Abstract: Packed soilcore incubation experiments were done to study the effects of carbon (glucose, 6.4 g C·m^-2) and nitrogen (NH₄Cl and KNO₃, 4.5 g N·m^-2) addition on nitrous oxide (N₂O) flux during thawing of frozen temperate forest soils with two moisture levels (55% and 80% WFPS, waterfilled pore space) collected from a mature broadleaf and Korean pine mixed forest (BKPF) and adjacent secondary white birch forest (WBF). The results showed that freezing stimulated N₂O fluxes from the two forest soils shortly after thawing. With increasing soil moisture, the magnitude and longevity of the flush of N₂O fluxes from the two forest soils were enhanced during the early period of thawing, which was accompanied by great NO₃^--N consumption by denitrification, especially in the WBF soil. The addition of glucose significantly increased N₂O fluxes from the two forest soils during the early period of thawing, with great consumption of NH₄⁺-N and NO₃^--N. With increasing soil moisture, the priming effect of glucose on the N₂O flux decreased in the two forest soils, which was probably related to a greater release of dissolved organic carbon (DOC) into the soils with high moisture after thawing. Under low soil moisture conditions, N₂O fluxes were subjected to the limitation of NH₄⁺-N pool in the two forest soils during thawing, indicating the relatively great nitrification potential, especially in the WBF soil. However, under high soil moisture conditions, denitrification potential became relatively high in the WBF soil and was enhanced by the addition of glucose. A stepwise regression analysis showed that 66% of the variability in the cumulative N₂O emissions from the two forest soils during thawing could be explained by the soil pH, WFPS and waterextractable DOC pool. The cumulative N₂O emissions from the two forest soils were significantly and positively correlated to the soil waterextractable dissolved organic nitrogen pool after thawing. The cumulative N₂O emission from the BKPF soil was negatively correlated to the soil microbial biomass N. From the experimental results, it can be reasonably concluded that N₂O flux during thawing of frozen temperate forest soils depends on soil pH, WFPS, and the amount of dissolved organic matter released into the soil.

Key words: grape, light-response curve, fruit quality.