Selection of tree species for future forestry in Scotland: nativeness, diversity and resilience

摘要

As woodland expansion remains an article of Scottish Government policy, optimum selection of tree species for diverse and resilient future forestry is an important consideration. This is particularly the case given predicted climatic change and increased incidence of pests and diseases.Current woodland creation in Scotland displays a dichotomy between (a) upland spruce plantations and (b) new native woodlands. Interpretations of native status in Scotland emphasise tree species colonising naturally, between the end of the last glaciation (~11,000 years bp) and the onset of significant human influences (>5,000 years bp). Only these species are accepted for inclusion in native woodland schemes. This despite earlier occurrence within the British Isles of a wider spectrum of tree species,including coniferous genera now regarded as introduced.This approach may restrict opportunities to enhance resilience through species diversification. Across Britain and Europe, questions are now being asked as to how resilient forest ecosystems should best be developed in the light of environmental challenges. Forest Development Types (FDTs), combining native and introduced species in mixture, offer one potential framework to address this challenge.This paper suggests that, while existing models for woodland creation in Scotland remain valid, additional models should be considered and developed. These should include (a) predominantly Scottish native woodlands with a minority component of additionaltree species, native elsewhere in the British Isles or the near Continent and (b) upland mixed woodlands utilising native and introduced tree species in more flexible combinations. Continued research into species' long-term site interactions and regeneration dynamics is essential.