropical countries, about 21 million ha are scattered mainly in Sumatra, Kalimantan and Papua. Spread of peatlands in Indonesia's main islands, only about 6 million hectares are used for agriculture viable. It is associated with the utilization of peat which had many obstacles especially in peatlands that have not experienced further weathering. The one of the natural resources are not optimally managed sago palm (Metroxylon spp). Sago as one of the plants native to Indonesia which is a commodity that has a very good development prospects for the future, in addition to the sago plant has the ability to grow in marginal lands. One of the inputs required by the land associated with land productivity on farm land is soil organic matter and nutrients are available in a number of balanced. Soil microorganisms and organism play an important role in accelerating the supply of nutrients and also as a source of soil organic matter. Among groups of soil microbes, bacteria and fungi are the most likely group to attention. The role of bacteria in the recycling of nutrients such as carbon, nitrogen and phosphorus are very important. The purpose of this study was to examine the relationship between peat soil characteristics associated with plant nutrients and microbial diversity and macrofauna in a sago plantation. The area is used as a plot observations is to consider the different types of land management, the land cover types in the area of community cultivation, sago plantations in the area PT.NSP and sago plantations in the area of PT. NSP on fire. Based on the research results revealed that the highest nutrient content of K is in sago plantations in the area of PT. NSP on fire > community cultivation > sago plantations in the area PT.NSP, while the highest calcium content contained in sago plantations in the area PT.NSP > community cultivation > is in sago plantations in the area of PT. NSP on fire. Relationship between the availability of potassium in the soil with the availability of potassium in leaves and rachis showing a positive relationship between the availability of potassium in the soil with potassium content in the rachis. While the availability of calcium and magnesium in the soil did not show a positive relationship. In this research shown that the physical condition of the environment, that is water table depth pf peat and C/N ratio contribute impact on microbial diversity and macrofauna. The highest microbial and macrofauna diversities was found in community sago cultivation area with peat water table depth of 63.33 cm and content of C/N ratio of 56.12%.
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Judul: Vegetation Diversity and Biomass of Certain Types of Peatland Use In Kepulauan Meranti Regency, Riau. Under academic
Abstrak: The purpose of this study was to assess the diversity of vegetation and biomass on the three different peat land use types; natural forests, gardens, and industrial forest plantation of sago areas (HTI sago). The results showed that the composition of plant species for three growth rates, saplings, pole, and trees stages, ware different among three different peat land use types. The dominant species in natural forests were Shorea parvifolia, Shorea uliginosa, Baccaurea bracteata and Palaquium rostratum. In gardens, the dominant species are Metroxylon spp., Artocarpus sp., Palaquium ridleyi, and Alstonia spatulata Blume.; while in HTI sago areas, including Metroxylon spp, the presence of other species of forest vegetation were Ficus microcarpa, Combretocarpus rotundatus, Baccaurea bracteata and Palaquium rostratum. The higher diversity index of three different growth rates; saplings (2.75), pole (2.99) and trees (3.15) respectively, were only found in the natural forest. On the contrary, the lower diversity index of sapling stage (1.95) was in gardens and both the pole (0.77) and tree (0.44) were belonged to the HTI sago. Potential biomass of pole stages figured out the higher and the lower value were 359,01 ton ha-1 in HTI sago, 159,75 ton ha-1 in gardens and 67,79 ton ha-1 in natural forest, respectively. This trend also occurred nearly equal to the higher stages of trees and a lower value were 209.20 ton ha-1 in HTI sago, but the natural forest 161.13 ton ha-1 higher than the gardens, 107.22 ton ha-1, respectively.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular