Impact of Climate and Land use on Plant Diversity, Carbon Storage and Leaf Area Index in the Jimma Highlands, Southwest Ethiopia

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Addis Ababa Universty


The study aimed at the impact of climate and land use on plant diversity, live carbon storage (AGC) and leaf area index (LAI) in the Jimma Highlands of Ethiopia. Data on woody species were collected from 155; 20 m × 20 m sample plots which were subdivided into 2 m×2 m subplots for herbaceous species inventory. Thirty-one plots of one ha each were randomly distributed along a study transect for -measuring diameter at breast height for all woody species with DBH 10 cm. Upward hemispherical images of the forest/tree canopy were taken at 12 points in the 20 m × 20 m plots established within each one hectare plot. Two SPOT5 satellite images (path 134 / row 133) captured simultaneously on 17th December and aerial photographs taken in October 2012 were used for LULC mapping. The transect was classified into five major land use types from SPOT5 images and aerial photography. Natural forest was further separated into the natural forest with coffee shrub/tree beneath and those with no coffee under the canopy based on field observation. Two hundred and eight-seven plant species belonging to 220 genera and 82 families were collected and identified. The highest plant species richness per hectare was recorded from woodland and the least was from the cropland. The highest mean abundance of tree species was recorded from the planation forest and the least was from the pasture. Mean annual temperature and soil pH have significantly explained the variation in herbaceous species richness; sand and clay particles significantly explained the variation in tree species richness. Species richness, abundance and diversity also vary along vertical stratification in semi-forest coffee (SFC) and degraded natural forest (DNF). The highest AGC storage was recorded from the plantation forests (152.25±24.98) followed by DNFs (82.03±32.08) and SFCs (61.52±24.98). Land use types showed significant mean difference in AGC and LAI. Tree species abundance and richness combined, have explained about 82% of the variation in AGC across the land use types. There was significant linear relationship between AGC storage and some climate variables such as mean annual temperature, mean annual rainfall and potential evapotranspiration; between AGC and some edaphic factors such as soil cation exchange, sand and pH. Basal area, richness of shrub, tree and entire plant species combined have significantly explained about 82% and 81% of the variations in LAI_true_v6 and LAI_true_v5 respectively. LAI_true_v6 explained about 75% of the variation in AGC. Mean annual temperature and annual temperature range significantly explained about 21% of the variation in LAI_V5. Climate change under the current and projected scenarios affected the distribution of five plant species across Ethiopia. In conclusion, plant richness, abundance, distribution, carbon storage and leaf area index are affected by land use and climate variables. Key words: Carbon storage, climate change, Jimma highlands, LAI, land use change, plant richness



Carbon storage, Climate change, Jimma highlands, LAI, land use change, Plant richness