Impact Of Climate And Land Use On Plant Diversity Carbon Storage And Leaf Area Index In The Jimma Highlands Southwest Ethiopia

The study aimed at the impact of climate and land use on plant diversity, live carbonrnstorage (AGC) and leaf area index (LAI) in the Jimma Highlands of Ethiopia. Data onrnwoody species were collected from 155; 20 m × 20 m sample plots which werernsubdivided into 2 m×2 m subplots for herbaceous species inventory. Thirty-one plots ofrnone ha each were randomly distributed along a study transect for -measuring diameterrnat breast height for all woody species with DBH 10 cm. Upward hemispherical imagesrnof the forest/tree canopy were taken at 12 points in the 20 m × 20 m plots establishedrnwithin each one hectare plot. Two SPOT5 satellite images (path 134 / row 133) capturedrnsimultaneously on 17th December and aerial photographs taken in October 2012 werernused for LULC mapping. The transect was classified into five major land use types fromrnSPOT5 images and aerial photography. Natural forest was further separated into thernnatural forest with coffee shrub/tree beneath and those with no coffee under the canopyrnbased on field observation. Two hundred and eight-seven plant species belonging to 220rngenera and 82 families were collected and identified. The highest plant species richnessrnper hectare was recorded from woodland and the least was from the cropland. Thernhighest mean abundance of tree species was recorded from the planation forest and thernleast was from the pasture. Mean annual temperature and soil pH have significantlyrnexplained the variation in herbaceous species richness; sand and clay particlesrnsignificantly explained the variation in tree species richness. Species richness,rnabundance and diversity also vary along vertical stratification in semi-forest coffeern(SFC) and degraded natural forest (DNF). The highest AGC storage was recorded fromrnthe plantation forests (152.25±24.98) followed by DNFs (82.03±32.08) and SFCsrn(61.52±24.98). Land use types showed significant mean difference in AGC and LAI.rnTree species abundance and richness combined, have explained about 82% of thernvariation in AGC across the land use types. There was significant linear relationshiprnbetween AGC storage and some climate variables such as mean annual temperature,rnmean annual rainfall and potential evapotranspiration; between AGC and some edaphicrnfactors such as soil cation exchange, sand and pH. Basal area, richness of shrub, treernand entire plant species combined have significantly explained about 82% and 81% ofrnthe variations in LAI_true_v6 and LAI_true_v5 respectively. LAI_true_v6 explainedrnabout 75% of the variation in AGC. Mean annual temperature and annual temperaturernrange significantly explained about 21% of the variation in LAI_V5. Climate changernunder the current and projected scenarios affected the distribution of five plant speciesrnacross Ethiopia. In conclusion, plant richness, abundance, distribution, carbon storagernand leaf area index are affected by land use and climate variables.rnKey words: Carbon storage, climate change, Jimma highlands, LAI, land use change,rnplant richness

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