Nest mounds of the granivorous harvestor ant Messor capensis, Tierberg, 1991 -2005

Data on the size and dispersion of nest mounds of the granivorous harvester ant Messor capensis, including nearest neigbour distances, nearest heuweltjies, and the number, size and seed production of plants associated with the nest mounds. Although high in most plant nutrients, soils in the Karoo are generally poor in nitrogen and water infiltrability due to the low organic matter content. The actions of any animals in this region that concentrate organic matter in patches, or contribute to the movement of organic matter underground (such as termites or ants) must influence the local distribution of moisture and plant nutrients in the soil. In the southern Karoo, harvester ants Messor capensis add seed husks and soil to their nest-mounds in layers. Each layer probably represents a brief burst of underground activity following rain, when soil is placed on the mound. This is followed by a longer period of dumping of seed husks and plant matter on the mound. Although some of the plant matter is removed by wind, enough remains to increase the organic content of the soils on the edges of harvester ant nest-mounds. It is hypothesised that soils of Messor capensis nest-mounds in the southern Karoo contain more moisture, have a higher organic matter content and an elevated nutrient status compared to surrounding areas. Note: Any publications, thesis, reports etc stemming from this data must be sent to SAEON Databank for records to be kept with the data