No abstract

Laut Tawar Lake is located in Aceh Tengah District is the largest lake in Aceh Province. The lake, located at an altitude of 1230 meters above sea level, produces about 13 species of freshwater fish. Fish depik (Rasbora tawarensis), eyas (Rasbora sp.), and relo (Rasbora sp.) are endemic species of Laut Tawar Lake. This study aims to estimate the potential of fish production based on the value of morphoedaphic index. The observation was conducted for one year, from October 2016 until September 2017. The measurement of electric conductivity value of lake waters was conducted on 7 (seven) stations selected purposively in the lake area about 5870 hectares. The results showed that morphoedaphic index value of Laut Tawar Lake ranged from 5.10 to 7.84 with an average of 6.14. Potential of fish production in the lake is 33.47 kg/ha/yr with total potential of fish production of 196.49 ton/yr. The value shows a decrease of 10.93 kg/ha/yr over a period of 22 years. This decrease is caused by changes in morphometry parameters and water quality of Laut Tawar Lake.

Many forests have substantial understorey plants. These plants have an important contribution to soil and water conservation. The similarity index determines the resemblance of species structure and composition in a community. This research is aimed to see the impact and relationship of changes in the allocation of forest areas to the similarity of understorey species. The research was conducted using the line plot sampling method, sized 2 m x 2 m, with the understorey plants observed have been measured from germination to young plant (height 1.5 m). The number of plots in the plantation forest is 480 plots, protected areas 224 plots, and natural forest 96 plots. Determination of the number of understorey plots based on the minimum representative area curve. A Similarity Index was performed to analyze the data.  The results indicated that there is an impact of changes in the forest area on the similarity of understorey species. It is known from the low similarity index value at the research location. It is due to the differences in environmental factors at the two locations such as air humidity, air temperature, the intensity of sunlight, and different patterns of forest area management.

Pesisir Timur Pulau Weh (PTPW) is a water natural reserve conservation area located in the eastern part of Weh Island. The condition of coral substrates in PTPW has suffered a lot of damage based on bleaching cases that have hit Sabang waters in 2016. Coral conditions can be measured by looking at the abundance of fish indicators of the Chaetodontidae group. Therefore, this study aimed to measure coral conditions and the abundance of Chaetodontidae coral fish, as well as analyze the relationship between the percentage of coral cover and the abundance of Chaetodontidae coral fish. Data of coral were collected using the Point Intercept Transect method with a length of 50 meters, while the abundance of fish used the Underwater Visual Census technique and the Belt Transect method with a length of 50 meters and a total belt width of 5 meters. The results showed that the coral conditions in PTPW were in poor to fair condition with the highest cover at The Sumur Tiga site (36.83%) and the lowest at The Ujung Kareung site (11.5%). The highest abundance of Chaetodontidae fish was found at Ujung Seuke site (1253.3 ind/ha) and the lowest was found at Anoi Itam site (186.7 ind/ha). The results of the correlation analysis between the percentage of coral cover and the abundance of Chaetodontidae coral fish showed a positive relationship (r = 0.482), but it was not significant (p>0.05), and the regression equation obtained Y = 17.16x + 166.52 with a determination coefficient of 18.3%, which indicated that the correlation between the two variables was very weak.

Abstract. Sidabukke SH, Barus TA, Utomo B, Delvian. 2021. The undergrowth composition and distribution in different forest area utilization. Biodiversitas 22: 5255-5261. Forests provide natural raw materials to support various human activities and also demonstrate a wide range of biodiversity, both in terms of wildlife and plants. Based on biological resources, undergrowth species form a significant portion of the forest ecosystems and have overgrown the typical wooden plants. These ground cover/undergrowth groups are known to exhibit diverse complexities and a type of basic vegetation existing under the forest stands. Therefore, the purpose of this study is to determine the composition and distribution of undergrowth species in each forest area designation, including industrial, protected and natural forests. The plot technique was employed, with an area of 2 m x 2 m. This involves a total of 480, 224 and 96 plots in the industrial plantations, protected and natural forest areas, respectively. Also, the entire plants in the measuring plot were recorded, starting from the sprouts up to 1.5 m high. Subsequently, the important value index (IVI) and Morisita index methods were applied in the data analysis. The results showed the occurrence of 98, 57 and 33 undergrowth species in industrial, protected as well as in natural forests, correspondingly. Based on the important value index calculations, Sintrong species (Crassocephalum crepidioides) reported the maximum IVI (31.587%) in industrial forest plantations, alongside Senduduk (Melastoma malabathricum) and Paku Wangi (Phymatosorus scolependria) in the protected areas (29.951%) and natural forests (29.551%), respectively. Furthermore, the Morisita index indicated that the undergrowth distribution pattern for the three areas was clustered, uniform and random, but with varying percentages. However, only two distribution patterns, including random and clustered were peculiar to the natural forests.