In the area of the Białowieża Forest (an extremely well-preserved forest complex in Central–Eastern Europe), despite the planted 49 conifer taxa, only jack pine and white pine show expansional tendencies. The reasons for this response can be grouped as follows: (1) climatic conditions, (2) biological properties of the plants, (3) late introduction of conifers for plantation and their small contribution among the planted species, (4) competition from the existing plant cover, and (5) the activity of herbivores and pathogens.

Nomenclature: Jack pine, Pinus banksiana Lamb., white pine, Pinus strobus L.

Additional index words: Cultivation, invasion, naturalization, Pinophyta.