Wpływ warunków świetlnych panujących pod okapem drzewostanu na wielkość osobnika jeżyny gruczołowatej (Rubus hirtus Waldst. i Kit. agg.)

The objective of the study was to determine the effect of the forest floor light conditions on the size of blackberries. The research was conducted in the Forest Experimental Station (LZD) in Krynica (49°26'N, 20°52'E). In autumn 1999, 30 individuals were collected from two selected blackberry patches. The crown closure over the blackberry patch situated in the stand with a broken canopy accounted for 21%, while that over the patch located in the stand with the full canopy cover – 3%. The average weight of individuals from the patch beneath the dense canopy was 1.937 ±1.364 g, while individuals growing under a more open canopy were ten times greater and amounted to 18.027 ±11.993 g. The average length of shoots of individuals growing under the dense canopy was five times larger and equalled 42.4 ±35.2 cm and 278.7 ±186.7 cm, respectively. Blackberries growing under a more open canopy established every second shoot (47%) with a length exceeding 50 cm potentially capable of producing roots and thereby progeny ramets. Only one in ten shoots (13%) in individuals growing under the dense canopy was longer than 50 cm. Individuals growing under a more open canopy were several times larger, which means that the blackberry positively responded to the increased access to light by increasing the size of individuals. However, a large share of live shoot lengths in the total length of an individual from the patch under a more open stand canopy compared to the share of this parameter in the total length of an individual growing under the dense canopy suggests that under favourable conditions the expansion of this species is highly probable.