The effect of warming on the CO_2 emissions of young and old organic soil from a Sitka spruce plantation

摘要

Under strictly controlled laboratory conditions we investigated the response of soil respiration to increasing temperature. Soil fractions from a Sitka spruce (Picea sitchensis (Bong.) Carr.) plantation were sampled to represent "fresh" (i.e. shallower and containing more labile substrates) and "old" (i.e. deeper and presumed to contain more recalcitrant substrates) carbon sources. The soils were incubated at temperatures between 5 -30 °C, with CO_2 efflux measured using a tunable diode laser. "Fresh" soil showed substantially higher CO_2 effluxes than "old" soil, whilst respiration from "fresh" soils was more sensitive to temperature in the range 5 -10 °C. After a prolonged (56 day) incubation at 20 °C the response of soils to increasing temperature was re-tested over the same temperature interval. The CO_2 fluxes from both "fresh" and "old" soils were lower than the initial measurements, but the sensitivity to temperature had increased in both "fresh" and "old" soils.