Surprising Carbon Loss in Arctic Tundra: Study

[Ivan Seeking]

Alaska scientists find Arctic tundra yields surprising carbon loss

...Bret-Harte, Chapin, lead author Michelle Mack of the University of Florida, Gainesville, and colleagues set out to investigate whether the commonly held assumption that a warming climate will lead to bigger plants that can store more carbon and thereby reduce atmospheric carbon dioxide was indeed a silver lining in the global warming cloud that some people had hoped for.

Apparently not.

"The broadest implication of this research is that climate warming could lead to a much greater release of carbon dioxide to the atmosphere and a greater positive feedback to further warming than we originally thought," Bret-Harte said.[continued]

http://www.eurekalert.org/pub_releases/2004-09/uoaf-asf092404.php

 

[Bystander]

---and, the conclusion of the article, "The paradigm is that decomposers (microbes) are always limited by carbon availability and almost never limited by nitrogen availability, but this project suggests that we don't understand decomposition as well as we thought we did. Better understanding of decomposition is necessary to be able to predict what will happen with climate warming in northern ecosystems."

Sounds a bit like they've discovered ensilage chemistry --- could have hit any ag extension office and saved twenty years.

 

[Ivan Seeking]

I've forwarded your comment to a couple of the authors. Maybe they will comment.

 

[Bystander]

Excellent! Here are some links that ain't going to get anyone up to speed, or even tuned into the breadth of the field as far as ensilage chemistry goes, but should serve as an introduction:
http://www.unece.org/trans/doc/1999/ac10c3/ST-SG-AC10-C3-1999-55e.pdf
http://dbkweb.ch.umist.ac.uk/Papers/applied&envirmicrobiol_march_1583.pdf
http://nobelprize.org/chemistry/laureates/1945/press.html
http://www.esaiweb.org/colloquium/johnstown/poster_abs.html

You probably ought to pass these along --- gives 'em a little feeling for where the comments arise.

 

[Ivan Seeking]

"I looked at the comments and the links posted by the commentor, and I admit that I am baffled by his point. I was expecting to see a link to a discussion of the relationship between silage decomposition rate and elemental stochiometry, but the posted links were pretty cryptic. I am sorry that I do not have more of a perspective to offer."

Michelle Mack

[I will forward the links]

 

[Bystander]

Okay, let's google "compost chemistry" since "ensilage chemistry" is too cryptic: http://compost.css.cornell.edu/chemistry.html links us to some quantitative results for C/N ratios (rather not use "stoichiometry" for something as undefined as decomposition of miscellaneous organic matter).

From Marie Gilbert's digest of the article (Ivan's link), quoting Harte, "

"What's really surprising about this result is that we didn't expect that this big loss of carbon from the soils would be stimulated by nitrogen alone. Everyone had assumed increased decomposition would be caused by increased temperatures, and the main effect of increased nitrogen would be to stimulate plant growth and store more carbon. We expected that fertilization by itself would lead to increased carbon storage." "


I realize the digest may have completely missed the point of the paper, but, the Harte quote suggests otherwise; so, again, I must point out that this appears to be a rediscovery of something that's been rather widely observed and "understood" (to one degree or another).

One can also compare the amounts of organic detritus/leaf litter on the floors of boreal forests and tropical forests and see the same result. I'd have to say decomposition processes are better understood than is suggested in the digest of this work.