Constantly grazed land had a average of 1 colony/730 m2 while ungrazed land averaged 4 colonies/730 m2 and there was a significant difference in the frequency of harvester ant colonies between the 2 grazing regimes, P = 0.003, single tailed t-test. Since soil type also varies across the estate the number of colonies by soil type was also tested. Forest-Pinleno association is found on the west side of the estate while Eba very gravelly loam predominates the eastern portion of the estate. There was no significant difference in harvester ant colony density between these 2 soil types, P = 0.12, single tailed t-test. This suggests that soil composition, and secondarily plant species diversity, are not a major contributor to harvester ant colony frequencies on the estate in the semi-arid southwest, but rather the frequency of grazing (constantly grazed versus ungrazed land) is the more important determinant of harvester ant colony frequency in and around the estate.
Frequency of harvester ant nest colonies. |
Soil map of the Painted Pony Resort. |
Love the scientific inquiry you are bring to the management of the Painted Pony. Harvester ants also play a key role in soil microbiology by clipping the roots of mycorrhizae infected pecies and bring the roots (w/ fungal spores and fragments) back to the mound. This concentrated source of mycorrhizal inoculum can be 'mined' out of the mounds and used to promote plant-fungal symbiosis in other places (container plants, barren areas, etc.). Here's a good reference: http://www.jstor.org/discover/10.2307/2389862?uid=3739816&uid=2&uid=4&uid=3739256&sid=21104345431691.
ReplyDeleteKeep up the good work!!!
Thanks. it will be especially useful in the topsoil restoration barriers I have been building around the estate in an attempt to increase the ground cover.
ReplyDeleteHoward T was going to ask you for photos so I guess I failed to give him the correct link.
ReplyDeleteNo, he got the correct link. He emailed me and said the nest profile in the earlier post was more likely a leaf cutter ant nest. I changed the captions in the post and removed the harvester ant ID but left the images since the idea was to show how much soil the ants sample while building a nest making them ideal in a search for indicator minerals.
ReplyDeleteHe wrote up the "Slave Ant" article that I think was in AZ Highways among other places. The SWRS' kids were funny in the July 4 parade being ants with slave ants [dog collar around neck]
ReplyDeleteHe is definitely "the ant man" among other titles!
Your quite right, he certainly adds much to the community.
ReplyDelete