Judul: Kajian Ekologi Tumbuhan Langka Rotan Beula Ceratolobus glaucescens Blume di Cagar Alam Sukawayana Sukabumi Jawa Barat
Abstrak: Indonesian forest possesses a huge number species of plants. Among those plants, there is a species of rattan, called Rotan Beula (Ceratolobus glaucescen Blume), has been protected by Indonesian Government through Governmental Regulation (Peraturan Pemerintah) No.7/1999 about Preservations of Flora and Fauna Species. Sustainability of Rotan Beula should be kept through various efforts. One of efforts to keep the sustainability of this rattan is conducting the ecological study of Rotan Beula. The aims of this study is to determine the structure, composition, and diversity vegetation which grows at habitat of rotan beula; to know the population condition of rotan beula; and to identify the ecological factors of rotan beula. Sample units were made by using purposive sampling method at every place which is grown by rotan beula. The form of each sample unit is circular plot. The width of circular plot for trees and poles were 0.1 ha, for sapling were 0.01 ha, and for seedlings were 0.001 ha. The data that were collected are biological and physical factors of rotan beula. The processing and analysis of data was done using Minitab's program version 14 . Vegetation structure at the habitat of rotan beula consisted of fledged strata (A=1.18%, B=2.29%, C=8.87%, D=26.67% and E=60.98%). Vegetation composition at habitat of rotan beula was dominated by teureup (Artocarpus elastica) (Importance Value Index [IVI]=26.5%) for tree level, heucit (Baccaurea javanica) (IVI=31.95%) for pole level, patat (Phrynium capitatum) (IVI=28.44%) for sapling level, and Derris trifoliate (IVI=38.95%) for seedling level. The vegetation richness at habitat of rotan was 8.79 for tree level, 7.58 for pole level, 7.12 for sapling level, and 3.77 for seedling level. The variety index for level of tree, pole, sapling, and seedling respectively was 3.43; 3.31; 3.33; and 2.87. Rotan beula is supported by physical factor such as relative humidity of air (71-95%), air temperature (26-320C), optimum pH (6.5-6.8), Ca (4.06-10.67 me/100 g), Mg (2.77-6.14 me/100 g), K (0.72-1.32 me /100 g), Na (0.66-1.3 me/100 g), N (0.09-0.14%), S (2.65-4.24 ppm), P (3.4-5.7 ppm) and litter's depth was 1-2 cm. The condition of rotan beula populations are well, they still grow normally. This conditions was described with young age (446 individuals) is more than the total of Rotan beula in old age (162 individuals). The sustainability of rotan beula’s population at Sukawayana Natural Reserve (SNR) was being threatened by society activity surround the SNR. The density of Rotan beula was affected by density of pole level (n=7; t=7.81; p=0.001) and relative humidity of air (n=7; t=12.10; p=0.000). It can be formulated with regression: rotan beula density = -1155 + 0.154 density of pole + 13.9 relative humidity of air.
Keyword: 

Judul: Keragaan Rotan di Areal Konservasi Ex-Situ Hutan Pendidikan Gunung Walat Sukabumi, Jawa Barat
Abstrak: Ex-situ conservation stands has been established in Gunung Walat University Forest (GWUF) since 2005. However, the performance of rattan has never been evaluated. The objectives of the research were i) to review the correct species name of rattan and ii) to assess the growth variation of rattan with respect to shade trees, environmental factors (light and pest). The growth performance was observed through assessment of species composition and structure of the stand including distribution of diameter and length, biomass estimation and environmental effects (light and pest). The results showed that i) there were 3 (three) rattan species planted in the ex-situ conservation stand, namely Calamus manan, Daemonorops melanochaetes and Daemonorops rubra, ii) The composition and structure of the stands were still dominated by the shade trees. Rattan was found predominantly at strata C (4–20 m) and strata D (1–4 m). The normal distribution was observed only on diameter and length of C.manan and D.melanochaetes, respectively. The highest biomass was observed in D. rubra that was estimated as much as 26.6 tons/ha. The light had significant effect on D.rubra diameter only. On the other hand, pest had no significant effect on rattan growth variables.
Keyword: rattan, growth performance, ex-situ conservation

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
Keyword: