Judul: Survivorship and Growth Rate of Rasamala (Altingia excelsa Noronha), Puspa (Schima wallichii (DC.) Korth.) and Jamuju (Dacrycarpus imbricatus (Blume) de Laub.) on Degraded Land in the Upstream of Cisadane Watershed
Abstrak: Changes in land use often threaten biodiversity. A slow primary succession can, however, be accelerated by conducting a restoration program. The aims of this study were to i) obtain data of survivorship and growth rate and ii) assess the influences of environmental factors on the growth of Rasamala (Altingia excelsa), Puspa (Schima wallichii), and Jamuju (Dacrycarpus imbricatus) on a degraded land in the upstream of Cisadane watershed. Observations were carried out two times: 6 and 12 months after planting. Survivorship percentages at different slopes were obtained by dividing the amount of living species during the period of the observation with the total amount of plants planted at the beginning of the observation. A PCA biplot analysis was used to assess the interaction between biotic and abiotic factors influencing the survivorship. Growth rate was done by measuring the height, diameter, and canopy spread of individual plants. Assessments of biotic and abiotic environment that influence the growth rates were also conducted. The results showed that the survivorship percentages of Rasamala, Puspa, and Jamuju were 87,18%, 82,05%, and 77,14%, respectively. On the 40° slopes, the survivorship of Rasamala was 93,75%, while those of Puspa and Jamuju were 84,61% and 66,67% respectively. On the 60% slopes, the survivorship was 82,25% for Rasamala, 81,81% and 64,70% for Puspa and Jamuju respectively. Higher growth rate was found in Jamuju, followed by Puspa and Rasamala. Environmental factors (both biotic and abiotic) significantly influenced the three species survivorship. Plant height, diameter and canopy area had significant correlations with plant growth rates.
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Judul: Pertumbuhan anakan Avicennia marina dan Rhizophora mucronata pada jarak tanam yang berbeda dengan menggunakan teknik penanaman guludan
Abstrak: Ecological impacts due to the destruction of mangrove ecosystem are the loss of various flora and fauna, which in the long run will disrupt the balance of mangrove ecosystem as well as coastal ecosystem. Therefore, rehabilitation efforts are urgently needed to maintain the overall functions of mangrove forest. In the last several years, there is a technique called guludan, which is developed to rehabilitate mangrove forest (Kusmana et al. 2005a). In applying guludan technique, a study had been conducted using seedlings of A. marina and R. mucronata with different spacings, i.e. 0.25 x 0.25 m, 0.5 x 0.5 m, and 1 x 1 m. There has been not many studies conducted yet to develop growth models and increments for the planted seedlings using guludan technique. It is important to obtain information on the growth models and increments in regards to the success of guludan technique. This study is aimed at: 1) formulating models and increments for diameter and height growths for A. marina and R. mucronata seedlings at different spacings, 2) determining the most ideal spacing which can result to the greatest growth and increment for trunk diameter and height of A. marina and R. mucronata seedlings. Data collections were conducted from October 2008 through October 2011 (3 years) at the Mangrove Arboretum Angke Kapuk, located at the side of Sedyatmo Toll, KM 22 through KM 23, Jakarta Province (06o06’45” LS and 106o43’54” BT). This location has water depth of 2-3 m with salinity of 28-30 ppt and pH of 6.88 – 7.52 (Kusmana 2010). Variables observed were trunk diameter and height of A. marina and R. mucronata seedlings with different spacing until reaching 36 months old of age. The starting age for A. marina was 3 months old, whereas for R. mucronata was 6 months old. The trunk diameter was measured at 10 cm above land surface using caliper. The trunk height was measured starting from where the diameter measurement was taken, up to the growth using measurement tape. The observations were conducted every 4 months during the 3 years of study. The models used were non linear regression models developed with software R, using non linear regression analysis. Models used were logistic, Gompertz and Richards. Models for height growth used were power, exponential, polynomial and invers polynomial. The best model was determined using criteria as follows: 1) the model has p value < 0.05; 2) the model has the least AIC, BIC, and RMSE; 3) the model has the greatest R2 and R2adj; 4) the model has residual value which are randomly scattered and homoscedastic. After the best model was chosen, then the mathematical equations were developed to predict the Mean Annual Increment (MAI) and the Current Annual Increment (CAI). MAI is the average of diameter growth model or height growth model over time (f(y)/t). CAI is the differential of diameter growth model or height growth model (dy/dt). Based on the study, it is observed that the diameter growth and height growth of A. marina as well as diameter growth of R. mucronata followed logistic 2 equation. On the other
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Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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