Author(s)

Deepa Dhital^1*, Suman Prajapati^2,3, Sanu Raja Maharjan², Hiroshi Koizumi⁴

¹Nepal Academy of Science and Technology (NAST), Khumaltar, Nepal.
²Department of Environmental Science, Khwopa College, Dekocha, Nepal.
³Sanima Hydro and Engineering Pvt. Ltd., Dhumbarahi, Nepal.
⁴Faculty of Education and Integrated Arts and Sciences, Waseda University, Shinjuku, Japan.

Soil carbon dioxide emission: soil respiration is representing a major contributor of accumulating carbon dioxide in the atmosphere that aids to accelerate global warming and altering the climate. Soil temperature, soil water content, sun light and vegetation are considered most common regulators of soil respiration variations in ecosystem. The soil respiration was measured in grassland intended to examine how the soil respiration changed with varying climatic factors, for two years (2015 and 2016) in temperate grassland of Annapurna Conservation Area (ACA), Nepal. In the study, soil temperature accounted exponential function of soil respiration variation at 42.9%, 19.1% and 23.3%, and temperature sensitivity of the soil respiration (Q₁₀) obtained at 6.2, 1.4 and 1.8 in October 2015 and April 2016 and both the measurements were combined, respectively. Significant negative (R² = 0.50, p < 0.05, October 2015) and positive (R² = 0.084, p < 0.05, April 2016) exponential function of soil respiration and soil water content were determined, where high soil respiration values were always measured between 30% and 35% of the soil water content. However, linear significant relationship was determined (R² = 0.376, p < 0.05) between soil respiration and photosynthetic photon flux density (PPFD). Soil respiration value averaged in October 2015 was 357 mg CO₂ m^-2 h^-1 and in April 2016 it was 444.6 mg CO₂ m^-2 h^-1. Above- and below-ground plant biomasses were obtained at 231.1 g d w m^-2 and 1538.8 g d w m^-2 in October, and at 449.9 g d w m^-2 and 349.0 g d w m^-2 in April, respectively. This study showed variation of soil respiration in relation to the factors such as soil temperature, soil water content and photosynthetic photon flux density signifying their importance in governing ecosystem function and carbon balance of the temperate grassland ecosystem.

Soil Respiration, Soil Temperature, Soil Water Content, Photosynthetic Photon Flux Density, Temperate Grassland

Dhital, D. , Prajapati, S. , Maharjan, S. and Koizumi, H. (2019) Soil Carbon Dioxide Emission: Soil Respiration Measurement in Temperate Grassland, Nepal. Journal of Environmental Protection, 10, 289-314. doi: 10.4236/jep.2019.102017.