This paper is aimed to study the tree line dynamics of Himalayan silver fir (Abies spectabilis D. Don) based on its tree-ring data and age stand distribution at Langtang National Park, Central Nepal. Climatic response on radial growth, recruitment of A. spectabilis and its age distribution are carried out. The average tree density of the species in the study area (total 48 plots of 20 m x 20 m) was 236 no/ha while that for sapling and seedling in the study area was 255 and 350 no/ha, respectively. The stand character and age distribution of the species showed a high level of recruitment in the recent decades, with decreased in average age along with increased altitude. Tree-growth climate relationship showed negative response with temperature of March-May. Upward advancement of tree line is expected in the coming recent decades though not necessarily uniform through the line.DOI: http://dx.doi.org/10.3126/njst.v12i0.6506 Nepal Journal of Science and Technology 12 (2011) 220-229
A study was carried out at the treeline ecotone (3,730m-3,950m asl) of Langtang National Park in central Nepal with an aim to document the impact of climatic warming on ecological chracteristics. Three sampling sites were selected at Chaurikharka and Lauribina, where no serious anthropogenic pressure was noticed. The nearest meteorological station has records of climatic warming in recent years. Six tree species and three shrub species belonging to seven families were enumerated from the study plots. The average basal area for tree species was found to be 20.56 m2 per ha while average tree density was found to be 734 trees per ha with Abies spectabilis as dominant species. The mean DBH (diameter at breast height) of tree species was found to be 15.8 cm (max. 115.5cm). Density of dead trees accounted 2 no. per ha with basal area 0.195m2 per ha. Average sapling and seedling density of tree species per ha was observed to be 1,590 and 831 respectively. The average sapling and seedling density of A. spectabilis was 255 and 350 per ha respectively. Similarly, average shrub density (per ha) for the area was found to be 9,609 no/ha. The stand character showed that there was high level of recruitment of A. spectabilis in the recent years. The presence of sapling and seedling of A. spectabilis at higher altitude showing linear relationship with canopy coverage indicated prospects for a gradual and upward shift of A. spectabilis with increased temperature. Key words: Abies spectabilis; regeneration; climate change; DBH DOI: 10.3126/njst.v11i0.4132Nepal Journal of Science and Technology 11 (2010) 107-114
Soil parameters such as moisture content, pH, resistivity, oxidation-reduction potential, chloride and sulfate ions can give an indication of the soil corrosivity towards the buried-galvanized steels and cast-iron pipelines used to supply the drinking water in Nepal. Present research work was focused to examine such soil parameters collected from Kamerotar town planning area of Bhaktapur district of Nepal. Concentrations of these soil parameters measured in this study are found as: moisture content (18-77%), pH (3.0-9.3), resistivity (11600-71400 ohm.cm), oxidation-reduction potential (87-426 mV vs SHE), chloride (28-135 ppm) and sulfate (20-226 ppm). These soil parameters gave an indication of "moderately corrosive" to "mildly corrosive" behavior of soils on the buried-galvanized steels and cast-iron pipelines used in the study area. It was found a good correlation between the soil resistivity and moisture content as well as the chloride content in soils. The soil resistivity was generally decreased with increasing both the moisture and chloride contents in soils.
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