ABSTRACT
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.