Carbon stock of woody species along Altitude gradient in Alemsaga Forest, South Gondar, North Western Ethiopia
Abstract
Purpose: Forest ecosystems playa significant role in the climate change mitigation and biodiversity conservation. Therefore carbon determination provide clear indications of the possibilities of promoting forest development and management for mitigating of climate change through soil and vegetation carbon sequestration. The study was carried out to quantify carbon stock potential in Alemsaga Forest, South Gondar zone.
Research method: Vegetation data Collection was made using a systematic sampling method; laying six transect lines with 500 mapart and 54 quadrants of 20 m X 20 mestablished 200 mdistant to each other along the transect lines. In these plots, abundance, DBH and heights of all woody species were recorded, and soil sample was collected 1m X1m from the four corners and center of each quadrant. General allometric model was used for estimating above and belowground biomass. The organic carbon content of the soil samples was determined in the laboratory.
Finding: A total of 66 woody plant species belong to 42 families were identified, Fabaceae was the most dominant families. The total mean above and belowground carbon stock was 216.86 ton/ha and 114.71 ton/ha respectively and soil organic carbon (SOC) 103.15 ton/ha. Above and belowground carbon increased as altitude decreased, but SOC increases with increase of altitude.
Originality/value: Carbon stock estimation in the forest helps to manage the forests sustainably from the ecological, economic and environmental points of view and opportunities for economic benefit through carbon trading to farmers. Key word: Altitude, Carbon stock, Forest, Woody species.
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Introduction
Forests provide a diversity of ecosystem services including converting carbon dioxide into oxygen and biomass, acting as a carbon sink, aiding in regulating climate, protection of hydrological services, biodiversity conservation and aesthetic values (Scherr et al., 2004). Climate change is areal recent problem that harmfully affects environmental norms and populations, causing a severe negative impact worldwide. It is supposed that the aim of decreasing carbon sources and increasing the carbon sink that can be attained through keeping and maintaining the carbon pools in existing forests is among the top priorities of climate change mitigation (Brown et al., 1996). Carbon sequestration is the removal of CO from the atmosphere 2 and storing it in the ocean, vegetation, soil and geological formation (IPCC, 2000). Forests are a current focus for action since they playa significant contribution to mitigating climate change by absorbing carbon emission from the atmosphere (IPCC, 2000).
The sequestration of carbon is one of the many ecosystem services supported by biodiversity (Maestre et al., 2012). Therefore biodiversity is very important for carbon storage to enhance nutrient availability and socioeconomic benefits (Brown, 2002). Carbon is initially sequestered through photosynthesis before being transferred to one of a number of terrestrial pools including aboveground biomass, dead wood, litter, roots and soil (Gorte, 2009). Carbon stock can be influenced by different factors, including altitude, tree species, climate, soil nutrient availability, disturbance and management regime (Houghton, 2005). Carbon stock in trees increases with temperature, nutrient availability , soil moisture and tree density, and SOC increase with precipitation, and decrease with temperature (Jobbagy and Jackson, 2000).These pools are then subject to gains and losses depending on rates of growth, mortality and decomposition that are in turn affected by varying human and natural disturbances (Maestre et al., 2012).
Alemsaga Forest is found in the western edge of the Farta district of Northern Ethiopia. The area is protected starting from 1978 with the objectives of providing seed source, maintaining the remnant natural forests and recovering the degraded area. Between 1990 and 1992, during the government transition, the area was converted into pasture and farm lands. After political stability in 1993 of the country the area was re-protected as forest area (Farta woreda agricultural office, 2017). Deforestation and grazing are ongoing challenges for conservation of study forest (Farta woreda agricultural office, 2017). Carbon determination may provide clear indications of the possibilities of promoting forest development and management for mitigating of climate change through soil and vegetation carbon sequestration. Therefore, the study was to quantify above and belowground biomass, and their carbon stock of forest, to quantify soil organic carbon stock, and to determine the variation of carbon stock along altitudinal gradient.
Conclusion
The mean above and below ground carbon stock was 91.43±70.78ton/ha and 22.86±17.69 ton/ha respectively. In general the result showed that, the lower altitude have higher carbon stock of woody species due to the presences of larger DBH trees species and favorable environmental condition such as moisture and nutrient availability. The mean SOC of the study site was 102.15± 33.62 t/ha, but the higher part of altitude contains higher amounts of carbon stocks in soil might be the contained indigenous shrubs and grass which have enough litter fall.
Forest soil was also found to be a good reservoir of carbon stock in the study forest as relative carbon stock was found. The total carbon stock in all carbon pools were 216.68 with the corresponding value of 796.74 ton/ha CO eq.Therefore, proper 2 protection and management of woody species are very important for conservation of biodiversity as well as carbon storage. Generally, the present study can contribute towards the understanding of above and below ground carbon stock, and soil organic carbon. Therefore, further studies should be conducted on soil seed bank, regeneration status and population structure is important for future restoration/rehabilitation and better conservation of forest resources in the area.
