Evaluation of the Carbon Footprint of Bean-Staking Activities in South Western Uganda
Abstract
The increased adoption of climbing bean varieties in Uganda has led to increased demand for staking materials since these varieties can’t grow well without staking. However, limited research has been done on the environmental impact of the use of stakes for bean growing activities. In particular, there is paucity of information on the carbon footprint of bean growing activities that involve the use of staking in Uganda. This study, therefore, determined the annual material flow and carbon footprint of bean-staking activities.
Sentinel-2 satellite images for 2019, Landsat 8 images for 2013, Landsat 7 images for 2007, were derived from Google Earth Engine. Land classification was categorized into three major classes that is; forests, subsistence farmland and barren land. Via Google Earth Engine two machine learning classification models (Random Forest and Gradient Tree Boost) were trained using the collected data and accuracy obtained was above 90% thus continued to spatial analysis since the classification process was accurate. Land use land cover maps for the years 2007, 2013 and 2019 were exported to ArcGIS to determine change detection, annual flow of staking materials and to carbon InVEST model to quantify the biomass estimation and carbon footprint.
It was found that the total carbon stock decreased from 8,351,361.43 Mg of C in 2007 to 5,730,093.98 Mg of C in 2013 and then 3,734,246.88 Mg of C in 2019. The difference in total carbon was found to be 2,619,689.79 Mg of C between 2007 and 2013, 1996,839.97 Mg of C between 2013 and 2019 due to increased subsistence farmland from 19.41% in 2007 to 31.7% in 2013 and 62.63% in 2019 and reduced forests from 72.07% in 2007 to 42.8% in 2013 28.74% in 2019. The stake contribution to carbon footprint was calculated using Y =10^{-0.535+log10(BA)} …….. 3.2 as proposed by Martinez-yrizar et al.,(1992) as 2,378,441.63 Mg of CO2 (7.77%) in 2007, 4,539.956.14 Mg of CO2 (21.62%) in 2013 and 7,675,981.07 Mg of CO2 (56.1%) in 2019 thus an overall difference of 5,297,539.44 Mg of CO2 (31.31%).
Results from the study show that there is a significant contribution of bean staking activities that is about 31.31% to carbon footprint. Therefore, proper land use management strategies within the umbrella of forests and environmental plans need to be established soon.