S. Gnaana
Saraswathi
(Corresponding author)
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Department of Botany, Holy
Cross College,
Tiruchirappalli - 620 002, India
e-mail:
sgsaraswathi@yahoo.co.in
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Publication Data
Paper received:
23 October 2009
Revised
received:
27 April 2010
Accepted:
11 May 2010
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Abstract
Seasonal changes in soil
respiration (SR), soil temperature (ST) and soil moisture (SM) were compared
between a barren land with no vegetation (control) and grassland dominated by
Heteropogon contortus
(L.) of a semi-arid eco-system during 2005-2006. A statistically significant
(p<0.001) seasonal change in SR was observed between the two sites. The
variation characteristics of soil CO2 efflux rates were observed
during wet periods along precipitation gradients and it was consistently
higher in grasslands than in control. A maximum soil CO2 efflux of
13.35 ? 0.33 ?mol m-2 s-1 in grassland and 7.33 ? 0.8
?mol m-2 s-1 in control was? observed during rainy season-II, i.e.,
from October to December, a minimum of 1.27 ? 0.2 ?mol m-2 s-1
in grassland and 0.67 ? 0.5 ?mol m-2 s-1 in control
during summer season, i.e., from March to June. A positive significant
relation observed between soil respiration and soil moisture (r2 above
0.8) and no significant?
relation was observed between soil CO2 efflux and
soil temperature (r2 below 0.3). In water-limited semi-arid
ecosystem, rewetting of the soil due to precipitation events triggered the
increased pulses of soil respiration especially in grassland when compared to
the barren land. The observed soil respiration rates during summer and after
the subsequent precipitation events strongly indicated that the soil
water-deficit conditions reduce the efflux both in barren land (control) and in
grassland of semi-arid eco-system.
Key
words
Semi-arid climate, Soil CO2
efflux, Soil respiration, Heteropogon contortus, Seasonal variation
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