Judul: Effectiveness of mangrove rehabilitation on pramuka island, seribu archipelago.
Abstrak: Mangrove ecosystem damage is generally caused by human activities, although it is undeniable, nature also has a considerable role. The damage will cause a reduction or even disappearance of system functions and benefits of mangrove for the community and the surrounding environment. To restore the damaged mangrove, it is necessary to attempt rehabilitation through mangrove management on Pramuka Island, Seribu Archipelago. The purpose of this study was (1) to examine the factors that determine the success of the rehabilitation of mangrove ecosystems on Pramuka Island, Seribu Archipelago, (2) to assess the effectiveness of the rehabilitation of mangrove ecosystems and the factors supporting the success and failure on Pamuka Island, Seribu Archipelago, and (3) to arrange the recommendations to improve the effectiveness of the rehabilitation of mangrove ecosystems on Pramuka Island, Seribu Archipelago. Assessment of mangrove rehabilitation success rate on Pramuka Island was done by analyzing several indicators of using an effectiveness index with taking into account also the environmental parameters of water quality such as temperature, flow velocity, salinity, pH, DO, TSS, nitrate, potassium, BOD5. Indicators of effectiveness of mangrove include eco-biologi indicators of mangrove rehabilitation that includes survival, growth and percent cover; and social indicators that include public participation and public perception. Results of this study showed that the majority of mangroves on Pramuka Island are the saplings, while for trees and seedlings only a small fraction. All existing mangrove rehabilitation was the result of the different planting years, only two trees ware considered a pre-existing natural mangrove long ago. Based on the measurement results, mangrove rehabilitation on Pramuka Island had a relative cover between 0.03 to 2.82%; growth of 13.33 to 32.50 cm/yr; and survival rate of 3.02 to 67.36%. Environmental conditions in the area of rehabilitation of mangrove waters are shallow water reef around the island stretches to a distance of about 500 m from the shoreline and the water quality is suitable for mangroves. Values of water quality measurements include temperature from 31.7 to 35 °C; flow velocity 0.1-0.3 m/s; TSS 4-16 mg/l; pH 7.54 to 8.20; salinity 25-28 psu; DO from 7.6 to 9.4 mg/l; nitrate from 0.039 to 0.156 mg/l; orthophosphate 0.002 to 0.283 mg/l; potassium 0.272 to 0.698; and BOD5 from 2.00 to 4.60 mg/l. Based on social conditions, all the people (100%) know about mangroves, both the function and existence. 60% of people also know that the mangrove on Pramuka Island is managed by TNKpS. In addition, people also take a role and participate in themanagement of the mangrove. Approximately 80% of respondents said had been involved in management efforts, including by contributing to maintain, not destroy the existence of mangroves and mangrove occasional cleaning of garbage. Community involvement is in line with the perceived benefits. 80% of vii respondents said that the mangroves are considered to lessen the blow of the waves, erosion and add coolness on the beach. Community involvement in management efforts can be improved if people know and can take advantage of direct utilization of mangrove like to candied fruit, wood utilization, etc.. So far there is no direct use
Keyword: mangrove ecosystem, TNKpS, ehabilitation, effectiveness

Judul: Karakteristik dan Dampak Pengelolaan Ekosistem Mangrove Rehabilitasi di Kawasan Konservasi dan Wisata: Studi Kasus Pulau Pramuka dan Pulau Pari
Abstrak: Ekosistem mangrove memiliki manfaat ekologi maupun ekonomi. Namun, rentan terhadap kerusakan dan penurunan biodiversitas. Oleh sebab itu, pemahaman mengenai pengelolaan dan strategi rehabilitasi mangrove penting. Penelitian ini bertujuan menganalisis karakteristik pengelolaan ekosistem mangrove di kawasan konservasi dan wisata di Pulau Pramuka dan Pulau Pari, Kepulauan Seribu, pada November 2023–Februari 2024. Metode yang digunakan, yaitu melakukan wawancara secara purposive sampling, pengambilan data vegetasi mangrove, dan sampel makrozoobentos. Variabel yang dianalisis meliputi karakteristik pengelolaan (tata kelola, aturan lokal, strategi rehabilitasi, dan pengelolaan pasca tanam) dan dampak pengelolaan (cakupan mangrove rehabilitasi, kerapatan mangrove, dan keanekaragaman makrozoobentos). Hasil penelitian menunjukkan dua jenis mangrove di Pulau Pramuka (Rhizophora stylosa dan Rhizophora mucronata) dan empat jenis mangrove di Pulau Pari (Rhizophora stylosa, Rhizophora apiculata, Soneratia alba, dan Bruguiera cylinndrica). Tingkat kerapatan mangrove pada kedua pulau tergolong sangat padat (31.714-128.500 ind/ha). Kepadatan makrozoobentos di Pulau Pramuka dan Pulau Pari masing-masing sebesar 121 ind/m2 dan 189 ind/m2 dengan keanekaragaman sedang. Kerapatan mangrove berkorelasi positif dengan kepadatan makrozoobentos (r>0.9). Terdapat perbedaan pengelolaan mangrove di kedua pulau dari segi tata kelola, aturan lokal, pengawasan dan pemeliharaan pasca tanam., The mangrove ecosystem has both ecological and economic benefits. However, it is vulnerable to damage and biodiversity loss. Therefore, understanding mangrove management and rehabilitation strategies is crucial. This research aims to analyze the characteristics of mangrove ecosystem management in conservation and tourism areas on Pramuka Island and Pari Island, Kepulauan Seribu, from November 2023 to February 2024. The methods used include purposive sampling interviews, mangrove vegetation data collection, and macrozoobenthos sampling. The variables analyzed include management characteristics (governance, local regulations, rehabilitation strategies, and post-planting management) and management impact (rehabilitated mangrove coverage, mangrove density, and macrozoobenthos diversity). The research results show two types of mangroves on Pramuka Island (Rhizophora stylosa and Rhizophora mucronata) and four types on Pari Island (Rhizophora stylosa, Rhizophora apiculata, Soneratia alba, and Bruguiera cylindrica). The mangrove density on both islands is classified as very dense (31,714-128,500 ind/ha). The macrozoobenthos density on Pramuka Island and Pari Island is 121 ind/m2 and 189 ind/m2, respectively, with moderate diversity. Mangrove density positively correlates with macrozoobenthos density (r>0.9). There are differences in mangrove management between the two islands in terms of governance, local regulations, post-planting monitoring, and maintenance.
Keyword: mangroves, macrozoobenthos, management, rehabilitation

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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