ForestFilter
September 14, 2008 6:00 PM   Subscribe

 
The Secret Life of Leaves.
posted by homunculus at 6:01 PM on September 14, 2008


Wait, I thought it was already conventional wisdom that old growth forests are carbon sinks.
posted by Pope Guilty at 6:09 PM on September 14, 2008 [2 favorites]


PG,

It's an election year, so all we really know for sure is that Jesus made 'em.
posted by jimmythefish at 6:21 PM on September 14, 2008


The new analysis seems to imply that the conventional wisdom is that: Old growth forests had beencarbon sinks, and removing them would toss a lot of carbon into the atmosphere, but their current carbon absorption is negligible. Apparently it turns out there's a lot less diminishing returns than was accounted for.

So not earth-shattering discovery, but good to know. Plus, OGFs are more fun to hike in.
posted by Lemurrhea at 6:26 PM on September 14, 2008


Plants consume carbon dioxide and emit oxygen, presumably doing something or other with the carbon that involves perhaps not venting it into the atmosphere. Trees are large plants. Old growth forests are comprised of large trees. How in the world did "conventional wisdom" say otherwise for any length of time beyond, say, how long it takes to get to fourth grade science class?

Let's have a look!

"That perspective was largely based on findings of a single study from the late 1960s which had become accepted theory..."

How do you kids say it in your Internet talking? "LOLWUT?" Is that right?

Can anyone smarter than I am turn up said "single study?" I'd be interested in knowing how it came to be accepted theory when its so blatantly counterintuitive.
posted by majick at 6:30 PM on September 14, 2008 [1 favorite]


Plants consume carbon dioxide while growing and release it when decaying. That at least was the conventional wisdom that you could replace old slow growing plants with new younger fast growing plants and have a net carbon sequestration gain. A lot of forestry theory is based on the notion that continual removal of older tress is healthy for forests. So, while the new study is interesting, I don't think that entire ecosystems are simple enough that we should be surprised we were mistaken about them before.

As to the lack of further studies, primary science on anything not directly medically or militarily related tends be scant. E.g. buildings consume half of all the energy used in our country and you'd be shocked how little science is applied to understanding how they work.
posted by meinvt at 6:43 PM on September 14, 2008


It seems counterintuitive because the wisdom was that trees primarily sequester carbon into their bulk whilst growing; old-growth forests aren't so much adding bulk as maintaining themselves, therefore their carbon uptake is minimal compared to actively-growing new growth timber.

Which, as any plant biologist or ecologist educated in the last 20 years would have told you, is pretty much BS. Addition of bulk in woody plants does slow down once they reach their optimal size, but not as much as you'd suspect - what would have gone into upward growth turns to canopy growth (which in turn cycles relatively quickly into soil carbon when leaves/branches are shed), girth increase (which, if you remember your primary school maths and the relationship between area and circumference, shouldn't be too much of a surprise), and associated biogenic factors (i.e. increase in soil microbial activity).
posted by Pinback at 6:52 PM on September 14, 2008


Yes, majick, I believe LOLWUT is correct. LOLWUT indeed.

I was going to say you could ask Chris Anderson... but upon checking, I see he actually cited an AskMe thread as his reference.
posted by finite at 7:08 PM on September 14, 2008


"Valuable" and "best" are not synonyms. Much the same as "valuable" and "useful" are not antonyms.

That said, I love camping in the woods. And I'd like to see them preserved.

Switchgrass mountain, seeded and harvested for CO2 sequestration, has no appeal to me as a place to camp.
posted by vapidave at 7:24 PM on September 14, 2008


I'd be interested in knowing how it came to be accepted theory when its so blatantly counterintuitive.

