It’s all about the variation, stupid

12 01 2015

val-1-3It is one of my long-suffering ecological quests to demonstrate to the buffoons in government and industry that you can’t simply offset deforestation by planting another forest elsewhere. While it sounds attractive, like carbon offsetting or even water neutrality, you can’t recreate a perfectly functioning, resilient native forest no matter how hard you try.

I’m not for a moment suggesting that we shouldn’t reforest much of what we’ve already cut down over the last few centuries; reforestation is an essential element of any semblance of meaningful terrestrial ecological restoration. Indeed, without a major commitment to reforestation worldwide, the extinction crisis will continue to spiral out of control.

What I am concerned about, however, is that administrators continue to push for so-called ‘biodiversity offsets’ – clearing a forest patch here for some such development, while reforesting or even afforesting another degraded patch there. However, I’ve blogged before about studies, including some of my own, showing that one simply cannot replace primary forests in terms of biodiversity and long-term carbon storage. Now we can add resilience to that list.

While I came across this paper a while ago, I’ve only found the time to blog about it now. Published in PLoS One in early December, the paper Does forest continuity enhance the resilience of trees to environmental change?1 by von Oheimb and colleagues shows clearly that German oak forests that had been untouched for over 100 years were more resilient to climate variation than forests planted since that time. I’ll let that little fact sink in for a moment …

Afforested-ContinuousWhile the researchers found that forests planted on former arable land had higher growth rates (estimated by measuring tree ring widths) than continuously existing forests due mainly to legacy effects of higher nutrient profiles and fertilisation, the variation in growth was much, much higher in the former. This means that when conditions were bad, the afforested areas succumbed more quicker and drastically than their established counterparts. The figure I modified from the authors’ original shown on the left demonstrates this better than words can describe.

While some of the statistics weren’t that flash, the result is beyond dispute. This adds a lot more weight to the argument that keeping primary forests intact is a far better strategy for ensuring the long-term resilience of biodiversity than attempting some half-arsed restoration that never quite hits the mark. The moral of the story is that we need to protect all remaining primary forest, and reforest the hell out of the vast swathes of deforested lands that now dominate our planet.

CJA Bradshaw

1Another little bugbear of mine – interrogative titles. Please, oh please, just tell us the answer and avoid patronising questions!

 


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9 responses

14 01 2015
thomasfairman

Looks like an interesting paper! Though I have to differ with you on your distaste for interrogative titles. Love a good enticing question in the title, and anyway, if it makes you download the paper and read the abstract to get the answer, then it’s all the more engaging.

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14 01 2015
CJAB

You’re entitled to your opinion, of course, but I must disagree – I find them disingenuous, patronising and a waste of time. I tend to avoid reading (and citing) papers that have interrogative titles altogether.

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14 01 2015
thomasfairman

You’re very lucky Darwin didnt name it “On The Origin Of The Species?”, then.

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15 01 2015
Mike Fowler

I’m with Corey on this one. We’re all busy – we should never assume our readers have enough time to read the Abstract before they can be enticed into reading the whole damn paper. We’re just not that important.

This is not Hollywood. Spoil the plot as soon as you can.

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13 01 2015
Moz of Yarramulla

Florian, the question is whether you regard the forest as a pure carbon sink or whether it has other values. For example, the mature forest will have more biodiversity and to some of us that has value too.

I use the “murder offset” example to counter some of this thinking. Since I sponsor a number of children through World Vision I can offset those lives saved by killing people here in Australia, right? It makes sense, that’s how “replacement planting” works. There’s even a net win, since I save more people than I kill. (if you want to shock people less you could use the SPCA “sponsor a shelter puppy” program instead, although killing dogs also offends some people).

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17 01 2015
Clem

Moz, I think you’re on the right track. The “murder offset” is over the top. Hyperbole. So back it off a touch and use the puppies example. And as you rightly note, killing dogs also offends some (though presumably fewer). So the puppy approach is a touch closer to what we want.

So if we stay on this track and back it off a smidgeon more, lets say we use “tree killing” – hmmm, this is creeping up on being an accurate portrayal. But alas, this doesn’t grab enough people. What to do? Its just a thought, but why not celebrate the fact the offset planting is a positive thing (beats doing nothing) and, as Corey has done above, continue on to make the case for even more positive endeavors.

Screaming “murder” just to get the attention is as immature as screaming ‘fire’ in a crowded theatre (when there is no fire). We can and should be better than this.

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13 01 2015
Dayna

Hi,
Its a noble and important quest you’re on. To make government and industry see reason? There are many who wish they would see beyond self interest. Thanks for the post!
Just two wee points: in the paragraph below the graphs you’ve said ‘growth rates … than’ (I’m keen to know the mising word) and just a but further on (since I’m being picky) ‘they’ should be ‘the’ before the word ‘variation’.
: )

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13 01 2015
CJAB

Thanks. Typos fixed.

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13 01 2015
Florian Hartig

Is it really that clear that it’s undesirable if a stand shows higher growth as well as more growth variation? If timber is removed, e.g. for carbon sequestration, I would probably prefer such a stand, all other things equal. Yes, one can conjecture that higher variation in growth is connected to higher vulnerability to drought, but I don’t see any direct evidence for that from this study.

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