Ecological effects and management aspects of an exotic tree species: the case of lodgepole pine in Sweden

The North American tree Pinus contorta var, latifolia was experimentally in troduced in Sweden already in the 1920s, and has been used in Swedish fores try on a large scale since the 1970s. These plantations now cover 565,000 h a, mainly in the northern area. In this paper we summarize and discuss existing ecological knowledge of thi s species introduction. With regard to longterm sustainability we suggest m anagement means to minimize harmful effects of the introduction on ecosyste ms. These include aspects of self dispersal, pests, ecosystem and landscape structures, and also ecological processes and biodiversity. We also focus on observed and possible interactions in the ecosystems. As Pinus contorta seeds are disseminated and trees regenerated outside initial plantations, t his may have future bearings on biodiversity. We suggest a strategy which takes account of the uncertainty in predicting future ecological effects. The strategy includes areal restrictions and zon es without Pinus contorta, but also to set up a monitoring program. Observa tions of adverse effects from the plantations would then give the possibili ty to adjust P. contorta management. (C) 2001 Elsevier Science B.V. All rig hts reserved.