Effect of warming on the temperature dependence of soil respiration rate in arctic, temperate and tropical soils

We examined the response of the temperature coefficient (Q₁₀) for soil respiration rate to changes in environmental temperature through a laboratory incubation experiment. Soil samples were collected from three climatic areas: arctic (Svalbard, Norway), temperate (Tsukuba, Japan) and tropical (Pasoh, Malaysia). The arctic and temperate soils were incubated at 8°C (control), 12°C (4°C warming) and 16°C (8°C warming) for 17 days. The tropical soil was incubated at 16°C (8°C cooling), 24°C (control) and 32°C (8°C warming). Before and after the incubation experiment, the temperature dependence of soil microbial respiration was measured using an open-airflow method with IRGA by changing the temperature in a water bath. The initial Q₁₀ before the incubation experiment was larger in the soils from higher latitudes: 3.4 in the arctic soil, 2.9 in the temperate soil, and 2.1 in the tropical soil. The response of the microbial respiration rate to change in temperature differed among the three soil types. The temperature dependence of respiration rate in the arctic soil did not change in response to warming by 4 and 8°C with a Q₁₀ of about 3. On the other hand, the Q₁₀ in the temperate soil decreased with increasing incubation temperature: from 2.8 in soils incubated at 8°C to 2.5 at 12°C and 2.0 at 16°C. In the tropical soil, the Q₁₀ was not changed even by the 8°C warming with a value of 2.1, whereas the Q₁₀ was increased from 2.1 to 2.7 by the 8°C cooling. These results suggest that the response of microbial respiration to climatic warming may differ between soils from different latitudes.