Well, I used to get paid to be a pessimist, did that for over 20 years, guess it ruined my personality...

Seriously, I've been a big fan of NZ's island ecosystems (hope to go there someday) and Australia's, and it makes me wince every time I read about something introduced that becomes invasive because it has no natural enemies; whether animal or plant. Then there's the human toll. At my old house I used to be the crazy person chasing kids out of the yard (no fences) when I caught them picking ripe nightshade berries out of the quince bush. It was h*** on wheels trying to get that stuff out of there, but their little hands and arms fit between all the thorns quite easily. It boggled my mind why they'd want to eat something that smelled so awful!