The size of lighting gaps occurring in forests of southern Poland showed the relation to the trees distribution. Using the Ripley's function it has been found that the random type of trees distribution in the investigated area had dominated (81% lightning gaps). Among the large sized lightning gaps 24% had the cluster character of trees distribution, probably due to trees biogroup formation in forest stand
Results of the study on infestation of co nys of Abies alba Mill. by cono- and seminiphages insects (502 in total) are given. Forty three samples of cones (646 cones in total) collected in the selected seed stands in 35 localities (the Kraków Forest Region) in 1999-2000 were tested. During the study damaging insects were represented by conophages: Barbara herrichiana Obr., Dioryctria abietella (Fabr.) and Earomyia impossibile Morge, and seminiphages Resseliella piceae Seitn. and Megastigmus suspectus Borr. The most abundant species in both years was R. piceae (280 spec. in 1999; 79 spec. in 2000). Conophages inhabitat 37.6% of all analysed cones. Resseliella piceae destroyed the most seeds, i.e. 15.6% of 12,900 analysed, in both years. The indices of cone infestation (WZS) showed distinct differences in values for both years, namely 1.56 and 0,35 respectively.