La Vallée des Singes - Gorilla island

La Vallée des Singes, situated in Romagne, near Poitiers, is the second primate-park in Europe. This institution, situated in a 15 hectares forest, opened in july 1998 on the exemple of Apenheul (The Netherlands.) Today, it is home to 350 monkeys (30 different species) living in large island or walk-through exhibits.

The photo shows the gorilla island. Here, not fake rock or extraordinaries observatories for visitors, just a large exhibit (1 acre or 4000 m²) with lots of natural trees. Here, lives a gorilla family (10 animals) with Red-tailed monkey and guerezas.
Just perfect.

September 2007.

Looks great, apart from what looks like a porta-cabin at the back of it

From looking through all these pictures of the gorilla enclosure, it appears that they don't have the issue of the gorillas ring barking the trees.

The trees don't look hotwired, I am curious as to ow they have stopped it ?

Look at the thin tree on the far left.

I suspect some of the bigger trees may be hotwired to protect them or maybe there are so many trees they haven't bothered to attack many of them yet, but afaik this habit is universal in Gorillas in Zoos!

Your second option is the right one, already for 14 years. Also the bonobos have free access to all trees. On the chimp island the larger trees have been protected after one season, but not all trees are, so the chimps manage to climb a large part of the trees on their island. It's wonderful to see!