Ghostytoasty · Today 15:53
Sycamore is a non-native species but it is not considered invasive.
Most people who are in the field think so. I have an interest, because my dad has been part of a conservation group, for over 30 years; they plant native British species in his and surrounding villages. He's a botanist and a retired agronomist / horticulturalist.
If they find sycamore (and certain other foreign species) saplings, they get rid of them, but wouldn't do so with mature trees. They did have a rhododendron infestation and they destroyed them.
https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/a-z-of-british-trees/sycamore/
The seed is extremely fertile, so sycamore has spread quickly across the UK and colonised many woodlands to the detriment of native species.
http://www.mikepalmer.co.uk/woodyplantecology/sycamore/britain.htm#:~:text=Sycamore%20invades%20different%20types%20of,despite%20a%20regular%20seed%20production.
Sycamore invades different types of woodlands in the British Isles including birch, ash, alder and oak woods and many disturbed sites. However, the speed of invasion is usually slow because the conditions suitable for sycamore regeneration only occur at irregular intervals despite a regular seed production.
https://www.woodlands.co.uk/blog/tree-identification/sycamore/
The sycamore is fast growing tree and regarded by some as a ‘weed’. It is not a native tree, it is native to central, eastern and southern Europe.
. Its heavy leaf fall can mean that the ground flora underneath the tree is limited. However, on the plus side, it offers a food source and shelter for wildlife (for example, aphids tap into the sugar rich leaves and that leave behind their sticky honeydew). The aphids are a food source for ladybirds and birds.