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Dersita, Rambey R, Muhtadi A, Onrizal O, Mamurung VR, Hasibuan JS, Tamba IS. 2022. Biodiversity of nekton in the Barumun Watershed, Labuhanbatu District, Indonesia. Biodiversitas 23: 2426-2432. Biodiversity is a very valuable source of germplasm for science and sustainable development. Therefore, research on freshwater biodiversity is very important to support the sustainability of this development. The research investigated three rivers in South Labuhanbatu District, North Sumatra, Indonesia: Barumun, Tasik, and Titi Kembar rivers. This investigation aims to ascertain the composition, distribution, and variety of nekton. From April to August 2020, the trial lasted five months. Nekton samples were collected with the aid of nets and fishing nets. While installed in the afternoon, the nets are removed the following day. Additionally, at each observation point, stocking nets were operated three times. The investigation discovered 38 fish species and one shrimp species. Two species of fish discovered, are protected by the government of the Republic of Indonesia. Both fish species are Tenualosa terubuk, a fish with little protection, and Fluvitrygon signifer, a ray fish with complete protection. The study site's sole shrimp species was the gigantic prawn Macrobrachium rosenbergii in the Barumun river. The index of nekton diversity discovered in the three rivers was not identical. Compared to other rivers, the Tasik river station has a high diversity. This makes the Tasik river rich in fish compared to the Barumun and Titi Kembar rivers. The Tasik river is recommended as water suitable for fish life from these results.

Rambey R, Susilowati A, Rangkuti AB, Onrizal O, Desrita, Ardhi R, Hartanto A. 2021. Plant diversity, structure and composition of vegetation around Barumun Watershed, North Sumatra, Indonesia. Biodiversitas 22: 3250-3256. Watershed ecosystem plays an important role in water and soil conservation which is supported by vegetation around watershed. As such, vegetation analysis is beneficial to assess the current state of watershed vegetation and monitor future changes. Barumun Watershed, located in South Labuhanbatu District, North Sumatra Province, Indonesia, is under threat due to habitat degradation and land conversion for plantation and agriculture. This research aimed to investigate the diversity, structure and composition of vegetation in the Barumun River including its smaller streams (rivulets). Data were collected using a combination of line transect and quadratic plots arranged systematically. The total observation plots were 48 plots, consisting of 24 plots in Barumun River, 12 plots in Tasik Rivulet and 12 plots in Titi Kembar Rivulet. The results documented a total of 51 plants in the studied sites in Barumun Watershed in which 37 species were found in Barumun River, 20 species in Tasik Rivulet and 17 species in the Titi Kembar Rivulet. Plant species consisted of several habitus including herbs, palms, shrubs, climbers and trees. The trees consisted of 22 species (43.13%), herbs 22 species (43.13%), climbers 3 species (5.88%), shrubs two species (3.92%), and palm two species (3.92%). The highest Importance Value Index (IVI) for tree community was recorded in the Barumun River from Hevea brasiliensis (108.28), followed by Cryptocarya sp. (123.24) in the Titi Kembar Rivulet. In addition, the highest IVI for pole, sapling, seedling, and shrub was recorded from Muntingia calabura (Barumun River), Nauclea orientalis (Tasik Rivulet), Psychotria viridiflora (Tasik Rivulet), and Calamus axillaris (Titi Kembar Rivulet), respectively. The plant diversity in Barumun Watershed was categorized from low to moderate level of richness.

