[Joanna Savage]

Two nights ago there was a porcupine break-in through the perimeter fence. I had become blase, thinking I had outwitted them as it must be a year since the last time they dug in under the fence.
The remarkable thing is that they went straight to the base of the olives and dug into the spaces created by the uneven base. Fortunately they were not deflected by rhizomatous iris or crocus, usual favourites.

In the past I have found oak seedlings germinating hard in against the olive trunks, and caches of olive seeds. I am guessing that squirrels or something else that can get through the wire netting, are hiding their winter food there. Or could it be insect nests which the porcupines remember? But it set me thinking that there is an active and particular ecological zone at the bases of the trees.

I wonder do other olive growers observe heightened biological  activity at the base of the trunks.

[Umbrian]

Bad luck Joanna, I have not noticed particular interest from porcupines, also the bane of my life, around the base of Olive trees or any other trees for that matter but they certainly have very long memories. Whenever I suffer an attack it is always in the same places even when I have given up planting their favourite plants eg iris and bulbs in particular in those spots, sometimes after several years. However I heard from a friend not far from me that, in recent weeks they have caused havoc around an isolated, old, spreading fig tree, tossing aside large stones that had been placed around the perimeter of its spread to make a feature of it. So perhaps your suggestion is correct.