jimbob wrote: ↑
Mon Dec 27, 2021 10:33 pm
This popped up on my YouTube recommendations yesterday.
One thing that I found interesting was that he stated that when he started trying to restore native forest to the Banks Peninsula near Christchurch, his idea of just letting the gorse alone, was considered novel and unlikely to achieve much.
I shall never forget seeing a large advertising hoarding by the side of the road in New Zealand, somewhere north of Auckland, saying something like "J Smith and Sons, Gorsekillers". Gorse is really invasive in NZ.
It is interesting what he has achieved on the Banks Peninsular, using the gorse as a nursery plant. I was disappointed that there was no mention of possums. Possums are perhaps the worst of many problems with ecosystem destruction in NZ.
They eat animals as well as plants. At peak, there were around 60m-70m of them, though apparently control has reduced this to about a half these days. Native bush regeneration in many parts of NZ is impeded by possums. The article I linked suggested that you have keep them to about 5% of what would occur without control to allow trees to grow. Maybe they are doing that on Banks. Or does the gorse protect the seedlings from being eaten by possums?
ETA: I've just had a look at the Hinewai Reserve website and they mention "traps" so I suspect there is possum control.
You travel around the parts of the north island where there used to be great kauri
forests, and there are no kauri seedlings. There aren't even seedlings even in the few preserved areas of kauri forest. Go to Great Barrier Island where possums have been eradicated, or never came, and there are dense thickets of kauri seedlings. And loads of kakas
flying around, native parrots which are a rare sight on the mainland. Possums is the problem.
Gorse can be a problem in its native areas. I have had problems encountering impassable gorse on paths, or at least getting very badly scratched by it, in a variety of places from Portugal to Italy to Britain to Norway north of the Arctic circle. Why doesn't it have this "nursery" effect everywhere?
Let's take the example of northern Portugal. It is a place I have been to several times over 40 years. The last time I was there, gorse was a real problem following the paths described in the excellent walking book we had. It was evidently spreading. The impression I got was that it was previously held in check by goats. But the villages were being emptied, and the few old people remaining could no longer run goats to pasture. On previous trips, I had seen children keeping an eye on the goats. Will this gorse now allow the native pine forest to regenerate? Given the massive hillsides covered in non-native forest of Acacia and Eucalyptus in that part of Portugal, I suspect not. Similarly we went to São Miguel Island
in the Azores a few years ago. There is almost no native forest remaining. Rather there are massive self-seeded forests of Crytomeria japonica, Japanese cedar (actually a cypress) introduced as a good tree for timber and firewood. Unfortunately it grows too well in the Azores, and is taking over. Hillsides are also entirely covered in ginger lilies
native to the Himalayas. Some places fishpole bamboo
, a Chinese species frequently grown in gardens, is taking over.
I suspect that in Britain gorse tends to get burnt, whether to preserve pasture or grousemoor, so maybe it doesn't act as a nursery for that reason. We are also told that native forest fails to regenerate in the Scottish Highlands, and doubtless other areas, because of excessive grazing by deer. I can think particularly of some moorland areas where feral horses - Welsh mountain, Exmoor, etc - are grazed, so maybe that is an issue too in those areas. I have seen forest regenerate as a succession from thorn scrub in some places I know in southern England, especially after the 1987 storm flattened some areas. But maybe with the ever-increasing density of deer here too, that is being impeded.
The commentator on the bird book has one good point, at least. Whether it amounts to a rejection of the entire book, I don' t know. In a natural ecosystem, predators restrict the places that grazers go, and so facilitate forest regeneration that way. It's now well known that wolves have had that effect in Yellowstone, we've many of us seen the TV documentaries on that. But that's difficult where the density of humans is large. Here in the Chilterns there are now plenty of deer which once lynx would have fed on, but can lynx be tolerated in such a densely populated zone? Lynx will only take sheep when they are desperate. But even in the extensive wildernesses of Scandinavia, and the lynx are pretty thinly spread, it is enough to annoy the farmers. Scotland presents better opportunities for predator reinsertion. But it is densely populated in comparison to Scandinavia.
I would also be interested to read BoaF's thoughts.