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Semarang is one of many cities which has high vulnerability, damage, and high risk affected by climate change. This study was aimed to determine securing, protecting of Semarang coastal area, especially in Tugu and Genuk Sub-district. Literature review was carried out to seek the proper seawall design and material which feasible to be built in coastal area of Tugu and Genuk Sub-district. Field observation was conducted to determine location characteristic to build seawall in Tugu and Genuk Sub-district. The study revealed that many area of Semarang coast was damage as impact of coastal building, the loss of natural protection as well as effect of global warming. The existing seawall was varied but mostly in damage condition. Therefore it is recommend to build seawall in Karanganyar and Tugurejo Village (in Tugu subdistrict) to support the eco-edutourism in Semarang City as well as ini Trimulyo Village (Genuk Subdistrict) to established sediment enrichment ready for mangroves replant.Keywords : securing, protection, coastal, SemarangSemarang merupakan salah satu kota yang memiliki tingkat kerentanan, bahaya dan resiko tinggi akibat dampak perubahan iklim. Kajian ini bertujuan untuk melakukan kajian pengamanan dan perlindungan pantai di wilayah pesisir Kecamatan Tugu dan Genuk, Kota Semarang. Kajian dilakukan ini melalui review literatur dan observasi lapangan. Kajian literatur dilakukan terhadap desain alat penahan ombak (APO) yang memungkinkan dibangun di wilayah pesisir Kecamatan Genuk dan Tugu serta untuk mendapatkan informasi tentang bahan atau material yang dapat digunakan untuk membangun APO. Observasi lapangan dilakukan untuk mengetahui karakteristik lokasi yang akan dibangun APO dan ketersediaan material sesuai desain yang telah direkomendasikan. Hasil kajian ini menunjukkan bahwa kerusakan pantai yang terjadi di Kota Semarang cukup banyak yang diindikasikan sebagai dampak dari bangunan-bangunan yang menjorok ke laut, hilangnya perlindungan alam pantai dan juga merupakan efek dari pemanasan global. Kondisi APO dan breakwater saat ini sangat beragam, namun pada umumnya sudah rusak sehingga mengurangi fungsinya sebagai alat perlindungan pantai. Untuk itu disarankan dibangunnya alat penahan ombak di Kelurahan Karanganyar dan Tugurejo (Kecamatan Tugu) untuk mendukung program eco-eduwisata Kota Semarang dan Kelurahan Trimulyo (kecamatan Genuk) untuk sediment enrichment yang nantinya lokasi siap ditanami mangrove.Kata kunci : pengamanan, perlindungan, pantai, Semarang

Globally, erosion of muddy tropical coasts that are dominated by aquaculture ponds, is an increasing problem. Restoration of mangrove greenbelts may counteract such erosion, by restoring the sediment balance. Hence, we aim to unravel the processes controlling natural mangrove regeneration in both "landward" (i.e., into aquaculture ponds) and seaward direction, using the fast eroding coastline of Demak (Indonesia) as case study. Firstly, we investigated which physical and chemical factors drive landward mangrove expansion by relating them to the presence/absence of mangrove seedlings in abandoned aquaculture ponds. Secondly, we investigated which physical parameters control seaward mangrove expansion by relating them to expansion and retreat at the seaside of mature mangrove stands.Landward mangrove expansion into abandoned aquaculture ponds was positively related to both emergence time (%) and sediment stability (i.e., shear strength), which are in turn both associated to bed level elevation and pond drainage. Surprisingly, there was no effect of soil chemistry. Seaward expansion of existing mangrove stands was strongly associated to foreshore morphology. Mangroves only expanded in the presence of an elevated mudflat, whereas the absence of a mudflat in combination with a concave (hollow) profile was associated with mangrove retreat. Our findings suggest that restoration of a mangrove greenbelt can be stimulated landward by improving drainage of abandoned aquaculture ponds. This enhances sediment stability and allows ponds to accrete. Seaward expansion can be induced by restoring foreshore morphology. Present results are discussed in the context of large-scale applications.

