How can the Caledonian Forest be restored?

This is a tricky one. The answer depends on the time frame to which you wish to restore it. Restoring the Caledonian forest of 20,000 years ago, for instance, would be impossible. There was no forest, just a massive sheet of glacial ice.

Restoring the Caledonian Forest of 1,000 years ago is more interesting, although to do so would require restoring the warmer, dryer, climate of 1,000 years ago. Since we don't know where our current climate instability will take us, this time frame is also problematic. But less so. And the inherent biological diversity of the 1,000-year ago Caledonian forest would almost certainly be more resilient. In particular, a wider variety of herbivorous, omnivorous, and carnivorous mammals might help to jump start some nutrient and other ecological cycling currently in stasis or close to it, due to the acidification and waterlogging of soils.

Currently, these cycles require large and expensive human intervention.

Wild boar, for instance, might be a more economically efficient natural plower of former forest soils than the giant Rome plows currently necessary for afforestation in the Highlands. And you can eat them.

The annual red deer hind (doe) cull that is needed to maintain grazing levels below starvation rates is also an expensive treatment. If we were "thinking like a mountain" (as Aldo Leopold said in the famous essay of that title), we might prefer to let a canine predator do the job. Here in Maine we have the coyote. In the Scotland of 1,000 years ago, and here in Maine, we used to have the gray wolf. Here in Maine, a more democratic hunting regime than is traditional in Scotland also keeps deer numbers in check. Deer are very good to eat too.

Moose are an interesting proposition. If we were "to keep all the pieces" (again, Leopold), what would their role in ecological cycles be? One possibility is that Moose, who love nothing better than a good feed of pond weed, cycle aquatic fertility back to the terrestrial system. This is the animal equivalent of seaweed on the garden, only, again, much easier for humans. And moose are very, very good to eat.

All these are hypothetical relationships, and so a test, or series of tests, is required, using fencing, soft release, radio collars, and the like, which is what the Alladale team is trying to do. Will the result be more overall ecological productivity, and more and better deer, trees, moose, boar, and so on, not just for their own sakes but for human use?

Who knows?

It is at least a testable hypothesis, and given the ecological devastation of the Highlands, deserves a good test. The Isle of Rum has been a similar test for many years, but that fine reserve belongs to the government, through the Scottish National Heritage quango. It's much more interesting to me to see if it can be done on a private reserve.

Ah, but what might my grandfather, the Kinder Trespasser, have to say about it?

Another good question. For another day.