Replacements for ash trees will depend on site specifics, say researchers

Without intervention, larger stands of ash are likely to be succeeded by sycamore and beech. For this reason, "Native woodland policy regarding sycamore and beech may need to be reviewed in UK-designated woodlands where these species are considered non-native," the authors suggest.

Assessing 27 candidate species for replacement, they conclude: "There is no single species that can substitute for the wide range of site conditions associated with the good growth of ash."

With each, "constraints in their use such as lack of silvicultural knowledge, the need for careful site matching and a supply of suitable material from nurseries all need to be considered", they advise, adding: "Where conservation of biodiversity is a priority objective, we recommend site-native species."

In Germany, felled ash has been replaced by pedunculate oak on wetter sites and black walnut on freely draining deep soils; sometimes mixed on drier sites with small-leaved lime and hornbeam, as well as Norway maple, Norway spruce and beech, they note.

However, comparison with such countries hit earlier by ash dieback "suggests that we may be too pessimistic about the lack of ash regeneration survival", they add.

The research is published in the journal Forestry.