Hey Teddy
It seems E. gunnii and E. perriniana were planted at Stavanger Botaniske Hage by 2001, so they would be in their way to 7 years old. E. gunnii seems to have been planted by 1989 there too, but it is possibly gone (or it would be larger?).
This makes me wonder how these trees behaved along the years. Also other plantings there (E. coccifera in 1987, 1991 and 2001; E. globulus by 1992; E. subcrenulata and E. pauciflora by 2001) seems to have vanished? If the extreme minima are in that range (and it could be, given the good climate in that part of Norway), then something happened.
So, if I was around Stavangerbotanical, I would be investigating what happened to all those eucalypts and taking photos of any and then show them to us E-freaks ;)