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Ants in the Grassland

Ants in the Grassland. Ann B. Mayo University of Texas–Arlington America’s Grassland Conference Manhattan, KS. their importance and potential as indicators of ecosystem health. Why study ants?. They bit and sting. They may be pest and invasive species. We do not invite them on picnics.

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Ants in the Grassland

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  1. Ants in the Grassland Ann B. Mayo University of Texas–Arlington America’s Grassland Conference Manhattan, KS their importance and potential as indicators of ecosystem health

  2. Why study ants? • They bit and sting. • They may be pest and invasive species. • We do not invite them on picnics. Ants are quite fascinating and important. Fire ants (Solenopsis sp.) on an Oreo

  3. Importance of Ants • Ubiquitous • Diversity • Ecosystem engineers • Important relationships Internal nest of the Florida harvester ant Nest mound of the Western harvester ant

  4. Potential as Bioindicators • Ecology and small scale • Ease of monitoring • Hypotheses • Ground active ant assemblage will vary (and therefore, indicate) • with habitat • with disturbance • Comparison of ant assemblages in 17 sites • Fort Worth Nature Center, Fort Worth, Texas Tree trimming and mowing in an electrical power line right of way

  5. 17 Study Sites • 3 wooded sites and 14 prairie sites Natural experiment: sites were paired • same ecological unit/soil type • burned and unburned: 2 replicates • mowed and unmowed: 3 replicates • wooded and non-wooded: 3 replicates Details of a Comanche harvester ant nest

  6. Study Sites mowed/disturbance site burned site Aquilla prairie mowed/disturbance site oak woodland Aquilla prairie Aquilla prairie mowed/disturbance site Aledo clay loam

  7. Methods • Environmental variables • soil characteristics • vegetation characteristics • ecological units • Ant collection • pitfall traps in a 3 X 5 grid • 72 hour collection per month • March – September 2012 • Ordination Analysis in CANOCO • Functional Groups

  8. Results: PCA • Environmental variables

  9. PCA: Ecological Units Aquilla prairie other sites other sites Aquilla woodland

  10. Results: RDA • Species occurrence and environmental variables

  11. Significance of Effects Summary

  12. RDA: Sites and Variables

  13. RDA: Species Occurrence

  14. RDA: Species and Sites

  15. Functional Groups • Dominant Forelius (2) • Camponotini Camponotus (2) • Hot Climate Specialists Pogonomyrmex (2) Solenopsis (2 fire ants) • Cold Climate Specialists Prenolepis (1) • Cryptic Species Brachymyrmex (2) Solenopsis (2 thief ants) Strumigenys (3) • Opportunistic Species Aphaenogaster (2) Dorymyrmex (2) Nylanderia (2) • Generalized Myrmicinae Crematogaster (2) Formica (pallidefulva group - 1) Monomorium (1) Pheidole (4) Temnothorax (2) • Specialist Predators -- none  • Tropical Climate Specialists Labidus (1) Trachymyrmex (2) the Comanche harvester ant harassed by Forelius

  16. Functional Groups: site evaluation

  17. Conclusions • Align with environmental, vegetation, and ecological characteristics. • Potential as indicators of habitat types • Potential as monitors of ecosystem health the Comanche harvester ant foraging on seeds

  18. Acknowledgements • Photo of Dr. Tschinkel (Florida State University) and nest cast used with permission • Fort Worth Nature Center and Wildlife Refuge • City of Fort Worth, Texas • Parks and Community Services Department

  19. Questions Asked • Are there implications for understanding/monitoring climate change? Yes, this is one reason for studying ants – they are thermophilic in general and some species are found only in arid grasslands and deserts. As climate changes, the ant species present are expected to change in their occurrence, distribution and range. In the past, ants present in packrat middens have been used to asses or confirm climate conditions.

  20. Questions Asked • How are nest casts made? Dr. Walter Tschinkel has especially developed techniques for making casts in wax, plaster, and aluminum. The chosen material is poured into a nest, allowed to harden, and then excavated. Visit his site at Florida State University for more information. He has several papers on nest casts and architecture.

  21. Questions Asked • What does low intensity fire mean? The prairies that were burned were controlled, low intensity burns meant to control scrubby woody growth and reduce litter. Intensity of a burn has to do with how hot and how long. These burns did not significantly effect the soil. For ants, this means that only the microclimate above ground was affected which can be a significant deterrent to ant activity and presence. I did not detect such an effect in this study.

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