Saraswathi S Gnaana, Paliwal Kailash
Department of Botany, Holy Cross College, Tiruchirappalli - 620 002, India.
J Environ Biol. 2011 May;32(3):333-7.
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 effiux 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 micromol m2 s-1 in grassland and 7.33 +/- 0.8 micromol m2 s- in control was observed during rainy season-ll, i.e., from October to December, a minimum of 1.27 +/- 0.2 micromol m-2 s-1 in grassland and 0.67 +/- 0.5 micromol 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 (r2above 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.
在2005 - 2006年期间，对一个无植被的裸地（对照）和一个以半干旱生态系统的扭黄茅为主的草地之间的土壤呼吸（SR）、土壤温度（ST）和土壤湿度（SM）的季节变化进行了比较。在这两个地点之间观察到SR存在统计学上显著的（p<0.001）季节变化。在湿润期沿着降水梯度观察了土壤CO₂排放速率的变化特征，并且草地中的该速率始终高于对照。在雨季II（即10月至12月）期间，草地中土壤CO₂的最大排放量为13.35±0.33微摩尔·平方米⁻¹·秒⁻¹，对照为7.33±0.8微摩尔·平方米⁻¹·秒⁻¹；在夏季（即3月至6月）期间，草地中最小值为1.27±0.2微摩尔·平方米⁻²·秒⁻¹，对照为0.67±0.5微摩尔·平方米⁻²·秒⁻¹。观察到土壤呼吸与土壤湿度之间存在显著正相关（r²高于0.8），而土壤CO₂排放与土壤温度之间未观察到显著关系（r²低于0.3）。在水分受限的半干旱生态系统中，与裸地相比，降水事件导致的土壤再湿润引发了土壤呼吸脉冲增加，特别是在草地中。在夏季以及随后的降水事件之后观察到的土壤呼吸速率强烈表明，土壤缺水状况降低了半干旱生态系统中裸地（对照）和草地的排放。
