THE IMPORTANCE OF WOODY PLANT INTRODUCTION FOR FOREST TREES IMPROVEMENT
The history of woody plant introduction is closely linked with that of transportationand the European exploration of the planet (16th–19th centuries). Each colonialpower established major botanical gardens and experimental stations in variousparts of the world. By the 20th century, the purpose of introductions shifted fromfood plants to timber and other species yielding non-agricultural products. Finally,during the latter part of the 20th century the importance of ornamental speciesincreased dramatically, especially to the more developed and wealthier regions.Over the past two centuries many species have started to spread in their introducedranges. Until relatively recently the majority of introduced woody species havebeen highly beneficial, if not essential, to humanity’s development, but now everincreasingnumbers of species are becoming detrimental to the maintenance of theearth’s biodiversity and to the well-being of human societies. Throughout the 19thand specially in 20th century the large-scale planting of trees for timber productionhas been one of the main reasons for the introductions of a large number of species,especially conifers e.g. Pinus, Picea. Pseudotsuga and Poplars and Willowsspecies. By using methods of mass and individual selection and by establishing ofprovenances tests, as well as by half and full sib lines of selected exotics test trees,genetical potential productivity and adaptability of introduced species have beentested in numerous experimental plots in areas where introduced have been done.This paper attempts to unravel the relationships between humans and woody plantsby looking at the changes in the introduction of species, the way they are perceivedby different human groups and the impact these non native species have on foresttrees improvement and other human activities.