I saw this on television. The floating plastic debris and boats certainly provide a better vector for transmitting organisms across the ocean than simple logs did in the past. It is pretty serious, but I am sure that there has been some contamination from Asia into the Pacific northwest in the past from natural events. But how frequently it occurred I don't know. The species involved may have been different simply because of the difficulty in the past in making the journey on soggy logs. The invasive may have some difficulty getting started if their numbers are initially low, but with big chucks of debris crammed full of exotic organisms that might not be the situation here. It will be interesting to see what comes of it, it will almost assuredly be bad for the local endemic organisms.
There was a discussion about the effects of an ocean level canal through Panama on the biology of the reefs and coastal systems on each side of the proposed canal. The invasions would go both ways in this case. What everyone seemed to agree upon is that it would be a tumultuous effect o both ecosystems and for at least the next million years or so, greatly reduce the species diversity in both area as endemic species were replaced by invasive organisms.
This was worth posting here, even if not about trees.
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky