Sunday, 8 January 2012

The Australian Pine

In a comment on another post my friend Mary, writing from the Bahamas, asked me to compile something about "Australian Pines".   I'm not sure how qualified I am to do this but I do have a few thoughts, observations and (as usual) opinions so here goes.  While much of what follows may be well known to readers in the Bahamas I have put in the background for the benefit of others.

Mary has posted a link to this post on her blog.   There is an interesting comment there already!

I'll begin with a clarification about my interpretation of the term "Australian Pine".  I started off with a view that this would refer to one or more Casuarina species rather than a true member of the genus Pinus.  That view largely came about from our time in Tanzania where Casuarinas were referred to as "Whistling pines" because of the romantic sound of the Trade Winds blowing through them.  My view seems to be confirmed by Googling "Bahamas Casurina" and finding it to be a topic of some controversy and debate.

The controversy is not limited to the Bahamas.  A similar debate appears to be going on in the Turks and Caicos Islands

In Tanzania the Casuarinas appeared to be growing more on Zanzibar, the smaller of the two members of the "United Republic" although we did come across them in a few beach front locations on the Mainland.  There is a paper indicating that C. equisetifolia does permit - possibly enhance -  indigenous regrowth in some areas of Zanzibar.  (That last point will be heresy, if not anathema, to the People for Botanical Purity (PBP).  Oh dear, what a pity. never mind. )   We were told by some waninichi (ie locals) that they had self-established, with the seeds floating across from Western Australia.  This is possible if the seeds managed to dodge Madagascar and could survive in salt water for  however long it takes them to float some 8,000 kilometres across the sea.
However, to get to the Bahamas the seeds would have a far longer trip and have to either:
  • dodge the whole of Africa; or 
  • pass through the Straits of Magellan!
Fortunately a helpful (albeit highly repetitive) article from the Bahamas National Trust (BNT) is explicit that "In the 1920’s when the Casuarina was introduced to The Bahamas ... ".  (A naturalist friend in Australia puts the odds as "London to a brick" that they were also introduced to Zanzibar.)  This raises the whole issue of introduced weeds and what to do about them, but before -briefly  - having a look at that I should address the issue of what uses could be made of the Casuarinas in the Bahamas and other places where they have been introduced.

A first comment is that the trees seem to be well regarded by the Real Estate mob.  My initial Google Search produced many links to places with names along the lines of  "Casuarina Bay View Resort".  So it would seem the trees have a positive view amongst the property buying classes (the realtors would probably find it more difficult to market Deadly Nightshade Condominiums).

Probably the worst thing that could be done would be to pile the chopped trees up and burn them: a default option in the ACT!

Any use that can be found for the Casuarinas would prevent some other, more desirable, tree from being felled.  I recall that in Tanzania Casuarina timber was suggested as suitable for scaffolding - for which endangered endemic mangroves were normally used.  A timber oriented paper does suggest use of Casuarina timber for pit-props (this is probably not applicable in the Bahamas - and I would certainly expect them to have OHAS issues with Casuarina scaffolding)!

More tangibly, Wikipedia is a start.  However, other than windbreaks and firewood (eg the fire under Mary's hot tub, and the barbecues mentioned in comments on the Bahamas Pundit post, linked above) the article is a tad thin on uses  of the species evident in the Bahamas.  Mention is made of its high nitrogen content so one possible use (if all else fails) is to mulch the trees when chopped down.

A further way of using the felled trees is to put them in eroded areas where they will act as seed-traps for the seeds of other plants (hopefully desirable ones) that are blowing in the wind.  This will make islands of revegetation.  It seems from a massive experiment being undertaken just North of Canberra that dumping tree trunks (felled by the land developers and road builders) will also encourage invertebrates and thus the reptiles, mammals and birds that feed on them.

Help comes (as might be expected) from Greening Australia.  In the section of the linked paper on uses of these trees they note that all species have similar characteristics so the high end uses such as furniture would seem to apply to any Casuarina species.  From discussions with the craftsman who made our furniture, it is however important, for supply to furniture makers (beyond the hobbyist level), that a good amount of high quality wood is made available to allow them to create matched sets of chairs etc.  This leads to a key point, that the use of the trees must be planned and managed.

Planning and management are also important in the removal and replacement of the trees.  While Bahamas Pundit and the BNT both seem to feel the trees encourage erosion, the timber article states that in Indonesia one species is particularly used as a beach erosion control mechanism!  (Both Bahamanian articles also mention moving a road in the case of the main grove being considered: perhaps the road and its trail bike and quadbike users is really the issue?)  I would suggest that simply whacking down the trees en masse is certainly not going to help if a hurricane arrives soon after.  A better approach would appear to be to thin the trees (perhaps taking out half in the first cycle) and for a year or two replacing them with desirable indigenous species which are allowed to grow before felling the remainder.  (On observation in the ACT such nuances appear to be beyond the capacity and skill of the planning authorities and their contractors). It is good to see that the authorities in the Turks and Caicos are offering free mahogany trees as a replacement!

It is also important that any replacement planting is maintained.  Keep the yoicks on trail bikes away, perhaps shelter the new plantings from wind and seaspray until established, suppress weeds etc.  This is a hard concept to get across to the suits controlling funds for public works who seem to feel intense pain about any expenditure which involves paying people to maintain services.

This post is written by someone who has spent a whole 104 hours in the Bahamas and is thus extremely ignorant about local conditions in that archipelago!  However the arguments that seem to be floating (or blowing) around appear similar to those used in Australia whenever a successful introduced plant is considered to be needing removal.

A first point is that there is often an element of ideology "Import=bad, indigenous=good." bubbling away beneath any science that is quoted. This tends to press my cynicism button!  In this case that debate is exemplified by one paper saying the Casuarinas encourage beach erosion while another paper cites a case of them ameliorating the erosion.  Resolving that conflict is "problem not bilong mi.".

If it is concluded that the Casuarinas are due for the ultimate bonsai treatment there are many uses, included above, to which the resultant material can be put.  That needs to be thought through and managed before the chainsaws and bulldozers move in.

In addition the way the clearing process is managed requires a little more thought than simply putting a Caterpillar D9 at one end of the affected land and a guy with a can of petrol and a box of matches at the other.  It is essential that the task in managed in such a way that there is always vegetation cover on the land.


Mary said...

Thanks, Martin.

I had thought to myself, "Why not consult a knowledgeable Australian about what Australians do with "Australian Pines"? It turns out that this resulted in some very thoughtful commentary.

What you wrote is most helpful and informative. Thank you for doing so. I plan to circulate your comments and suggestions to my friends down here who are wondering what our next steps might be. You focus on management and use rather than elimination of the tree, which makes great sense.

In the near future, I will blog a set of photos of the Australian Pines on our island for you all to see.

However, they got here, who knows? But Australians are well known for their travel, far and wide. It makes sense that their trees would follow.

Even though I had a great idea to ask you about Australian Pines, please don't ask this American what we should do about our invasive clothing or food like "American bluejeans" or "MacDonald Hamburgers" I haven't a clue.

Thanks again. I will let you know if this results in any further useful discussion.

Flabmeister said...

Thanks for that Mary. I will insert a link to your blog in my post. That way people will be able to get at the debate in both directions. Good to see one of the Bahamanians has already responded to your post.