Variasi Umur Tanaman Reklamasi Terhadap Struktur dan Komposisi Vegetasi di Areal Reklamasi Tambang PT Kideco Jaya Agung, Paser, Kalimantan Timur

Salah satu indikator yang digunakan untuk mengukur keberhasilan kegiatan reklamasi adalah dengan cara menghitung jumlah jenis vegetasi yang tumbuh pada areal reklamasi tersebut. Penelitian ini bertujuan untuk mengkaji variasi umur tanaman terhadap struktur dan komposisi vegetasi di areal reklamasi tambang (KRPT) PT Kideco Jaya Agung (PT KJA), Paser, Kalimantan Timur melalui kegiatan monitoring dan evaluasi vegetasi tahunan. Lokasi studi mencakup 13 (tiga belas) KRPT dengan umur tanaman 1-13 tahun. Nilai kerapatan vegetasi tertinggi pada masing-masing kategori adalah 1.125 individu/ha (KRPT umur 12 tahun) untuk tingkat pohon, 650 individu/ha (KRPT umur 10 tahun) untuk tingkat pancang dan 525 individu/ha (KRPT umur 8 tahun) untuk tingkat semai. Hasil penelitian ini juga menunjukkan bahwa terdapat 51 jenis vegetasi yang berasal dari 22 famili tanaman ditemukan pada areal konsesi PT KJA site Roto Samurangau. Dimana 32 diantaranya merupakan jenis tanaman yang tumbuh secara alami, sedangkan 19 jenis vegetasi lainnya merupakan jenis tanaman pokok. Berdasarkan variasi nilai kuantitatif pada masing-masing lokasi yang diamati, tidak tampak bahwa semakin tua umur tanaman, maka semakin tinggi pula nilai kerapatan vegetasi, basal area, dan kehadiran jenisnya. Namun, meskipun secara umum menurun, keragaman jenis pohon pada tanaman reklamasi yang lebih tua cenderung lebih beragam. Hal tersebut dikarenakan berbedanya situasi dan kondisi masing-masing KRPT yang diamati, seperti perbedaan kondisi tanah, jenis tanaman, dan jarak lokasi studi dengan hutan alam. Berdasarkan hasil identifikasi dan inventarisasi yang dilakukan pada penelitian ini diketahui bahwa KRPT dengan umur tanam 12 tahun memiliki komposisi vegetasi yang paling beragam, dimana dari 19 jenis vegetasi, 14 diantaranya merupakan jenis tanaman yang tumbuh secara alami. ABSTRACTThe one indicator used to measure the reclamation succession activities is by calculating the number of vegetation species that grow in reclamation area. This study aimed to determined the variations in plant age on the vegetation structure and composition in the mine reclamation area (KRPT) of PT Kideco Jaya Agung (PT KJA), Paser, East Kalimantan through annual vegetation monitoring and evaluation activities. The study sites cover 13 (thirteen) KRPTs with a plant age of 1-13 years. The highest vegetation density values in each category were 1,125 individuals/ha (12 years old KRPT) for the tree level, 650 individuals/ha (10 years old KRPT) for the sapling level and 525 individuals/ha (8 years old KRPT) for the seedling level. Present study also showed that there were 51 species of vegetation from 22 plant families found in the concession area of PT KJA, 32 are naturally species while others 19 species are main vegetation. Based on the variation of quantitative values at each location observed, it was not appeared that the older plant age affected to the higher value of vegetation density, basal area, and species presence. However, although it was generally declined, tree species diversity in older reclaimed plants tended to be more diverse. This is probably due to the different situations and conditions of each observed KRPT, such as differences in soil conditions, plant species, and the distance between study site and natural forest. The result of plant species identification and inventory showed that KRPT with a planting age of 12 years had the most diverse vegetation composition, where from 19 species there are 14 species of them grown naturally

Land reclamation pattern and environmental regulation guidelines for port clusters in the Bohai Sea, China

Coastal land reclamation (CLR), particularly port reclamation, is a common approach to alleviating land shortages. However, the spatial extent, percentages, and processes of these newly reclaimed ports are largely unknown. The Bohai Sea is the most concentrated area of port reclamation worldwide. Thus, this study addresses the changes in the different coastline types and port reclamation process in the area. The reclamation area of the 13 ports in the Bohai Sea in 2002–2018 was 2,300 km2, which decreased the area of the sea by 3%. The natural coastline length in Tianjin decreased by 47.5 km, whereas the artificial coastline length increased by 46.6 km. Based on the port boundary, however, only 26.3% of the reclaimed areas have been used for port construction, which concentrates in the Tianjin and Tangshan ports. The ratio of built-up area within the ports is only 32.5%, and approximately 48.3% of the reclaimed areas have no construction projects. The port land reclamation in the Bohai Sea has been undergoing periods of acceleration, peak, deceleration, and stagnation since 2002. Hence, future port reclamation should not be totally prohibited, and fine management should be conducted based on the optimization of the reclaimed port area. The innovation of this research is its analysis of the port internal land use pattern, the percentage of built-up area in the ports, and the sustainability of port reclamation policies. The findings have vital implications for scientifically regulating the spatial pattern and exploring the utility of port reclamation.

