Factors Determining the Population Structures of Festuca Macrophylla Hochst. Ex A.Rich. And Helichrysum Splendidum (Thunb.) Less In Guassa Community Conservation Area, Amhara Regional State, Ethiopia.
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Date
2018-06-05
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Addis Ababa University
Abstract
Several studies have been undertaken in afroalpine ecosystem of Ethiopia, to assess the diversity of flora mainly focusing on woody species composition. However, the information on the factors that affect the interaction of plant communities and how this interaction mediates the population structure along elevational gradient is lacking. Hence, the objective of this study is to examine the factors that determine the structure and interaction of Festuca macrophylla and Helichrysum splendidum plant species. The study was conducted in Guassa Community Conservation area that belongs to the afroalpine ecosystem and is located in North Showa Zone of Amhara Regional state, of Ethiopia. Following systematic sampling approach, two transects that were 200m far from each other were laid out along the altitudinal gradient (3300–3500m a.s.l.). On these transects, main sample plots were laid down at the interval of 100m to collect data. Moreover, within the main plots, five subplots (size, 1m 1m each) that were arranged four at the corner and one at the center were also used to collect data and soil samples. In total, 30 main plots (15 from each transect) were laid to collect data. Here, from each subplot, composite soil samples were taken from the top layer (0-20cm depth) and by sum 30 samples were collected for soil nutrient analysis along with an altitudinal gradient. For soil seed bank study, first, the vegetation was stratified into three types as H. splendid population, F. macrophylla population and H. splendidum and F. macrophylla community. From each of this vegetation type, 10 main plots (5m 5m) where within which five subplots that were arranged four at the corner and one at the center (1m 1m each) were randomly laid to collect composite soil samples from three layers (i.e., litter, 0-3cm and 3-6cm). In total, 90 composite samples (i.e., 10 from each type) were collected for soil seed bank study. The soil samples were collected using the plastic bags to retain the moisture contents and transported to Addis Ababa University. The soil nutrient analysis was performed at national soil laboratory while the soil seed bank study was undertaken at Addis Ababa University. Data were analyzed using general linear model (glm) with Poisson distribution using R statistical program and one-way ANOVA. The result indicates altitude, disturbance intensity, and herbivore were negatively correlated with abundance of the two species. The one-way ANOVA showed no significant variation between the three stratified site and soil properties. Total species abundance significantly affected by available phosphorus (Av, p=0.004) and Organic matter (p=0.007). Vertical distribution of soil seed bank of H. splendidum shows significant difference (P<0.001) while F. macrophylla lacks significant difference. Overall, the current management system might be worthy and favoring the expansion of H. splendidum and declining F. macrophylla and should be changed by other well studied management approach system.
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Keywords
Festuca Macrophylla, Population Structure, Guassa Conservation, Helichrysum Splendidum