Vegetation, Land Use Pattern and Soil Seed Bank Composition Along Altitudinal Gradient From Lake Tana to Mount Guna, South Gondar, Northern Ethiopia.
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2018-04-03
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Addis Ababa University
Abstract
Vegetation distribution, Land use pattern and soil seed bank composition along altitudinal gradients from Lake Tana to Mount Guna, South Gondar, Northern Ethiopia.
Birhanu Belay Telake, PhD Dissertation
Addis Ababa University, 2018
The study area covers two watersheds (Rib and Gumara) occurring between Lake Tana and Mount Guna with elevation ranges between 1781 (near Lake Tana), and 4102 m asl (at Guna Mt.) which harbors different habitats. The study was conducted with the objectives of (i) investigating floristic composition, community types and vegetation structure, (ii) identifying the most important environmental predictors used to build habitat suitability Model for prioritized invasive species, (iii) evaluating soil seed bank composition, density and its implication for restoration, and (iv) determining the trend, rate and extent of LU/LC change for the period 1984-2017. Preferential sampling technique was used to establish 98 plots, 20 x 20 m each. The data was analyzed using Rx64 3.4.2 software packages. In aboveground vegetation, a total of 342 plant species were identified, of which 97.53% were angiosperms, 5.84% endemic, 3.51% invasive and 52.05% were herbs. Asteraceae was the most dominant family with 47 (13.74%) species. Five community types were identified, of which Cynodon dactylon and Eleusine indica Community type I harbors 30.31% of the species. About 22.08% of the total IVI value calculated for Chionanthus mildbraedii (6.63%), Juniperus procera (5.89%), Maytenus arbutifolia (4.87%), and Syzygium guineense (4.69%). Maximum entropy (Maxent) indicates that the highest contribution to predict the spatial distribution of Senna didymobotrya was recorded from Classified Map (41%), and elevation (33.2%). Among 17 environmental parameters, only nine were significant at p≤0.05. In the soil seed bank, 12,896 individuals were extracted from 392 soil samples laid on 15 x 15 cm are represented by 140 species, 103 genera and 44 families. Poaceae was the most dominant family with 32 (22.86%) species. Seven LU/LC types were identified using ArcMap 10.3.1: Cropland, Forest, Grassland, Settlement, Shrubland, Water, and Wetlands. Cropland, Water and Settlement show an increasing pattern while Grassland, Shrubland and Wetlands continuously decrease with time series. But Forest showed an irregular pattern. It is hoped that this study will provide information for decision-makers and academicians on the vegetation status, long-term LU/LC changes, drivers and impacts of Rib and Gumara catchments in order to take appropriate measures.
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Vegetation, Lake Tana, Structure, Land Use Land Cover, Mt. Guna, Predictor, Regeneration, Soil Seed Bank