Carbon Stock Changes Following Variation in Vegetation Types and Elevation in Jorgo-Wato Natural Forest, West Ethiopia

Abstract

Forests play an important role in mitigating climate change by sequestering carbon from the atmosphere. Although Ethiopia is one of the most biodiverse countries in the world, there are limited forest resources distributed in certain areas of the territory. The moist evergreen Afromontane forests of western Ethiopia are among the forests in Ethiopia that are contributing significantly to climate change mitigation. Jorgo Wato Forest is one of the moist Afromontane forests in western Ethiopia that help mitigate climate change. However, no studies have been conducted on the carbon storage potential of forests. Therefore, this study was conducted to assess carbon storage in different vegetation types and elevational gradients. Forest was classified into three vegetation categories including Tree-grassland (TGL), High-Forest (HF), and Dense Woodland (DWL). The elevational gradient of each vegetation type was divided into three from the bottom to the top of the forest. For each vegetation type, three parallel transect lines were constructed vertically along the elevation gradient. A total of 36 nested quadrats of 20 m x 20 m and 1 m x 1 m subplots were created following the elevation gradient along the transect line to assess tree parameters, soil samples, seedlings, and leaf litter. A total of 108 composite soil samples were collected from two depths (0–15 cm and 15–30 cm) to measure soil organic carbon (SOC). A total of 39 woody species that belong to 35 genera and 30 families were identified in the forest. The mean total carbon densities in Tree Grassland (TGL), High Forest (HF) and Dense Wood Land (DWL) were 405.049 ± 97.98t/ha,544.663 ± 208.06t/ha and 393.308 ± 147.125t/ha respectively. The overall mean stem density/ha were 1087.5. The mean total carbon stock density of Jorgo Wato forest was 447.67 t/ha with equivalent to emission of 1642.95 of CO2 t/ha. The mean carbon pools of the forest were 236.213 t/ha, 63.68 t/ha, 13.979 t/ha, 1.34 t/ha and 132.45t/ha in aboveground carbon, below ground carbon, dead wood carbon, Litter carbon and soil organic carbon (SOC) respectively. Some carbon pools showed significant differences (p < 0.05) between vegetation types and elevation ranges, while others showed no difference. The study results revealed that the forest had a potential of carbon storage, contributing to climate change mitigation. The total carbon storage densities were found to be significantly different among vegetation types and altitude ranges. Therefore, the best way and design to protect forest regarding natural vegetation categories need to be applied to enhance and expand the benefits of ecosystem services, mainly the potential of carbon storage in climate change mitigation.