Impact of livestock grazing on vegetation in pastoral areas of Kasese district in and adjacent Queen Elizabeth Conservation Area, Western Uganda

Abstract

Conservation areas contribute significantly to the wellbeing of humanity yet these continue to be threatened by degradation arising from different factors including poorly managed livestock systems. This study was conducted in pastoral areas of Kasese district in and adjacent Queen Elizabeth Conservation Area in Western Uganda and overall objective was to contribute to the improved knowledge on dynamics of livestock grazing on vegetation in pastoral areas of Kasese district. For spatial and temporal vegetation changes, four Landsat satellite images of 1984, 1995, 2006, and 2017 were obtained and Normalized Difference Vegetation Index (NDVI) values were calculated. Additionally, transect/quadrat method was used to determine plant species diversity and richness in six grazing hot spots, each stratified as grazing intensity category: Ungrazed, Lightly, Moderately and Severely grazed. In each category, sample quadrats were established and a total of 240 quadrats of 5mx5m and 240 sub quadrats of 1 x 1 m were utilized. Two plant growth forms (Shrubs/forbs and grasses) were examined. A social-economic field survey was also conducted and semi structured questionnaires were administered to pastoralists. Fiftyfour households per sub-county were randomly selected and interviewed. Plant species diversity and richness was calculated among different grazing intensity categories using Shannon−Wiener index (H) and Margalef’s Index. Both One and Two-way analysis of variance (ANOVA) were used to assess whether livestock grazing had significant effect on vegetation in the strata. Results from the analysis revealed that Short and Dry grassland, Low stocked grassland and Well stocked grassland had an increasing linear trend, while Well stocked woodland spiked and low woodland had a drastic decline. Major reduction in vegetation cover was experienced between 2006 and 2017 and this is partly attributed to livestock overgrazing. Moderately grazed areas had the highest plant diversity of 4.41 based on Shannon wiener index while (2.12) the lowest was in Severely grazed areas. A total of 167 pastoralists were interviewed, their livestock totaled 5,982. The parish with highest number of cattle was Nyakatonzi with 2,299 and the lowest Hima with 85. The results show a varied grazing pattern of livestock mostly grazed in the park in dry season and other places in wet season. There were eight grazing hot spots, Kagando and Nyamugasani were the most frequented ones. In conclusion, grassland increased, low woodland spiked, while well stocked woodland declined drastically. Overgrazing resulted into low species diversity, richness and cover in the study sites. Moderate and Light grazing positively influenced plant species richness and diversity in Hamukungu and Katwe. The livestock populations has drastically increased roughly five times. There was change in livelihood strategy of pastoralists from transhumance to sedentary. The overly frequented grazing hotspots were Kagando and Nyamugasani in QENP.