Floristic Composition, Structural Analysis and Land use/Land Cover Change in Bore- Anferara-Wadera Forest, Southern Ethiopia
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Date
2017-06
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Addis Ababa Universty
Abstract
This study was conducted in Bore-Anferara-Wadera forest, southern Ethiopia, to
investigate the floristic composition, vegetation structure, regeneration status and land
use/land cover change. Vegetation data were collected from 112, 30 m x 30 m sample
plots laid for trees at every 400 m distance along line transects and 5 m x 5 m and five 1
m x 1 m subplots for saplings and herbs, respectively. The regeneration status of woody
species was assessed by employing total count of all seedlings within the main sample
plot. Environmental variables such as altitude, slope, and exposure were measured in
each sample plot. Soil samples were taken from two layers (0-25 and 25-50 cm) at five
points in each sample plot and soil sample from these five points were mixed to form a
composite sample. In each sample plot, woody species ≥ 3 m were counted and cover
abundance values estimated as well as height and diameter at breast height were
measured. Hierarchical cluster analysis was used to identify plant communities and
synoptic values for identification of the dominant species for naming plant communities.
Density, frequency, basal area and importance value index (IVI) of woody species were
also computed. Shannon-Wiener diversity index was used to assess species richness and
evenness. Sorensen's similarity coefficient was used to measure similarities among
communities and between Bore-Anferara-Wadera and eight Afromontane forests in
Ethiopia. Canonical correspondence analysis (CCA) was used to assess the relationship
between plant community types and environmental variables. Moreover, three periods
land sat images (1986 TM, 2000 ETM+ and 2014 OLI/TIRS) were acquired and analyzed
by using remote sensing and GIS technologies to generate information on the temporal
changes in land use and land cover types. A total of 136 vascular plant species belonging
to 119 genera and 63 families were recorded. About 4.4% of the species were endemic to
Ethiopia and 11.8 % of the species were new records for the Sidamo floristic region of
the flora area. The overall Shannon-Wiener diversity and evenness values of Bore-
Anferara-Wadera forest were 3.84 and 0.78, respectively. Size class distribution of
woody species across different DBH and height classes indicated the relatively high
proportion of individuals at lower classes, indicating impacts of past disturbance.
Analysis of population structure and regeneration status of the forest revealed various
patterns of population dynamics where some species were represented by few mature
plants only suggesting that they are on the verge of local extinction and thus immediate
conservation measures should be taken. Community classification using the free
statistical software R version 3.1.1 resulted in four, namely Acanthus eminens -
Dracaena afromontana, Syzygium guineense subsp. afromontanum - Ocotea kenyensis,
Pouteria adolfi-friederici - Psychotria orophila and Scolopia theifolia - Teclea nobilis
community types. Canonical correspondence analysis (CCA) result showed that altitude
and slope were among the main environmental variables in determining patterns of
species distribution and plant community formation. The results of land sat image analysis revealed that agricultural land and built up area are expanding rapidly at the
expense of other land use and land cover types. Forest and shrub land areas have
declined drastically over the last 28 years. Population pressure, deforestation, land
tenure system, and forest fire were the main driving forces responsible for the change in
land use and land cover types in the study area. Therefore, a joint management and
conservation measures should be taken by the government, local people and other
stakeholders in order to reduce and/or stop the fast rate of vegetation cover declining
and sustainable utilization of the forest resources in the study area.
Keywords: Anferara, Biodiversity, Conservation, Land use/land cover, Plant community
Description
Keywords
Anferara, Biodiversity, Conservation, Land use/land cover, Plant community