Easy button: Newer is always better.
posted by clearly at 7:47 PM on September 14, 2008


According to the Nature paper, the 'wisdom' was promulgated by
Odum, E. P. The strategy of ecosystem development. Science 164, 262–270 (1969)
based on 10 years of data at one site reported by Kira, T. & Sihdei, T. Primary production and turnover of organic matter in different forest ecosystems of the western pacific. Jpn. J. Ecol. 17, 70–87 (1967).

posted by lukemeister at 7:53 PM on September 14, 2008


WELL, I, as a simple BRITISH COLUMBIAN, WONDER, why these LIBERULS, seek to TAKE AWAY our WAY OF LIFE! THESE TREES...These trees, represent a LIVELIHOOD, for simple men and women who are raising children. THEN I HEAR of those...no, wait people... THOSE WHO WOULD TAKE AWAY OUR RIGHT TO CUT TREES. IN BRITISH COLUMBIA! No, no, I know, it is ludicrous but these people are OUT THERE. Well, I'm a decent, God-fearing man, but I suggest that the NEXT TIME we ENCOUNTER someone who thinks they can take away. OUR RIGHT. TO CUT TREES. We, and I'm sorry, folks, but desperate times call for desperate measures, we METE. THEM. WITH. OUR. CHAINSAWS. Cut em down, and let the Good Lord sort'em out.
posted by Turtles all the way down at 7:56 PM on September 14, 2008 [1 favorite]


Switchgrass mountain, seeded and harvested for CO2 sequestration, has no appeal to me as a place to camp.

Ah, Ol' Switchy, as we used to call it. Many a mosquito and mamba infested summer was spent there in my youth...
posted by darkstar at 8:10 PM on September 14, 2008


Over the long run, big forests are carbon-neutral. The life cycle of a forest is to grow, mature, and burn. Then the cycle starts over.

That's especially the case here in the US northwest. Fire is a normal part of the ecology here. There are plant specialists (e.g. fireweed) evolved to be early recolonizers after forest fires. And the cones from fir trees only open in high heat from a fire, so as to replant after the area burns off.

While the trees are growing, they sink carbon. When they burn, it's all released again. Cycles can be hundreds of years long, but each cycle is carbon neutral.
posted by Class Goat at 8:12 PM on September 14, 2008


Class Goat, I find it highly unlikely that natural forest fires (which are nothing like most modern forest fires) cause forests to be carbon neutral. In a healthy forest, few fires will completely obliterate the landscape.

Moreover, in the hundreds of years a particular stand of trees grows before being set aflame, much of the carbon ends up as soil.
posted by wierdo at 8:17 PM on September 14, 2008


I think the Luyssaert et al letter needs to be considered conservatively. The fact (that all foresters would acknowledge) is that all forest types are different, and it's horses for courses. Accurate accounting is very difficult in this area. I see no mention of methane, one of the main decomposition outputs and an important GHG, in those reports.


As Class Goat has already identified, in a lot of ecosystems, old growth is merely a seral stage, it's the bit of the forest that has (perhaps unusually) survived fire or human disturbance.

The real action in emissions is permanent clearing - which typically happens in the developing world under corruption, not developed world, so a naive call for an international agreement to protect these forests is more than a bit symbolic.

Also, the carbon stored in harvested wood products is not accounted for either. A full LCA would need to consider alternatives - what would displace unavailable timber?
posted by wilful at 8:44 PM on September 14, 2008


Breaking news: turns out forests are great.
posted by Rinku at 9:03 PM on September 14, 2008 [1 favorite]


Here in western North Carolina we are in the midst of several national forests. We are generally very happy people. It's the trees. How do trees get on the internet? They log in.
posted by netbros at 11:03 PM on September 14, 2008 [2 favorites]


Metafilter: we METE. THEM. WITH. OUR. CHAINSAWS.
posted by IvoShandor at 11:13 PM on September 14, 2008


Actually, until a few thousand years ago, devastating fires were the norm here in the Northwest. Fir trees dropped needles and branches full of pitch, and eventually something would set it off, and the whole thing would go up.

What happened a few thousand years ago here? Humans showed up. Turns out that the Indians Native Americans got in the habit of starting low level fires down at ground level every few years to clear out the brush, so that they could move around, and so that game could move around. Those fires happened often enough so that they didn't burn very hot and high and take out the big fir trees, and the junk didn't build up, and as a result big, devastating fires became far more unusual.

A lot of people don't realize that the Native Americans engaged in active management of the forests up here.

