Warunki termiczne powietrza na zrębie zupełnym i gnieździe

The aim of the study was to determine the spatial variation of air temperature on the clear−cut and gap as well as to compare the distribution of thermal conditions on both areas. The research was carried out in Rogów Forest Experimental Station (51.827023°N, 19.922315°E) on a clear−cut with a width of 60 m and on a gap (of an ellipsoid shape; 40×70 m). The measurements were carried out in two series: spring−summer, in the period when the height of the sun during the day conditioned inflow of direct solar radiation to any surface (May−August 2006), and autumn, when direct radiation was limited by neighboring stands (October−November 2006). Average values of air temperature on the gap in the spring−summer period differed in individual parts by 2.2°C, while on the clear−cut by 1.0°C. In the autumn, thermal diversity on both research plots was similar (0.8°C on average). The thermal diversity within the research plots was particularly marked in the case of extreme air temperature values. Differences between minimum temperature values in the spring−summer period amounted to 1.8°C on the clear−cut, and 1.3°C on the gap, while in the autumn to 1.0°C on both research plots. Higher differentiation occurred in the case of the maximum temperature: the differences in spring−summer equaled 3.1°C on the clear−cut and 8.7°C on the gap, and in the autumn 2.7 and 3.1°C, respectively. In May, three late frost days occurred on the clear−cut, while on the gap the no frost was recorded. All late frost situations occurred during radiation weather characterized by weak wind blowing across the clear−cut. The diurnal course of air temperature in the spring−summer period was dependent on the range of shadow of the position, while in the autumn these trends were similar in each position.