In regard to Bob Brockie’s recent article in the Dominion Post (24 June 2013, page A8), here is some rationale for viewpoints about plants that some commentators have teasingly called “eco-fascism”. Instead, they are logical expressions about the conservation of New Zealand’s biota and ecosystems, including their genetic integrity.
For any effort claiming to be about ecosystem restoration, it is my opinion that local material of locally-native species should be used. We know that most New Zealand (plant) species naturally occurred in only part of New Zealand. We also know that local populations can have their own genetic characteristics.
This means that a given region of New Zealand has a set of native (plant) species, present at the time of human arrival, with each species having its own set of regionally-native genetic variation. If protecting this native variation is not a goal of ‘restoration’ efforts, then such efforts are not actually restoration but gardening. Gardening is fun and can have conservation benefits, but it shouldn’t be misrepresented as restoration. And some gardening, even if well intentioned, can have negative conservation impacts.
Example of genetic variation within a species: blog post on fierce lancewood, Pseudopanax ferox.
There’s still plenty of room for exotic species. I have just planted my own garden with a wealth of New Zealand species not native to Wellington, as well as with Australian species. I’ve done this because I like them, aesthetically; simple as that. But I’ve picked well-behaved species or, at least, species not known to spread aggressively.
It is surely ecologically irresponsible to plant exotic species known to cause problems in susceptible areas. Would you plant old man’s beard next to a forest remnant or contorta pine next to upland grassland/shrubland? I hope not, because they are demonstrably problematic. So why plant karo or (northern) houhere in Wellington? They are not native to Wellington (but to the northern North Island), and are known to spread aggressively, displacing locally-native species.
If you want a specific outcome, pick a well-behaved species. Brockie mentions feeding birds, and (exotic) gums and bottlebrushes are good for this, but don’t use coast banksia (Banksia integrifolia) which is already known to be an aggressive weed in New Zealand.
Personally, I like the majestic size of the (exotic) pines, macrocarpa, and gums of Wellington’s townbelt. These species are all reasonably well-behaved, but some more so than others. There are a few pine seedlings here and there, but all I have looked at have the three-needled clusters of Pinus radiata rather than the two-needled clusters of Pinus muricata. It seems that the latter could be used, at least in Wellington, to create a stand of ecologically-‘safe’ ornamental pines.
Brockie listed several New Zealand species not native to Wellington: pohutukawa, puriri, kauri, and rengarenga. I can’t see how they could justifiably be used in any Wellington effort claiming to be a “restoration” – they weren’t in Wellington at the time humans arrived. Kauri and rengarenga are well-behaved in gardens. Reports of ‘weedy’ (self-sown) puriri are slowly increasing, so it is worth keeping an eye on in case it does become a problematic weed. Pohutukawa regenerates abundantly around urban Wellington, with its small seeds spreading everywhere. I remove any seedlings that establish in my property before their roots can damage paths and walls. But pohutukawa is barely established in Wellington’s ‘wild’ areas; nevertheless, it has become a weed in several other countries, so it should be monitored here.
Karaka was also mentioned. It is an interesting (and challenging) case. Karaka was cultivated by Māori, and some planted groves are still evident. Many botanists believe that karaka was brought to the southern North Island and South Island from the northern North Island by Māori, but others think it was present in the south before humans arrived. Either way, it appears that karaka is spreading to sites where it did not occur previously, and it has the potential to fundamentally change the character of such sites.
We should be clear that New Zealand native species are not always ‘good’; certainly not when introduced overseas, and sometimes not even so within New Zealand.
Context is of course important in determining values. Gorse is abhorred by many farmers for smothering farmland, but it makes a wonderful nursery for regenerating native forest.
I think it is great that we debate conservation values, so Brockie’s article is welcomed. We need to be clear as a nation and as communities about what our goals are for conservation. Perhaps we decide we cannot afford to use locally-native material, but let’s debate it first. We do have a lot of urgent biodiversity issues in New Zealand, but wholesale restoration of our forests is not one of them, so there is no need to rush. Furthermore, given a chance (principally space and time), New Zealand’s forests are great at restoring themselves; they have done it at the end of each glacial period.
I fear that some of the activities currently being done in the name of conservation will be viewed in 50 years time with the same contempt (and perhaps without the frustrated understanding) that we now view the purposeful introductions of exotic plants and animals that cause us problems. For a country so concerned about genetic engineering, I’m amazed how blasé we are about undertaking enormous re-engineering of our ecosystems.