Ecological, Floristic and Ethnobotanical Studies in and Around Wejig-Mahgo-Waren Massif Forest Patches in Southern Tigray, Ethiopia
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Date
2019-05-02
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Addis Ababa University
Abstract
There is a declining trend of biodiversity in general and plant diversity in particular. This trend is leading
to the loss of the associated indigenous and local botanical knowledge in Ethiopia, which is more severe
in the northern highlands than elsewhere in the country. The purpose of this research was to study
vegetation composition, soil seed bank and to document associated ethnobotanical and management
practices applied by the forest fringe communities in and around Wejig-Mahgo-Waren Massif Forest
area. Vegetation data were collected from a sample of 150 quadrats (each 20 m x 20 m) placed in ten
transect lines, which were systematically laid. All vascular plant species were recorded. Diameter at
breast height was measured and seedlings and saplings were counted and recorded. Height and
percentage cover abundance were estimated. Soil samples were collected from 75 quadrats down to 0-5
cm and 5 -10 cm depth. Stratified random sampling of 309 informants was performed for collection of
data on indigenous knowledge, of social classes associated with the forest and the resources in it. Thirty
key informants were purposively selected with the help of local administrators, elders and other
community members for collection of ranking exercises. For collection of ethnobotanical data, semistructured
interview, guided field walks and focus group discussions were applied. Basal area, density,
frequency, importance value index, Shannon-wiener diversity index, cluster analysis and ordination were
computed on ecological data. Density, composition, depth distribution and Sorensen coefficient of
similarity were computed for soil seed bank analysis. Ethnobotanical analytical tools, including
preference ranking, informant consensus factor, fidelity level, direct matrix ranking and cultural
significance index were employed to describe the reciprocal relationship between the forest vegetation
and forest fringe communities. Vegetation study revealed a total of 264 plant species belonging to 162
genera and 82 families. Woody (45.45%) species were higher than herbs (42.04%). Asteraceae (27
species, 32.93%), Poaceae (24 species, 29.27%) and Fabaceae (23 species, 20.05%) were the dominant
families in terms of number of species. Five plant communities were identified in the forest vegetation,
namely Cadia purpurea – Carissa spinarum, Olea europaea subsp. cuspidata – Juniperus procera,
Dodonaea angustifolia – Acacia abyssinica, Erica arborea – Myrsine africana and Acacia etbaica –
Acacia tortilis. The highest (3.87) and the least (3.21) Shannon-Wiener diversity indices were found in
communities two and five, respectively. Altitude, slope, livestock grazing and human impacts were the
factors influencing species distribution. From soil samples, the total number of species recorded was 54,
representing 42 genera and 23 families. The number of viable seeds in the soil samples corresponded to a
seed bank density down to 10 cm was 1115 m-2. Herbs (85.16%) and woody species (14.84%) were the
plants counted from the germination assay. Soil Seed bank and standing vegetation shared 36 species and
their similarity was 23 %. The informants viewed the forest as an important entity for attraction of rain
and for wildlife habitation followed by beekeeping and foraging as well as for sourcing straw and
fuelwood. Of 79 plant species differentiated as useful to the community, 52 (66%) were used in traditional
medicine (human and livestock), 28 (35%) as livestock fodder/ forage and 27 (34%) were recognized as
honeybee forage. The highest informant consensus factor values were calculated for dermatological
ailments (0.98,) followed by external injuries, bleeding and snakebites (0.92). The highest fidelity level
(96.15%) was recorded for Verbascum sinaiticum followed by Withania somnifera (89.47%).
Deforestation, agricultural expansion, fuelwood collection, grazing and settlement in decreasing order
were considered responsible for forest resources depletion. Both the associated indigenous knowledge
and the forest resources were under pressure. Thus, to restore the forest in the shortest possible time,
restoration strategy that combines planting of seedlings of indigenous species and natural restoration
techniques need to be applied.
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Keywords
Multiuse, Plant Communities, Restoration, Tigray, Wejig-Mahgo-Waren Forest