Impact of Human Activities on Carbon Stocks and Implications on Sustainability of Community Livelihoods in Kanyabaha Wetland in Rukiga District, Uganda
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Date
2025-10
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Kenyatta University
Abstract
Climate change in addition to utilization of land and natural resources can negatively impact
biodiversity, hydrology and soil carbon stocks of tropical wetlands, thereby negatively impacting the
sustainability of wetland-dependent livelihood activities. Wetland cover has been steadily declining
in Uganda primarily due to rapid population growth thereby rising food consumption and settlements.
This study assessed the impact of wetland-dependent livelihood activities on carbon stocks and plant
species diversity in Kanyabaha wetland, Rukiga District, Uganda, with a focus on carbon stock
variations, land use changes affecting carbon sequestration and the implications for plant species
diversity and local community livelihoods. The study combined both scientific methods and socio
economic survey designs. Landsat images containing multi-temporal datasets covering a period from
1990 to 2021 were processed using remote sensing software. Field verification was conducted through
ground truth validation. Simpsons, Shannon-Wiener and Pairwise Jaccard diversity indices were
applied to quantify vegetation diversity. Peat soil and vegetation samples were analysed to assess the
carbon stocks. The socio-economic survey was conducted using questionnaires administered to 388
respondents across six villages found in the study area. Three key informant interviews and six focus
group discussions were also conducted to purposively selected informants. Data were analysed using
ANOVA, Chi square and regression analysis. The results of the study revealed that during past 30
years, the wetland vegetation cover in Kanyabaha wetland had significantly diminished. Land use and
land cover analysis showed that papyrus was the dominant vegetation but its cover decreased from
51.5% in 1990 to 39.1%, (P<0.05; R2=0.757) in 2021. During the same period, grassland cover
decreased from 34.2% in 1990 to 9.5% (P<0.05; R2=0.893) in 2021. Tree plantations, built-up areas
and bare ground expanded significantly during the 30-year period. Soil carbon density varied with soil
depth and across land cover types. Woodlands had the highest mean soil carbon density (530.2±205.5
tons/ha), followed by built-up area (107.7±28.8 tons/ha) and then tree plantations (98.3±12.5 tons/ha).
The least mean soil carbon density was observed in grasslands (45.5±3.7 tons/ha). The local
community depended on wetlands for water, crop farming, harvesting of wetland plants and grazing
their livestock. Eucalyptus trees had the highest total carbon stock (372.5±81.1 tons). Statistical
analysis confirmed the relationship between livelihood activities and carbon stocks (F= 5.02, DF = (1,
4), P<0.05). The results for species diversity revealed a statistically significant effect of site on
diversity (F₍₅, ₁₁₄₎ = 12.88, p < 0.0001), indicating that the diversity index varied meaningfully between
sites. The key drivers of wetland utilisation were low income (65.8%), demand for farmland and
settlements (8.2%), inadequate enforcement of existing wetland conservation and management
regulations (10.8%) and community limited knowledge of the law and poor farming practices (4.5%).
The adaptive strategies included diversified livelihoods (16.1%), climate-resilient agriculture (20.7%),
rainwater harvesting and storage (12.5%), agroforestry (10.3%), strengthened social networks
(18.3%), efforts to access climate information (13.3%), as well as wetland conservation (8.7%)
initiatives. The study recommended that drivers of wetland biodiversity loss be addressed by
sensitizing communities on the significance of wetland conservation, and promoting climate smart agriculture.
Additionally, comparative research on season variations in carbon dynamics in relation to land use and
climate variability was recommended.
Description
A Research Thesis Submitted in Fulfillment of the Requirements for the Degree of Doctor of Philosophy(Climate Change and Sustainability) in the School of
Agriculture and Environmental Sciences, Kenyatta University. October 2025
supervisors
Cecilia Gichuki
John Muriuki
Pantaleon M.B. Kasoma