Judul: Komposisi Vegetasi dan Keanekaragaman Tumbuhan Obat di Arboretum PT Arara Abadi Provinsi Riau
Abstrak: One of potency natural resources in PT. Arara Abadi’s Arboretum is medicinal plants. A study on vegetation composition and diversity of medicinal plants in the area of PT. Arara Abadi’s Arboretum was conducted during October-November 2009. The data that were collected during the study consisted of primary and secondary data. The primary data consisted of medicinal plants species that were collected through vegetation analysis. The secondary data were general condition of study location consisted of wide and geographically location, climate, hydrological data, flora and fauna. The vegetation analysis used combination of strip and quadrate sampling techniques. The sampling plots were (20 x 50) of meter square width that consisted of 4 strips. The sampling plot was allocated systematically at every 100 m far from each strip. Line is again divided into (20 x 20) of meter plots for trees, (10 x 10) of meter for the pole, (5 x 5) of meter for the stake, and (2 x 2) for seedlings. The result of the vegetation composition in PT. Arara Abadi’s arboretum consisted of 102 species from 47 families. Based on Important Value Index (IVI) the tree level was dominated by Meranti (Shorea smithiana) (48.06 %), the sapling level was dominated by Meranti (Shorea smithiana) (41.43%), the pole level was dominated by Medang (Litsea odoreifera) (34.68%), the seedling level was dominated by Kelat (Syzygium) (20.60%). The biodiversity of plants species that have potency as medicinal plants were 38 species from 25 families, those were 37% from the total plants species found in PT. Arara Abadi’s Arboretum.
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Judul: Keanekaragaman Tumbuhan Berguna di Taman Hutan Raya KGPAA Mangkunagoro I Jawa Tengah
Abstrak: The Grand Forest Park of KGPAA Mangkunagoro I (TAHURA KGPAA Mangkunagoro I) is an area located in Central Java. This area conserves plant diversity which is potential to be utilized. Research on diversity of useful plants was done because the information about it was not yet available. This research aims to identify the diversity of useful plants at KGPAA Mangkunagoro I Grand Forest Park. The research was conducted by method of vegetation analysis and study of literature. The result of this study shows that 51 species (80,95%) from 63 species was identified as useful plants. Medicinal plant is the group of plants that has the highest number, which is 30 species from 24 families. The most widely used parts of plant were wood (23 species) and leaves (22 species).
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Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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