• Pro Silva forestry principles
• Pro Silva and Biodiversity
• The question of non-indigenous forest species
• Pro Silva forestry and landscape protection
• Carbon
• Proclamation of Hanover
• Declaration of Apeldoorn

The question of non-indigenous forest species

1. Basic principles
2. Basic conditions
3. Problems
4. Conditions for introduction

1. Basic principles

1. The vegetation pattern which evolved in European forests during the postglacial migration of forest species, forming the existing forest regions, is regarded as a precious natural asset, which must be maintained. It should be respected as the most important basis of all silvicultural measures.
2. Non-indigenous species (exotics) can, under some circumstances, supplement the indigenous vegetation pattern and increase the economic yield of forestry.
3. All forest species which did not previously form part of a given natural plant association and which have been introduced from distant locations must be considered as exotic species.
4. The introduction of exotic species should only be allowed after critical qualitative and quantitative tests.