A Review of the Current Status and Perspectives of Exotic Conifer Plantations

Abstract

Exotic conifer tree species that exhibit more rapid growth and greater timber value than native tree species tend to be selectively grown in plantations. These exotic species are also expected better adapted to climate change. However, some exotic planted species invade neighboring stands, affecting hydrological and nutrient uptake processes among natural tree species. Countermeasures to prevent exotic tree invasion can be costly; therefore, methods for assessing the impacts of introducing exotic tree species are needed. Such methods should evaluate the effects of the water and soil use of exotic tree species, as well as their invasiveness, resilience, and resistance to herbivory. Exotic species have also been studied from the perspective of novel ecosystems. The regeneration and yield of the exotic tree Cunninghamia lanceorata, which has been selected for industrial plantations in Japan, have declined in its country of origin (China) due to allelochemical production. Since tree species in plantations vary in terms of both timber production and social benefits, the effects of these species should be carefully assessed prior to their selection for large-scale planting.