ИСТИНА

It was found, that the “Birch effect” estimated for Haplic Luvisols in the European south taiga subzone by means of the response of soil respiration to artificial watering after interruption of simulated droughts of varying intensity, is dependent on the presence of vegetation cover (grassland vegetation or bare arable land), and also on the duration of the dryness period, and on soil temperature at which the watering took place. Besides, the “Birch effect” was found to be the maximal after the interruption of the first “short” drought in the summer period and during the prolonged drought in the early Fall, when the soil respiration increase constituted 1.8 to 2.0 and between 2.1 and 2.3 times at the grassy and bare sites, respectively. Soil moisturizing after the 2nd short-term drought occurred at the lower temperatures, as compared to the first one (18 – 24oC and 13 – 17оС) and did not cause a surge of respiratory activity at the grassland site (absence of the “Birch effect”), whereas at the bare arable plots the rate of CO2 soil respiration flux increased by 1.6 times.