Submitted by Anonymous on Thu, 04/18/2013 - 02:43
Forums
Carbon Balance in Warming and Drying Tundra 2013

Mr. Lane,

The name of the expedition is 'warming' and 'drying'. What would be the consequence of drying of tundra? Where would the melted water go if it were 1,000 years ago (as usual)?

Where does water go when the surface of the tundra dries?

Is the effect of vegetative growth of the tundra a 'constant' factor in providing 'heat'? Are there any 'tundra blights"? Are there any other factors that affect the low vegetation growth of a tundra that are related to the water content, other than pH of dying or drying mosses?

Good luck! and thanks!

Fri, 04/19/2013 - 08:43

Tom Lane

Thanks for the excellent questions.-At CiPEHR because the plots are being warmed by the snow buildup behind the fences we are finding the permafrost is thawing in these areas more rapidly than in the permafrost area surrounding the plots. This produces somewhat of a "swimming pool" effect (thermokarst) on a small scale. The water hasn't any place to go. When the water increases in an area this seems to effect microbial respiration which in turn shows a decrease in CO2 emissions. The increased water limits O2 access which limits those microbes undergoing aerobic respiration and increases microbial anaerobic respiration the result being a potential increase in methane emissions. One of the natural consequences of thawing permafrost is this thermokarst effect the other in sloped regions is a movement of water away from the area producing a "drying" effect. At CiPEHR the natural consequences of warming tundra area being tested. That of increased wetness and increased dryness.
-If it were 1000 years ago the liquid water would either stay put (trapped) or flow away.
-When the tundra surface drys the water has either flowed away, evaporated or frozen.
-The vegetation doesn't provide heat but it is a constant in that the same vegetation type is on both the control and warming sides of the fences.
-Regarding these last two questions...I have asked Kirsten K. Coe, the Post-Doc. CiPEHR Site Manager, who did her doctoral work with mosses to address these. I'll get back to you.
Okay...so after talking with Kirsten; Mosses effect pH by lowering it in the soils and standing water around it. Sphagnum mosses which are dominant in the tundra cause the tundra to be acidic. Acidic pH as well as cold temperatures result in low rates of productivity along with other factors, i.e. low nutrient availability because the water is frozen most of the time. Permafrost also plays a role in that roots cannot penetrate deep in the soil. Mosses are nonvascular so often they can withstand a greater range of conditions than vascular plants. They can dry out or be frozen for periods of time and still recover and be productive. They are however slow growers.
Drying mosses wouldn't change the pH of the soil but dying mosses may reduce the pH of the upper organic horizons of the soil because the tissues of moss are acidic.
Here's an excellent resource on permafrost that mentions how mosses and other tundra plants contribute towards permafrost formation and maintenance.
http://curry.eas.gatech.edu/Courses/6140/ency/Chapter11/Ency_Atmos/Perma...

Tue, 04/23/2013 - 16:22

Anonymous

Thanks for your excellent answers and for pointing the direction to find out more about the mosses. Now, I have a different question. How do the 'tar pits' as illustrated in picture books relate to mastodon bones shown in the photo about the permafrost depth relate to mosses and glacier formations?
I never really thought about these things until I heard of your expedition. I just knew that when human animals destroy tundra such as in the Arctic Wilderness Refuge in Alaska, the tundra cannot be replaced like grass plots to used to fix a problem lawn.
Thanks again and stay warm!

Tue, 04/23/2013 - 16:43

Anonymous

Hello Mr. Lane,I hadn't read the article when I asked the silly question above tar pits. I was thinking that surely oil wells were located in a different places than where your team is researching the permafrost, but I see that tar pits and layers of permafrost could probably exist in different subterranean level under the earth is the same general area.
It's amazing that there are so many large areas of permafrost over the entire earth. It makes the presence of geothermal energy that much more fascinating and how carbon dioxide levels are pertinent in carbon cycling.
Thanks again!

Wed, 04/24/2013 - 07:51

Tom Lane

Hi, regarding your comment on the previous question on travel over tundra. Yes, I agreed. The tundra ecosystem is fragile. Repeated walking in the same area, four-wheeler traffic let alone heavy equipment traffic used in oil and mineral exploration has had a devastating effect on the tundra. Precautions taken by restricting traffic to times when the ground is frozen seems to still have an impact. Elizabeth Webb the researcher I am working with mentioned that even mushing over the same trails year after year leaves an imprint you can see from the air.