Forest Cover Change and Carbon Stock Dynamics in Dry Afromontane Forest of Ethiopia.

Abstract

Forest ecosystems are the main wellsprings of livelihoods for many people and play a key part in regulating climate change by capturing and sequestering carbon. However, forests have been altered and converted into other land uses and thus negatively impacting land cover systems. The change in forest cover affects man y ecological, social and economic well-being. This study aimed at quantifying the effects of forest cover change on carbon stocks and ecosystem services values in the dry Afromontane forest area in northern Ethiopia. Forest cover changes were analyzed using Landsat images of 1985, 2000 and 2016. Vegetation parameters, litter and soil samples were collected from the field to quantify the carbon stock potential of the forest. Total area coverage of each land cover class was multiplied by the carbon on hectare basis of each land cover to quantify the change in carbon stock due to land cover change. Changes in ecosystem service values were estimated using land cover data of the year 1985, 2000 and 20 16 with their ecosystem service value coefficients derived from ecosystem service database of The Economics of Ecosystem and Biodiversity. Household interviews and focus group discussions were used to assess community perceptions of forest cover change and its drivers. Results from the study indicated that the dense forests and open forests increased by 8.2% and 32.3% respectively between 1985 and 2000 while it decreased by 10.4% and 9.8% respectively from 2000 to 2016. Grasslands and cultivated land decreased between 1985 and 2000 by 37.3% and 5.5% but increased between 2000 and 2016 by 89.5% and 28.5% respectively. The study further showed that fuelwood collection, cultivated land expansion, population growth, free grazing and drought were the major drivers of land cover change in the study area. Soil erosion, reduction in pollinating agent like honey bee due to a reduction in flower production, flooding and drought were the perceived major impacts of forest cover changes. Possible solutions to the current state of deforestation as indicated by respondents include strengthening of forest protection and monitoring-systems, improving soil and water conservation mechanisms, enhancing afforestation, creating awareness about the importance of forest ecosystems and zero grazing campaigns. The estimated mean total carbon stock was 181.78±27.06 Mg ha-' in- the dense forest and 104.83±12.35 Mg ha-' in the open forest. The carbon stock for grassland, cultivated land and bare land were 108.77±6.77 Mg ha-', 76.54±7.84 Mg ha-' and 83. l l±8.53 Mg ha-' respectively. Soil organic carbon and above ground carbon stock contributed more to total carbon stocks across the land cover types compared to below ground carbon and litter carbon. There was a marginal increase in carbon stock between 1985 and 2000 while carbon stock between 2000 and 20 16 marginally decreased. There was a significant relationship between above ground vegetation properties and soil organic carbon (adj. R2 = 0.59, P = 0.003). The estimated total values of ecosystem services for the study area was US$ 16.6, 19 and 18.1 million in 1985,2000 and 20 16, respectively. Generally, the study revealed that forest cover change substantially affected carbon stock and ecosystem service values in Wujig Mahgo Waren forest in northern Ethiopia. The study, therefore, recommends that enhanced efforts at conserving the forest ecosystem by all stakeholders to ensure an improved forest structure and increased ecosystem services delivery be pursued.