ECOLOGY AND VEGETATION COMPOSITION AT HIGH LAND PEAT IN TOBA PLATEAU, NORTH SUMATERA, INDONESIA

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Date
2010-08
Authors
AZVI, TAUFIQ SIDDIQ
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Abstract
This study was conducted at the highland peats of Toba Plateau in North Sumatera, Indonesia to determine the plant diversity, soil textures, soil nutrient contents, air temperature, humidity and precipitations of the highland peat areas. In addition, bird observations and local human activities were recorded. Four Sampling plots of sizes 100m x 100m (4 ha) were established in the study area and the plots were further divided into 400 subplots each measuring 10 m x 10 m. Four sampling sites were represented by (a) Secondary forest (flooded area and dried area), (b) mining area, (c) pine forest and (d) agriculture area. A total of 60 plant species from 40 families were identified. Dry area contains the higher number of species which were 55 species from 38 families. Flooded secondary forest area had 24 species from 19 families while mining area had 10 species from 8 families. Eighteen species from 16 families were recorded from the pine forest and 1 0 species from 9 families were found in agriculture area. Two species of fern, Dicranopteris pubigera (Gleichiniaceae) and Blechnum indicum (Blechnaceae) were the common species recorded during this study. Shannon-Wiener Diversity Index (H') showed that the highest diversity index was in flooded area (2.17) and the lowest was in mining area (0.81). The percentage of invasive (weedy) species was very high with 68%, whereas native species was only 32%. Based on modified Morisita's index similarity, vegetation at Toba highland peat can be divided into three groups. The first group was found on dry area and pine communities and the second group was on mining XVl area and agriculture area and the third was flooded area. Soil colour of highland peat ranges from very dark brown colour (lOYR 2/1) to very black colour (lOYR 2/2), bulk density ranges from 0.23 g/cm3 to 0.40 g/cm3 • The peat depth ranges from 50 em to 85 em in most places but in agriculture area the depth was 2 m and in mining area more than 9 m. The soil acidity ranges from 3.58 to 4.72. The soil nutrient content nitrogen (N) ranges from 4,500 ppm to 13,800 ppm, phosphorous (P) from 14.31 ppm to 288.90 ppm, potassium (K) from 11.7 ppm to 280.8 ppm, calcium (Ca) from 22.0 ppm to 434.0 ppm and magnesium (Mg) from 4.8 ppm to 100.8 ppm. Generally, the temperature of these study sites was cool which was similar to other highlands. Therefore, these areas are good for cultivated of seasonal crops. A total of 21 birds species belonging to 15 families were recorded during this study. The species diversity index of pine community area was the highest with the value of 2.52, whereas at mining area no species was found. Bubulcus ibis was the common bird species with 13 individuals recorded during 15 days of observation. Farming and peat mining were the main human activities observed at highland peat area
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ECOLOGY AND VEGETATION COMPOSITION
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