Amplification of 16S rRNA primer on rhizosphere bacteria from reclamation area and natural forest of PT. Vale

Open-pit mining activities cause land degradation; therefore, post-mining land recovery or reclamation is essential. An indicator to rate the success of mine reclamation activities is the diversity of soil microbial populations. Molecular bacteria identification requires prior information about the amplification of universal primers for molecular analysis. This study analyzes the amplification of 16S rRNA primers on rhizosphere bacteria isolates from reclamation and forest areas. The research activities encompassed sample preparation, isolation of bacteria isolates, isolation of DNA isolate, quantitative test, qualitative test, and amplification. The findings showed that pure isolates of rhizosphere bacteria from reclamation and natural forest areas that could be used were five and ten isolates, respectively. One isolate (20%) from the reclamation area and four isolates (40%) from natural forest generated DNA band, which were amplified using 16S rRNA.

Health assessment of vegetation composition in the reclamation area of PT Natarang Mining, Tanggamus Regency, Lampung Province

Reclamation is a recovery activity in mining areas, one of which is revegetation. The success of revegetation plants can be seen from the health of the composition and structure of the vegetation when the trees are six years old and over. This study aims to determine the health of the vegetation composition (location, type, and level of tree damage) in the reclamation area of PT Natarang Mining, Tanggamus Regency, Lampung Province. The location of this research is in the area around the main office of PT Natarang Mining, Way Linggo Forest, Bandar Negeri Semuong, Tanggamus Regency, covering an area of 2.97 Ha. The research was conducted through vegetation analysis using the circular plot method and assessing the health of the vegetation composition based on the damage index at the plot level. The results showed that tree vegetation obtained 12 species. The most common tree species found was Falcataria moluccana (Sengon) which amounted to 22 individuals. The most significant contribution of tree species indicated by the highest importance value index was Falcataria moluccana. The location of most damage found in most of the plots was at the bottom of the stem (code 3) and the bottom and top of the stem (code 4). Types of open wound damage (code 03) and gall rust (code 26) were the most dominant causes of damage, with an average damage rate of 35% and 22%, respectively. The health value of the vegetation composition has a value range of 1.20 – 2.00. The average health value of the vegetation composition is 1.50, which is included in the medium category.

Identification of Reclamation Area in Ancol of North Jakarta Using Resistivity Method

The coastal reclamation area is an expansion of coastal areas through technical engineering to develop new land areas. Identification of the reclamation area can be performed by detecting subsurface imaging using the resistivity method. This study used a multi-electrode (multichannel) resistivity imaging method. The resistivity imaging results show a good response of subsurface resistivity and successfully identified reclamation area with low resistivity <27.8 Ωm in almost the study area. Its depth varies from 4 meters to 30 meters. The reclamation results are composed of loose rock that has not been fully compacted, so it has not been well consolidated. As a result, it will experience land subsidence if overload.

Influence of understorey diversity on wildlife at the coal mining reclamation area in South Kalimantan, Indonesia

Nugroho Y, Supandi, Suyanto, Matatula J, Wirabuana PYAP. 2021. Influence of understorey diversity on wildlife at the coal mining reclamation area in South Kalimantan, Indonesia. Biodiversitas 22: 3736-3743. The existence of understorey at the coal mining reclamation area provides an important contribution to improve the environmental quality, especially the wildlife presence. Therefore, this study aims to determine the influence of understorey diversity on the wildlife at the coal mining reclamation area managed by the PT Borneo Indobara, South Kalimantan. This study used an ecological survey conducted in three reclamation areas classified based on the dominant species supporting the process, namely Paraserianthes falcataria (L-1), Anthocephalus cadamba (L-2), and a mixture of both species (L-3). The data were collected in two observation periods, namely August 2019 and August 2020. The results showed that at the first observation, ten families of understorey were observed from the survey and the highest diversity was recorded in L-2 (H'=1.71), followed by L-1 (H'=1.54), and L-3 (H'=1.27). Meanwhile, the wildlife in the first periods was only 6 species consisting of 3 birds, 2 reptiles, and 1 mammal. The number of species from every site was relatively equal at the first observation. In the second observation, the diversity of understorey considerably increased with approximately 22 families from the inventory. The highest understorey diversity in this observation was recorded in L-1 (H'=3.30), L-2 (H'=3.05), and L-3 (H'=3.04). Also, the higher understorey diversity was followed by the higher wildlife with 29 species, which consists of 26 birds, 2 reptiles, and 1 mammal. The highest appearance of bird species was in the L-1 with approximately 19 species, while the number of birds in L-2 and L-3 was relatively similar with approximately 15 species. Based on these results, the understorey diversity significantly contributes to improving the wildlife diversity at the coal mining reclamation area, primarily from the bird species.

Research on Dynamic Stability Optimization of Rock Spreader considering Prevention of Geological Subsidence and Local Collapse in Reclamation Area

The uneven stacking of waste rock materials caused by the dynamic instability of rock spreaders cannot be ignored for geological subsidence and local collapse in reclamation areas. Based on the dynamic stability of the existing rock spreader, combined with the actual application conditions, the load conditions of the rock spreader are analyzed. The static and dynamic analysis and optimization of the key structures such as the receiving arm, the discharging arm, and the main tower are carried out by using the topology optimization method. The optimized virtual prototype of the whole machine is established to verify its rationality. The research results show that the total weight of key parts such as receiving boom, discharging boom, and the main tower is reduced by about 4.5% (4650 kg), the lower-order vibration frequencies below the fifth order of those parts are not within the resonance range, and the stability of the whole machine is greatly improved, which fundamentally solves the problem of uneven rock stacking caused by impact stability. And, the maximum stress and deflection of the whole machine under the worst working conditions meet the actual requirements. The research ideas and conclusions can provide solutions to prevent the subsidence or local collapse of reclamation areas caused by uneven stacking materials.