The way we can tell that the big fires were the norm before is because of evolutionary adaptations, like closed cones on fir trees. Or the fact that the bald eagle's preferred nest is in the branches of a standing dead tree in a recent fire zone. There are lots of plants and animals in this region who have evolved to take advantage of the areas left empty and open by devastating fires. For evolutionary adaptations like that to take place, big devastating fires must have been happening for millions of years in that ecological zone. (Which, I might mention, moved north and south during the ice ages as the glaciers advanced and retreated.)

Starting about 70 years ago, when the Forest Service adopted a "fight every fire as early and vigorously as possible" policy, the result has been that the junk has build up again on the forest floor. Now it's a mess nearly everywhere, which is why so many fires in the last decade or so have been so big and difficult to put out. Ironically, we have reverted to the ecological norm as it existed before the Native Americans showed up and changed everything.
posted by Class Goat at 11:50 PM on September 14, 2008




Didn't we already know that at least some forests perpetually sequester more and more carbon. If it didn't, would we find coal in the ground. Or is the coal consumed at some point, if we see to the whole life circle?

Although the science may be sound, the conclusions are not up to par.
Namely, in the last 100 000 years or so, forests have started sequester carbon by new means. It seems that a species of monkey has been taking branches and whole trunks and stored it in such ways that it doesn't decompose in the usual time frame.

An untouched forest wouldn't mean fewer houses, just houses made in a less environment friendly fashion. People failing to account for the alterative cost is why economists should make policies and not tree huggers.
posted by JeNeSaisQuoi at 8:03 AM on September 15, 2008


I could be way off here, but aren't old-growth forests not as good for animal life as new?
posted by C17H19NO3 at 9:23 AM on September 15, 2008


Really? Do we need to justify forests by creating a "use" for them? I figured they were autonomous living things, and last time I checked that was reason enough for not obliterating something.
posted by symbollocks at 9:33 AM on September 15, 2008


I figured they were autonomous living things, and last time I checked that was reason enough for not obliterating something.

*flagged as touchy-feely*
posted by lukemeister at 11:24 AM on September 15, 2008


I could be way off here, but aren't old-growth forests not as good for animal life as new?

Way off.

Most animals, most of the time, need diversity. Some will need all regrowth, some will need all old growth, many will prefer a mix/mosaic, but it's safe to say that overall in the general scheme of things, unless you're managing for a particular threatened species, more old growth at this time would be a good thing.
posted by wilful at 3:43 PM on September 15, 2008 [1 favorite]


From the "20 Visually Arresting but Threatened Forests" link:

> The North American Boreal Forest is one of the grandest forests in the world. It stretches from Alaska to the Atlantic Ocean, sweeping through Canada and parts of the United States. Unfortunately, it is threatened by none other than junk mail and catalog companies...Half of the Boreal has already been destroyed as it is transformed from tree to junk mail and displaced to the landfill.

This is so fucking unbelievably depressing I...I'm at a loss for words.
posted by The Card Cheat at 4:51 PM on September 15, 2008


The Card Cheat, you don't actually believe that quote do you? Seriously...

I have no idea how much of "The North American Boreal Forest"* was originally there versus how much is there now and how much is currently being 'lost', and I don't doubt that there are probably some inappropriate logging practices going on, but I will bet you that it was overwhelmingly lost in the past for agriculture and urban areas, and the current rate of deforestation due to forestry activities is negligible, virtually zero. Well-managed regeneration would ensure that the same species occur there and there is no loss of diversity or structural complexity due to forestry activities.

If there is actual deforestation, well that would be scandalous. But I'd require convincing...

Of course, those forests sure do face threats, due to climate change. Current threat #1 appears to be the mountain pine beetle (Dendroctonus ponderosae), but I'll bet there are more in the pipeline.

* in scare quotes because I suspect no one apart from the people in the link ever consider all those forests with their wide diversity and interruptions as one forest.
posted by wilful at 6:21 PM on September 15, 2008


Here's a 2002 National Geographic article on the Boreal Forest.
posted by homunculus at 9:28 AM on September 16, 2008








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