Effect of leaf-cutting ant nests on plant growth in an oligotrophic Amazon rain forest

Authors

Amartya K. Saha, Southeastern Environmental Research Center, Florida International UniversityFollow
Karine S. Carvalho, Departamento de Ciências Biológicas, Universidade Estadual do Sudoeste da Bahia
Leonel da S.L. Sternberg, Department of Biology, University of MiamiFollow
Paulo Moutinho, Instituto de Pesquisa Ambiental da Amazônia

Abstract

This study examined whether high nutrient concentrations associated with leaf-cutting ant nests influence plant growth and plant water relations in Amazon rain forests. Three nests of Atta cephalotes were selected along with 31 Amaioua guianensis and Protium sp. trees that were grouped into trees near and distant (>10 m) from nests. A ¹⁵N leaf-labelling experiment confirmed that trees located near nests accessed nutrients from nests. Trees near nests exhibited higher relative growth rates (based on stem diameter increases) on average compared with trees further away; however this was significant for A. guianensis (near nest 0.224 y⁻¹ and far from nest 0.036 y⁻¹) but not so for Protium sp. (0.146 y⁻¹ and 0.114 y⁻¹ respectively). Water relations were similarly species-specific; for A. guianensis, near-nest individuals showed significantly higher sap flow rates (16 vs. 5 cm h⁻¹), higher predawn/midday water potentials (−0.66 vs. −0.98 MPa) and lower foliar δ¹³C than trees further away indicating greater water uptake in proximity to the nests while the Protium sp. showed no significant difference except for carbon isotopes. This study thus shows that plant response to high nutrient concentrations in an oligotrophic ecosystem varies with species. Lower seedling abundance and species richness on nests as compared with further away suggests that while adult plants access subterranean nutrient pools, the nest surfaces themselves do not encourage plant establishment and growth.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Saha, A.K., K.S. Carvalho, P. Moutinho, L.S.L. Sternberg. 2012. Effect of leaf-cutting ant nests on plant growth in an oligotrophic Amazon rain forest. Journal of Tropical Ecology 28(3): 263-270.