Abstract
Tropical forests can make a significant contribution to both mitigation and adaptation strategies of climate change. An effective climate change response requires consideration of the role and potential impacts on, biodiversity and ecosystem services. Several studies indicate that there is a decline in species richness along with altitude and it has an influence on biomass and soil organic carbon. Thus, this study was conducted to evaluate the impact of Elevation on Woody species diversity and carbon stock potential in Kalla forest, Konso zone, Sothern Ethiopia.
The study was conducted along three elevation gradients, namely, low elevation (1605-1690 m), middle (1691-1775m), and high (1776-1860m). A total of 60 sample plots (20mx20m) were systematically laid down at an interval of 200m between transects and 50m between plots. In each main plot, a 5 nested subplots (four from corners and one at the center) with 4 m x 4 m were used to collect sapling and seedlings. Moreover, 1 m x 1 m subplots were used to collect litter and soil. A total of 120 soil samples for soil chemical analysis and 120 samples for bulk density determination were taken separately. A total of 22 woody species, belonging to 19 genera and 14 families were recorded. Of all woody species 10, 13, and 17 species were recorded in the high elevation (HE), middle elevation (ME ), and low elevation (LE), respectively. Abundance, species richness, Shannon diversity index, Simpson diversity index, basal area, and stem density were significantly higher in the LE than ME and HE. The average woody species stem density and basal area of LE were 76 ± 38stems ha-1 and 156.0 ± 90.9m2 ha-1, which is 1.5 and 1.7,1.2 and 1.4 times higher than that of the HE and ME respectively. The Shannon and Simpson diversity indices per plot were 1.62±0.2 and 0.76±0.06 in LE, 1.29±0.4 and 0.6±0.16 in ME whereas in HE 1.55±0.2and 0.73±0.11, respectively. Juniperes Procera, Euphorbia tirucalli and Acacia Senegal were the most abundant woody species in the LE while Euphorbia tirucalli, Acokaathera schimpori and Juniperes Procera were in the ME and Euclea racemosa, Juniperes Procera and Acokaathera schimpori in HE. The total ecosystem carbon stocks (biomass plus soil, 0-30 cm) were significantly different (p < 0.05) between the LE, ME and HE. The LE showed higher ecosystem carbon stock (301.8 ± 171.6 t Cha-1t Cha-1) than ME (255.6±88.2) and HE (190.8± 58.2t C ha-1). The SOC stock (0 - 60 cm depth), standing biomass and litter accounted 90.8 %, 6.6 % and 2.6% in the LE whereas 93.0 %, 5.1 % and 1.9 % in the ME and. 92.1%, 6.3% and 1.6% in the HE Juniperes procera and Euphorbia tirucalli in the LE contributed about 81 % of the total biomass carbon stocks. While in the ME and HE, Euphorbia tirucalli and Juniperes procera , Euclea racemosa and Juniperes Procera were contributed 60 % and 48% of the total biomass carbon stock respectively. The total above-ground biomass carbon stocks were significantly correlated with species diversity. Finally, this study indicated that LE and ME have a better contribution to improve woody species diversity and total carbon stock of biomass and soil in Kalla forest, Sothern Ethiopia.
Keywords: Elevation range, Biomass, carbon stock, woody species diversity