Angke-Kapuk Protected Forest with total area 44.76 ha is part of the Tegal Alur-Angke Kapuk mangrove forests. Therefore, this forest has important role as an interface between terrestrial and marine ecosystems, whether physical, biological or social-economic aspects, todetermine mangrove ecosystem as a productive and unique ecosystem in the coastal area. However, the study of floristic of the mangrove vegetation in this forest has never to be done previously. According to the study on September to November 2003, in this forest found 8 species of mangrove trees. The tree species can be classified into two groups. The first group is true mangroves (7 species), i.e. Avicennia officinalis, Rhizophora apiculata, R. mucronata, R. stylosa, Sonneratia caseolaris (major component), Excoecaria agallocha, and Xylocarpus moluccensis (minor component). The last group is mangrove associate, i.e. Terminalia catappa. In this forest also found 7 tree species, i.e. Bruguiera gymnorrhiza, Calophyllum inophyllum, Cerbera manghas, Paraserianthes falcataria, Tamarindus indicus, Acacia mangium, and A. auriculiformis as introduced species. The growth level of B. gymnorhiza, C. inophyllum and C. manghas up to now is seedling and sapling, while the growth level of another introduced species is till in pole and tree.© 2005 Jurusan Biologi FMIPA UNS SurakartaKey words: mangrove tree species, Angke-Kapuk Protected Forest.

Ecological studies on mangrove forest in East Coast of North Sumatra have been carried out with field work in transect method and laboratory analyses. This study would be covered on floristic composition, abrasion, green belt, soil properties, and water quality of mangroves. Land system map and landsat TM imagery (year 1996 coverage) as main material in this study were used and overlay to determine training area. Based on vegetation inventory found that 20 mangrove species and by vegetation analyses, we known that Avicennia marina was as dominant tree species of seedling and sapling stage. Tree stage was not found in the area, yet. Environment properties of the mangrove area were suitable for mangrove growth and rehabilitation with the exception of pyrite content in the mangrove soil. Average of mangrove green belt was 25 m with range from 10 to 80 m in KJP (Kajapah) land system and 30 m with range 10 to 50 m in PTG (Putting) land system. Abrasion rate in the area was very high, i.e. 6 m per year in KJP land system, and 10 m per year in PTG land system.© 2008 Jurusan Biologi FMIPA UNS SurakartaKey words: mangrove, abrasion, green belt, soil properties, water quality, North Sumatra

Onrizal, Mansor M. 2015. Status of coastal forests of the Northern Sumatra in 2005 (after 2004's tsunami catastrophe) Biodiversitas 17: 44-54. The first intensive ecological study of coastal vegetation including mangrove, littoral and peat swamp forests after the 2004 tsunami catastrophe in Northern Sumatra was conducted from January to December 2005 where 16 sampling sites along 2960km coastline in Northern Sumatra were selected. In each site, one quadrate of 100 m x 100 m was established and divided into 10 m x 10 m subplots where all standing trees of ≥ 2 cm diameter at breast height (DBH) were identified to species level and measured. Overall 54,871 standing trees were recorded in 16 sites comprising 84 species in 65 genera and 37 families. Mangrove trees Rhizophora apiculata and R. mucronata were widely distributed and are dominant in most of the sampling sites. This indicated that these species have stronger resilient compared to other species. The highest value of Shannon-Wiener index of species and Evenness index of species was 3.03 and 0.85, respectively. It means that some sites were rich in biodiversity which harbors various species of plants. Subsequently, undisturbed coastal forests including mangroves, littoral forests and peat swamp forests characterized by dense stands, mixed species and structures play an important role in coastal protection against tsunami. Therefore, the coastal vegetation is needed to conserve the biodiversity and to maintain the production capacity as part of sustainable and longlasting vegetation bioshield.

The objective of the research was to know species composition and structure of ex-burned heath forest. Field research was carried out from 23 June to 5 July and 10 to 25 September 2004 on the foot-slope of Semujan Hill, Danau Sentarum National Park, West Kalimantan. Ten-sample units (SU) with each size 10 x 10 m are placed based on random sampling method. On each SU, trees with diameter  2 cm cm were identified and the diameter (DBH) and height are recorded. Fourteen tree species were found within a 0.1 ha SU, consisting of 12 genus and 8 families. Tree density is exponentially decreased from trees with small diameter to trees with big diameter.Key words: species composition, forest structure, ex-burned heath forest, Danau Sentarum National Park, West Kalimantan.