Simulated warming reduced greenhouse gas emissions by lowering soil moisture in a <i>Pinus tabulaeformis</i> forest of the temperate zone

The forest soil carbon represents the largest carbon pool in the terrestrial ecosystem. To clarify the effect of climate warming on the soil carbon pool of a Pinus tabulaeformis plantation in the northern temperate zone, an open-top chamber was used to study the effects of warming on soil temperature and moisture, soil enzyme activity, soil active organic carbon, and greenhouse gas emissions in different soil layers. The results showed that (1) warming increased the temperature and decreased the moisture content of the atmosphere and soil. Atmospheric temperature increased by 0.9 °C on average, and atmospheric moisture decreased by 0.05%. The average annual temperatures of the surface soil (5 cm) and deep soil (40 cm) increased by 1.18 and 0.66 °C, respectively, and soil moisture decreased by 2.55% on average. (2) Warming had no significant effect on soil active organic carbon or enzyme activity, but had a significant effect on the active organic carbon content and enzyme activity in individual soil layers in individual months. For example, warming significantly altered the soil sucrase and catalase activities in the 10–20 cm soil layer in September, and also had a significant effect on readily organic carbon content in the 10–20 cm soil layer in July. (3) The seasonal variation of soil CO 2 flux showed a unimodal pattern, peaking in July and, ranging from 116.75 to 420.45 mg·m −2 ·h −1 . Warming reduced soil CO 2 emissions from the control treatment, from 996.35 to 781.57 g·m − 2 . The soil of the P. tabulaeformis forest in Daqing Mountain is a sink of atmospheric CH 4 . The seasonal variation range is −32.34 to −76.43 µg·m −2 ·h −1 , and the flux value is at its lowest in September. Warming promoted the absorption of soil CH 4 , and the seasonal absorption values of CH 4 in the warming and control treatments were 172.03 and 136.90 mg·m −2 , respectively. Therefore, after the short-term warming treatment, the soil moisture was reduced; greenhouse gas emissions were significantly reduced, and the warming formed a negative feedback with soil greenhouse gas flux.