Abstract: Aiming to determine the change pattern of early frost in gaps of secondary forest ecosystem in montane zone of eastern Liaoning Province, the spatiotemporal distribution characteristics of the minimum temperature in forest gaps during autumn at different slope aspects were analyzed in this study. The results showed that there was a significant difference in the minimum temperature among gaps at three slopes (P<0.01). The highest values of minimum temperature occurred at the northeast slope in September (-4.61 ℃) and the highest values occurred at the northwest slope in October (-7.24 ℃). No significant difference was found in the minimum soil temperature at 5 cm depth among gaps at the three slopes (P>0.05). The lowest values of minimum soil temperature in September and October occurred in the northwest (4.87 ℃) and southeast (2.05 ℃) slope gaps, respectively. The spatial distribution of minimum air temperature in gaps and minimum soil temperature at 5 cm depth varied asymmetrically with time, and the high-value area existed at the gap edge. In early autumn (before 28 September), the minimum air temperature of the northwest slope and the northeast slope within gaps were higher than that of the southeast slope. In late autumn, however, the minimum air temperature of the northwest slope was the highest, and that of the northeast slope was the lowest. In addition, the air temperatures within gaps fell below 0 ℃ just after the early autumn, and the differences of the air temperature between different slope aspects were greater than those in the early autumn. Compared with the minimum air temperature, the minimum soil temperature was much higher, with smaller fluctuation, but their daily variation was similar. All these results indicated that the minimum air and soil temperatures within gaps varied with slope aspects, positions within gaps and time. The minimum air and soil temperatures influenced the frost dynamics and its level of damage. Thus, better understanding the spatiotemporal distribution of the minimum air and soil temperatures within gaps played a critical role in forest regeneration and succession.

Key words: temperature-shifted controlling, endive, temperature sensitive period, bolting and flowering.