PARENT SESSION
Contributed Oral Session 8: Invertebrate Ecology: Butterflies; Soil Insects
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 518 C, Level 5, Palais des congrès de Montréal
Soil fertility and plant growth in soils from pine forests and pine plantations: Possible effect of red imported fire ants Solenopsis invicta (Buren) and Texas leafcutter ants Atta texana (Buckley).
Hooper-Bui, Linda *,1, Lafleur, Benoit2, Dash, Shawn3, Moser, John4, Mumma, Paul5, Geaghan, James6, 1 Fire Ant Entomology, Baton Rouge, Louisiana2 Researcher, Baton Rouge, Louisiana3 Ant Taxonomist, Baton Rouge, Louisiana4 Researcher, Baton Rouge, Louisiana5 Plant Pathologist, Baton Rouge, Louisiana6 Statistician, Baton Rouge, Louisiana
ABSTRACT- Through nest building and foraging activities, ants can alter physical properties and nutritional status of soils through structural modifications and nutrient accumulation. In turn, these alterations may enhance soil quality for plant growth. This study illustrates the effect of red imported fire ant, Solenopsis invicta Buren and Texas leafcutter ants, Atta texana (Buckley), activities on soil properties and the possible effects of fire ant soil modifications on plant growth. In our greenhouse study, fire ant ant activity decreased soil pH, and increased phosphorus (P+) and potassium (K+) in the soil. We collected soil from within and adjacent to randomly selected nests in two common habitats of Louisiana longleaf-pine (Pinus palustris) forests and longleaf-pine plantations. We also excavated two leafcutter ant nests and collected soil from the surface, fungus gardens, and the vertical strata. After physical and chemical properties were obtained from the soil samples, Gardenia japonicus seedlings were planted in soil excavated by fire ants to determine growth rate. In comparison to adjacent soil, ant nest soils from both habitats were lower in moisture content and bulk density and higher in NH4+. Fire ant nest soils were also higher in Ca2+, Mg2+, K+ and Na+ than in adjacent soils in longleaf-pine forests. Leafcutter ant nest soil was higher in pH, organic material, Mg2+, and K+. Analsysis of the soil nutrients at the surface indicate that some of the soil at the Atta nest surface was from more then 2.5 m below the surface. Gardenia japonicus seedlings grown in fire ant nest soil from pine forests were an average of three times taller than those grown in adjacent soil, and those from pine plantations were twice as tall as those grown in adjacent soils. Results suggest fire ants and leafcutter ants alter the physical and chemical properties of the soil. These soil modifications may favor plant growth since NH4+,a nutrient that limits growth, has been increased.
Key words: Fire Ants, Leaf-cutter Ants