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Title: Woody Species Diversity and Soil Nutirents in Relation to Fire Incedence in Selected Sites of Awash National Park, Eastern Ethiopia
???metadata.dc.contributor.*???: Dr. Minassie Gashaw
Prof. Masresha Fetene
Tumtu, Abdiitana
Issue Date: Jul-2005
Publisher: Addis Ababa University
Abstract: The effect of fire on woody species diversity and soil nutrients was investigated in Awash National Park. Sites with fire history from years 2000, 2002, 2004 and unbumed plot were selected within three vegetation types (woodland, grassland and doum palm forest). A total of six sites namely, grassland burned during 2000, grassland burned during 2002, woodland burned during 2002, unbumed woodland, palm forest burned during 2004 and unbumed palm forest were identified. Three random square plots with size of 20 x 20 m were selected within each site. To collect above ground vegetation data three concentric rings were laid within the 20 x 20 m plot. DBH (Diameter at Breast Height), height, frequency and density of woody species were recorded .To collect soil seed bank five random sampling spots were selected within the 20 x 20 m plot and samples were taken at four depths (0 - 0.5 cm, 2.5 - 3 cm, 5.5-6 cm and 8.5 -9 cm) from each spot. For study of soil nutrients soil samples were taken from the 4 comers and middle of the square plot and mixed. To study response of seeds of woody species to heating effect of fire seeds were collected and subjected to temperature levels of 20°C, 60°C, 90°C, 120°C, 150°C and 200°C for 1 minute and 5 minutes duration. Shannon-Wiener index, richness index and similarity index were calculated for the above ground vegetation. ANOVA and independent t-test was used to analyze the data. The result showed less species diversity in the recently burned areas than unbumed and old burned areas. Species density was observed to be high for two species ( Acacia Senegal and Haphaene thebaica) following fire. The soil seed bank was poor in density and species richness for woody species. Most of the woody species subjected to heat shock trial were responded positively at temperature levels of 60°C, 90°C, and 120°C. The result from soil nutrient study showed high values for soil pH, available phosphorus, organic matter, exchangeable calcium and sodium at the burned sites than unbumed and old burned sites. Fire appears to contribute to loss in woody species diversity. Even though the heat from the fire can stimulate germination the poor soil seed bank strategy may not allow fire stimulated germinations. Therefore if the fire regime becomes more frequent woody species could be at a risk of local extinction while fire incidence could contribute to the maintenance of the grasslands against woody species invasion. The increase in soil pH and organic matter values can increase nutrient availability following fire which can favor germination and seedling establishment. The release of phosphorus, calcium and other nutrients can contribute to post fire regeneration and forage quality.
Description: A Thesis Submitted to the School of Graduate Studies Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Dryland Biodiversity
Appears in Collections:Thesis-Plant Biology and Biodiversity Management

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