Canopy Roads of South Georgia

Pine pollen early this year?

Does it seem early to you to see this slash pine pollen cone on ground, and the thin film of yellow pine pollen on everything outside?

Picture by John S. Quarterman for Okra Paradise Farms, Lowndes County, Georgia, 30 January 2013.

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Higher climate temperatures mean more and faster tree deaths

Higher average temperatures mean much more frequent droughts and trees dying faster in droughts because of the temperatures. That plus pine beetles, according to research from 2009. Forestry is Georgia's second largest industry in terms of employment and wages and salaries, more than $28 billion a year according to the Georgia Forestry Commission, plus an estimated $36 billion a year in ecosystem services such as water filtration, carbon storage, wildlife habitat, and aesthetics, not to mention hunting and fishing. Climate change matters to Georgia's forests and to Georgia.

The paper appeared 13 April 2009 in the Proceedings of the National Academy of the Sciences, Temperature sensitivity of drought-induced tree mortality portends increased regional die-off under global-change-type drought, by Henry D. Adams, Maite Guardiola-Claramonte, Greg A. Barron-Gafford, Juan Camilo Villegas, David D. Breshears, Chris B. Zou, Peter A. Troch, and Travis E. Huxman, 106(17) 7063-7066, doi: 10.1073/pnas.0901438106.

All drought trees in the warmer treatment died before any of the drought trees in the ambient treatment (on average 18.0 vs. 25.1 weeks, P <0.01; Fig. 1A).

They say warmer trees dying faster in drought wasn't due to a difference in amount of water. Instead, they infer the warmer trees couldn't breathe.

Combined, our results provide experimental evidence that piñon pines attempted to avoid drought-induced mortality by regulating stomata and foregoing further photosynthesis but subsequently succumbed to drought due to carbon starvation, not sudden hydraulic failure. Importantly, we isolate the effect of temperature from other climate variables and biotic agents and show that the effect of warmer temperature in conjunction with drought can be substantial.

Our results imply that future warmer temperatures will not only increase background rates of tree mortality (13, 16), but also result in more frequent widespread vegetation die-off events (3, 35) through an exacerbation of metabolic stress associated with drought. With warmer temperatures, droughts of shorter duration—which occur more frequently—would be sufficient to cause widespread die-off.

How much more frequently? They calculated an estimate for that, too: five times more frequently. Of course, that's for the specific kinds of forests they were studying, and the exact number may vary, but the general trend is clear: higher temperatures mean more frequent droughts, like the year-long drought we just experienced in south Georgia.

This projection is conservative because it is based on the historical drought record and therefore does not include changes in drought frequency, which is predicted to increase concurrently with warming (2, 37—39). In addition, populations of tree pests, such as bark beetles, which are often the proximal cause of mortality in this species and others, are also expected to increase with future warming (7, 9, 38).

Bark beetles, such as the ones that bored into this 19 inch slash pine and spread from there to twenty others I had to cut down to prevent further spread of the pine beetles. What happens when pine beetles spread is what you see in the first picture in this post: acres and acres of dead red pine trees. Monoculture slash pine plantations may show this effect most clearly, but look around here, and you'll see red dead loblolly and longleaf pines, too.

The article is saying that if the beetles don't get the trees weakened by droughts that will be much more frequent, the trees will die more quickly of suffocation, because the temperature is higher. Higher temperatures is something that should concern every Georgian in our state where forestry is the second largest industry and our forests protect our wildlife and the air that we breathe and the water that we drink.

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100 foot dead tree

This tree was struck by lightning almost two years ago and then pine beetles got into it. It's been dead for more than a year, and it was leaning towards the house, so we had to take it down.

Distant
John S. Quarterman, Gretchen Quarterman, Brown Dog, Yellow Dog,
Picture by Gretchen Quarterman for Okra Paradise Farms, Lowndes County, Georgia, 18 June 2012.

Zoom:

Lightning striking a tree @ Okra Paradise Farms 3 August 2010

Gretchen went back inside after lightning struck a tree less than 100 feet from where she was taking this video two years ago. This is the tree we had to take down last week. Strike:

Strike
John S. Quarterman, Gretchen Quarterman, Brown Dog, Yellow Dog,
Pictures by Gretchen Quarterman for Okra Paradise Farms, Lowndes County, Georgia, 3 August 2010.

Streak:

Longleaf candling at the pond, Okra Paradise Farms, Lowndes County, Georgia, 22 April 2012

We didn't know there were any longleaf at the bottom of the pond, but the white candles are unmistakable:

Pictures of Longleaf pine (Pinus Palustris) by Gretchen Quarterman
for Okra Paradise Farms, Lowndes County, Georgia, 22 April 2012.

The needles are also longer than on the nearby slash pines:

Pine beetles, Okra Paradise Farms, Lowndes County, Georgia, 11 April 2012

Brown Dog and Yellow Dog in some red pine needles:

John S. Quarterman, Gretchen Quarterman, Brown Dog, Yellow Dog,
Lowndes County, Georgia, 11 April 2012.
Pictures by John S. Quarterman for Okra Paradise Farms.

And the reason why they're red:

Moon above growing pines

One day after a rain, and a few days before a full moon:

Pictures by John S. Quarterman, Lowndes County, Georgia, 8 September 2011.

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