Woody Plant Species Diversity, Land Cover Dynamics and Ethnobotany of Medicinal Plants in Habru District, Amhara Region, Ethiopia
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2024-06
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Addis Ababa University
Abstract
Geospatial techniques are vital for examining the dynamics of land use land cover (LULC) in specific areas. In Ethiopia, a blend of human activities and natural factors is threatening the vegetation, leading to the degradation and fragmentation of forests. The people of Habru District in the North Wollo Zone of Amhara Region, Ethiopia, have a rich tradition of utilizing local plant resources for a variety of needs, particularly for traditional herbal remedy preparation and use. However, the district has not been adequately studied for its land use dynamics, ecological and ethnobotanical resources linked with the associated knowledge. This gap highlights the necessity for detailed studies on woody plant species diversity in relation to land use land cover dynamics and ethnobotanical study of medicinal plants and their uses within the study area.
Moreover, Ethiopia's culture on the utilization of traditional medicine as a primary healthcare system for treating human diseases calls for empirical research to validate these practices against infectious diseases. Therefore, this study was aimed to examine the LULC change dynamics in Habru District for a period of 36 years (1985 – 2021), assessing the woody species composition, structure and plant community analysis of Gerado, Micha and Mekelet Forest Patches, documenting and analyzing medicinal plant species used by the local communities to treat human ailments along with the associated traditional knowledge and practices and empirically validating the efficacy of selected traditional herbal remedies used by the local people at present.
This study, employed remote sensing methods to analyze the temporal and spatial changes in land use land cover within the study area, using Landsat images from 1985 - 2021. To complement this, Focus Group Discussions (FGDs) and interviews with key informants were carried out to collect insights on the factors influencing LULC changes. Image classification was performed using the supervised classification technique, specifically employing the minimum likelihood algorithm for land use mapping. For vegetation analysis, a major category consisting of all the woody species (trees and shrubs) having ≥ 2.5 cm diameter at breast height were collected from a total of 95 plots (20 x 20 m2) laid systematically from Gerado (43 plots), Micha (28 plots) and Mekelet (24 plots) forest patches. The Shannon-Wiener diversity index was used to quantify the woody species richness and evenness of the forest patches. This study also determined plant community types and examined their correlation with environmental factors using agglomerative hierarchical cluster analysis and Redundancy Analysis (RDA) in the R software environment. The ethnobotanical data were collected using semi-structured interviews, guided field walks, focus group discussions, and market surveys. A total of 388 informants (250 males and 138 females) were selected from all 13 kebeles (subdistricts) within Habru District using systematic random sampling technique, and 42 key informants were purposively selected in each from among the randomly identified informants. Descriptive statistics, preference ranking, direct matrix ranking, informant consensus factor and fidelity level were applied for data analysis. For antimicrobial and phytochemical screening, the candidate medicinal plants were selected considering their high informant consensus and fidelity level values for their efficacy in treating infectious diseases in the area. Ethanol and aqueous extracts were prepared from the plant materials, and their antibacterial activities were evaluated against standard grampositive and gram-negative bacterial strains. The minimum inhibitory concentration (MIC) was determined using the broth dilution method. Furthermore, phytochemical screening was performed using standard qualitative tests to identify various secondary metabolites.
The study results revealed that there was a substantial expansion of settlement areas in Habru District, with a notable decrease in shrubland and forestland. Conversely, cultivated land and settlement areas increased, indicating significant anthropogenic impacts on natural landscapes.
This study investigated the primary drivers of LULC change in Habru District. The analysis identified cultivated land expansion, settlement area expansion, charcoal production, firewood collection, and tree cutting as the major proximate factors influencing LULC change.
Additionally, the study explored underlying causes, including population growth/pressure, land tenure insecurity, economic challenges (poverty and unemployment), and climate change (precipitation variability). A total of 55 woody plant species were recorded from the three forest patches. The study also identified four distinct plant community types, influenced by factors like altitude and human activities such as tree cutting. Of these, 35 woody plant species, constituting (64%), were identified as medicinal plants used by the local people. Furthermore, a total of 134 medicinal plant species in 110 genera and 54 families used in traditional medicine against human ailments in Habru District were documented, highlighting the district’s significance in biodiversity conservation and primary healthcare delivery. High consensus factors for gastrointestinal and parasitic ailments (ICF = 0.85), febrile diseases (ICF = 0.84), and cultural conditions (ICF = 0.84), highlight the community's reliance on medicinal plants. Multipurpose plants such as Solanum somalense Franchet. (91.3% FL), Ocimum lamiifolium Hochst. ex. Benth. (88.9% FL), and Verbascum sinaiticum Benth. (85.7% FL) exhibited notable healing potentials. Of the documented medicinal plants, only 16.4% are marketable, including species like Terminalia brownii Fresen. Myrtus communis L., Ruta chalepensis L., Olea europaea L. subsp. cuspidata (Wall. & G.Don) Cif., Allium sativum L. and Capsicum annuum L., commonly found in local markets. Ethanol extracts of selected plants (Solanum somalense Franchet., Withania somnifera (L.) Dunal and Calpurnia aurea (Ait.) Benth.) showed promising antibacterial activity against specific bacterial strains. The presence of secondary metabolites like steroids, alkaloids, and flavonoids underscores the pharmacological potential of these plants.
The study underscores the profound impact of anthropogenic activities on natural ecosystems and the crucial role of traditional knowledge in leveraging biodiversity for healthcare. The study emphasizes the critical need for strategies addressing LULC change drivers to protect natural resources and ensure sustainable ecosystem services to contribute to livelihoods. It highlights the inadequacy of current management in conserving forest patches and suggests tailored, community-based conservation to improve ecosystem resilience. Recognizing the deep connection between communities and medicinal plants, the study advocates for biodiversity conservation, sustainable healthcare, and the preservation of traditional knowledge, underscoring the mutual dependence of human societies and natural environments.
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Keywords
Woody Plant Species Diversity, Land Cover Dynamics, Ethnobotany of Medicinal, Plants in Habru District, Amhara Region, Ethiopia