Similar response of labile and resistant soil organic matter pools to changes in temperature

The effect of temperature change on decomposition of soil organic matter is an important factor when considering the effect of global warming on soil-stored carbon. It is commonly assumed that soil carbon exists as two fractions, a ‘labile’ fraction sensitive to temperature variation and a ‘resistant’ fraction insensitive to temperature. This implies that higher losses of carbon would occur from soils in forest and tundra, which have the largest store of labile organic matter, and that the effect of warming on soil organic matter decomposition may decline with time. Not so, according to an experiment on samples of forest soil. The temperature sensitivity of decomposition was not affected by soil organic matter composition, suggesting that all soil organic matter will respond similarly to global warming.