ants in the grassland
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Ants in the GrasslandAnn B. MayoUniversity of Texas–ArlingtonAmerica’s Grassland ConferenceManhattan, 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.
Fire ants (Solenopsis sp.) on an Oreo
Ants are quite fascinating and important.
Importance of Ants
• Ubiquitous • Diversity• Ecosystem engineers• Important relationships
Nest mound of the Western harvester ant
Internal nest of the Florida harvester ant
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
17 Study Sites
• 3 wooded sites and 14 prairie sitesNatural 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
Study Sites
burned site
oak woodland
mowed/disturbance site
mowed/disturbance site
mowed/disturbance site
Aquilla prairie
Aquilla prairie
Aquilla prairie Aledo clay loam
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
Results: PCA
• Environmental variables
*** Summary of PCA for Environmental Variables ****Axes 1 2 3 4 Total
varianceEigenvalues 0.402 0.331 0.142 0.050 1.000Cumulative percentage variance of site data
40.2 73.3 87.5 92.5
Sum of all eigenvalues 1.000
PCA: Ecological Units
Aquilla prairie
Aquilla woodland
other sites
other sites
Results: RDA• Species occurrence and environmental variables
**** Summary of Full RDA with interaction term ****Axes 1 2 3 4 Total variance
Eigenvalues 0.158 0.120 0.100 0.084 1.000
Species-environment correlations 0.936 0.971 0.978 0.921
Cumulative percentage variance of species data
15.8 27.8 37.8 46.2
Cumulative percentage variance of species-environment relation
22.1 38.9 52.9 64.7
Sum of all eigenvalues 1.000Sum of all canonical eigenvalues 0.715
Significance of Effects SummaryMarginal EffectsVariable Lambda 1LiC*DRN 0.13LiCov 0.12DRN 0.12
Conditional EffectsVariable Lambda A P FLiC*DRN 0.13 0.001 2.17DRN 0.11 0.005 2.00LiCov 0.06 0.331 1.11
RDA: Sites and Variables
RDA: Species Occurrence
RDA: Species and Sites
Functional Groups• Dominant
Forelius (2)• Camponotini
Camponotus (2)• Hot Climate Specialists
Pogonomyrmex (2)Solenopsis (2 fire ants)
• Cold Climate SpecialistsPrenolepis (1)
• Cryptic SpeciesBrachymyrmex (2)Solenopsis (2 thief ants)Strumigenys (3)
• Opportunistic SpeciesAphaenogaster (2)Dorymyrmex (2)Nylanderia (2)
• Generalized MyrmicinaeCrematogaster (2)Formica (pallidefulva group - 1)Monomorium (1)Pheidole (4)Temnothorax (2)
• Specialist Predators -- none • Tropical Climate Specialists
Labidus (1)Trachymyrmex (2)
the Comanche harvester antharassed by Forelius
Functional Groups: site evaluation
Dom Camp Hot Cold Trop Opp GM Cryp0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
Frequency of Ant Functional Groups
Aquilla PrairieAquilla WoodlandOther
Functional Group
Freq
uenc
y
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
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
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.
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.
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.