Species diversification – which species should we use?

Species diversification can increase resilience of British forests if diversifying species are adapted to site, genetically variable, and do not harm existing forests. Immediate increase in resilience is best achieved using native or well-established exotic species, rather than ‘alternative’ species. ‘Alternative’ species currently lack adequate information on site requirements and appropriate seed sources, and there has been little assessment of their potential for damaging existing forests through pest/pathogen transfer and invasive behaviour. Future use of ‘alternative’ species for diversification should be contingent on rigorous biological risk assessment, results from forestry scale trials, and the establishment of sustainable British seed sources.