The Influence of Land Use Dynamics and Climate Change on Woody Species and Underutilized Wild Edible Plants Conservation in Agroforestry and Adjacent Landscapes of Midakegn District, West Shewa, Ethiopia
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Date
2024-05
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Addis Ababa University
Abstract
Pressures from nature and anthropogenic activities are affecting biodiversity conservation, and thus, understanding the impacts of these pressures is very important with regard to ensuring the long-term persistence of biodiversity at local and global levels. The main goal of this study was to examine the effect of climate change on the distribution range of selected species and land use dynamics on the diversity of woody species and the wild edible plants in West Shewa, central Ethiopia through (1) analyzing and quantifying the spatiotemporal land use dynamics along with identifying the major driving pressures (Paper I); 2) assessing the influence of altitudinal variation, land use types, and wealth class on the woody species diversity potential in terms of species richness, diversity, and structural composition in the agroforestry systems of the study area (Paper II); 3) identifying and documenting underutilized wild edible plants used by the local people of Midakegn (Paper III); and 4) predicting the distribution of suitable habitats of S. afromontanum under climate change (Paper IV). In Paper I, a study on land use change covering 34 years, i.e., from 1986 to 2020 was conducted. Landsat images of 1986, 2003 and 2020 were acquired from Earth Explorer to quantify land use changes in ArcGIS 10.7. Field observations, interviews, and group discussions were held to identify the drivers of these changes. The change detection was done by post-classification comparisons of land cover statistics for each remote sensing dataset and with respect to the complexity of gradients. For assessment of woody species status, a simple random sampling and a systematic random sampling technique for representative village selection and data collection from 114 land plots in different agroforestry were employed following transect lines, respectively. DBH ≥ 2.5 cm and height ≥ 1.5 m were measured and recorded. Pairwise mean comparisons of species diversity and structural composition were computed per study sites, land use types, and economic status of households by employing one-way ANOVA, and vegetation structure bar charts in different distribution classes were drawn using R statistical package version 6.3.1. In paper III, key and general informants were selected by snowball and stratified random sampling methods respectively to collect underutilized wild edible species data. A one-way ANOVA was used for the comparison of ethnobotanical knowledge distribution
between different informant classes. Different ranking exercises were used to measure popularity, multiple functionalities, and threats to those plants in the study district. In Paper IV, potential distribution of S. afromontanum was modeled using the MaxEnt software. For future prediction, RCP 4.5 and RCP 8.5 emission scenarios for 2050 and 2070 years were used. A total of 47 occurrences and 22 environmental variables were considered in the modeling process. The outcome indicated six land use classes, with a substantial decrease in grazing, shrub, and forest lands, while farmland and built-up area indicated intensive increases. The findings also identified both ultimate and indirect causes of land use change in the study district. The expansion of the land use category, mainly farmland, was found to be due to the loss of shrubland, grazing land, and forest-covered areas to afford the ever-increasing population in the study area. A total of 77 woody plant species belonging to 68 genera and 45 families were recorded. Woody species diversity and vegetation structural composition were dissimilar among land use types (P < 0.05). The highest mean species richness and diversity per land plot was computed in homegarden and grazing land, while the lowest species richness and diversity were recorded in cropland woodlots, respectively. A total of 50 UWEPs belonging to 39 genera and 30 families were recorded. The highest numbers of these plants were shrubs and followed by trees. Though there were many reservoir areas, the majority were recorded in highly disturbed natural forests. When viewed in terms of the agro-ecology, the highest number of UWEPs were recorded for midland and followed by lowland. This caused heterogeneity in indigenous knowledge between the local communities. Noteworthy is that edible fruits were the dominant and consumed raw outdoors without further processing. Fresh or dried raw mode of consumption accounted for the majority of consumption, while cooking, fermentation, backing, and boiling are also recorded in the study areas. The computed ranking exercise for factors threatening the long-term persistence of UWEPs revealed that human-induced factors, particularly, habitat destruction at the expense of farm land expansion, overgrazing, fuel wood harvesting, and selective logging for different purposes, were identified as principal factors that caused destructive effects on plant resources. The modeling result indicates that solar radiation, followed by precipitation in the driest quarter, significantly
influences the future potential habitats of the species. The model predicts range reduction trends under both future scenarios. Overall, for sustainable use and conservation of plant biodiversity in various landscapes, integrated investigations from different aspects should be considered to alleviate impacts caused by uncontrolled land use, land conversion, and climate change, which definitely impose negative impacts on woody species and wild edible plants and in turn affect the livelihood of people, particularly farmers
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Keywords
Agroforestery, Climate Change, Diversity, Land Use Dynamics, Wild Edible Plants, Woody Species