Thursday, October 12, 2006

Ant Hills Come in Small, Large & Huge

An open sore on the ground. My metaphor for a large ant hill, like this one over on Sheldon near the Masonic cemetery.

I guess my reaction to ant hills is one and the same as my granddaughter's "Eeoww" to any creepy crawly thing. I'm bigger than she is. I should be ashamed.

But my reaction changes to awe when I consider the ant hills in a wash on the Hualapai Reservation discovered by my son-in-law. He said to look for the round white spots in these GoogleEarth images. The SIL added the red dots to emphasize the visible ant hills and noted that a mound had to be almost as large as a tree canopy to be seen from the air!

Remember Aesop's grasshopper and ant? This "before" (March) and "after" (late August) set of pictures surely echoes that ancient tale! The little guys have really been busy hauling those twigs out from underground!

Even the tiny ants are busy moving earth during the summer. Above, in a crosswalk downtown, and below, in my drive.

As for the role of the ant in ecology, Richard Strait, USDA NRCS soil scientist in Flagstaff, explains, "in the Desert Southwest, ants carry out several vital ecological functions. Harvester Ants, for instance, are one of the major seed dispersal agents in arid grasslands. While these ants have been shown to move about one percent of the total seed crop on a per acre basis, their overall impact, or effective dispersal, can be much greater. Harvester ants not only move seeds, but they affectively plant them by storing them in their nest chambers. Seeds that are not consumed often germinate to provide further food for the ants. Interestingly, in many cases ants do not consume these entire plants. Instead, they tend to nurture the plants as a steady and readily available food supply.

"Ants also have a large positive impact on desert soil chemical and physical properties. One species was shown to move 150 to 300 pounds of soil material to the surface with every new nest they build. This mixing of soil material tends to increase soil porosity and water infiltration. In addition, the mixing cycles soil nutrients and organic matter from deeper areas to the surface, thus having a large impact on the overall fertility of the soil. Numerous studies have show that the soil around ant colonies tends to be higher in organic matter, nitrogen, phosphorus, potassium and water content than adjacent soils."

As for what the ants are excavating down under when they move those big loads of soil, take a look above. To get the model, Florida State University biologist Walter R. Tschinkel poured orthidontal plaster into a large harvester ant's nest and then removed the cast. For the original, go here; the full paper is here.

1 comment:

Bea L. said...

I don't like to put poison on ant hills because of the outdoor cats. One time I tried orange peel crunched up in a blender. Didn't really work. Several martyr ants were volunteered the duty of removing the little pieces of peel -- and life went on as usual.

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