Ekosistem mangrove merupakan salah satu ekosistem yang berperan dalam mengurangi karbon di udara, dan menyimpan karbon dari udara dalam bentuk biomassa pada bagian tubuh tumbuhan mangrove. Penelitian tentang estimasi cadangan karbon ini sangat diperlukan untuk menunjang perbaikan iklim dunia. Karena saat ini dunia sedang mengalami krisis global yang disebut climate change. Tujuan penelitian ini adalah mengestimasi cadangan karbon yang tersimpan pada tegakan dan substrat mangrove di kawasan mangrove Desa Timbulsloko. Metode yang digunakan yaitu purposive sampling method dan eksploratif, dilakukan di tiga stasiun dengan kondisi ekosistem mangrove yang bervariasi. Setiap stasiun penelitian dibagi menjadi tiga plot penelitian untuk menghitung nilai biomassa tegakan digunakan rumus allometrik untuk mengestimasi cadangan karbon pada tegakan mangrove. Data karbon substrat didapat dari kandungan bahan organik substrat yang dianalisis di Laboratorium. Berdasarkan hasil penelitian, diketahui bahwa cadangan karbon pada tegakan mangrove sebesar 12.370,8 ton/ha, sedangkan estimasi cadangan karbon pada substrat mangrove sebesar 1.307,77 ton/ha. Hasil tersebut menunjukkan bahwa estimasi cadangan karbon pada tegakan mangrove lebih besar dibandingkan dengan estimasi cadangan karbon pada substrat mangrove. Hasil estimasi cadangan karbon pada tegakan mangrove meningkat seiring dengan meningkatnya besarnya biomassa tumbuhan dan kerapatan mangrove. Sedangkan estimasi cadangan karbon pada substrat diduga lebih dipengaruhi oleh bahan organik dan lokasi penelitian. Estimates of Carbon Stok in the Mangrove Area in Timbulsloko Village,Demak, Central Java Mangrove ecosystem is one of the ecosystem that play a role in reducing carbon in the air. One of the functions of mangrove is to store carbon from the air form of biomass in the body parts of mangrove plants. This research on the estimation of carbon stocks is needed to support the improvement of world climate. Today the world is experiencing a global crisis called climate change. The purpose of this research are estimate of carbon stock on stands and substrate in mangrove area of Timbulsloko Village. This research used purposive sampling and explorative method, conducted in three stations with varying mangrove ecosystem conditions. The research was divided into three research plots per station to calculate the stand biomass value using allometric formula in estimating carbon stocks of mangrove area. Substrate carbon data obtained from the content of substrate organic materials analyzed at Laboratorium. Based on the result of research, it is found that carbon stock in mangrove stands is 12.370,8 ton/ha, while estimation of carbon stock on mangrove substrate is 1.307 ton/ha. These results show that estimates of carbon stocks in mangrove stands are greater than estimates of carbon stocks on mangrove substrates. The estimation of carbon stocks on mangrove stands increases with increasing of plant biomass and mangrove density, while estimates of carbon stocks on the substrate are suspected to be more influenced by organic materials and research sites.

Abstract. Setyadi G, Pribadi R, Wijayanti DP, Sugianto DN. 2021. Mangrove diversity and community structure of Mimika District, Papua, Indonesia. Biodiversitas 22: 3562-3571. Despite being one the largest mangrove forest in the world, there are few studies on mangrove diversity and community structure in Mimika, Papua Province. The study collected data from 4 estuaries of Mimika Region, i.e. Kamora, Tipuka, Ajkwa and Minajerwi. Mangrove species, tree diameter at breast height and canopy height data were collected in 10 m x 10 m plot with three replicates for distance, specifically 0, 250, and 500m perpendicular to the riverbank. This study found 66 mangroves species consisting of 20 major, 10 minor, and 36 associate mangrove species. Their density ranged from 577-1,345 trees ha-1 with diversity Shannon-Weiner diversity indices (H’) ranging from 0.62-1.19 and Evenness Index (J’) ranging from 0.09-0.18. The canopy height of the mangrove trees was ranged from 9-42.5 m. The highest density species was Rhizophora apiculata (333 ha-1) followed by Avicennia marina, Bruguiera gymnorrhiza, and Camptostemon schultzii, while B. parviflora, S. alba, and X. granatum were the least dominant. Regarding basal area, R. apiculata and B. gymnorrhiza were the highest with medians of 7,853 cm2 ha-1 and 5,201 cm2 ha-1 respectively. In the low tidal zone area, mangrove was dominated by A. marina, Sonneratia alba and R. mucronata. Medium low to medium high tidal zones were dominated by B. gymnorrhiza, R. apiculata, and B. parviflora. The high tidal zone was more dominated by Nypa fruticans.