Diversity and abundance of understorey plants on active and abandoned nests of leaf-cutting ants (Atta cephalotes) in a Costa Rican rain forest
MARIANA GARRETTSON a1 , J. F. STETZEL a1 , BEN S. HALPERN a1 , DAVID J. HEARN a1 , BRENDAN T. LUCEY a1 and MARK J. McKONE a1 c1
a1 Department of Biology, Carleton College, Northfield, Minnesota 55075, USA
Nests of leaf-cutting ants (Hymenoptera: Formicidae: Attini) are abundant disturbances in Neotropical rain forests, and could affect the plant community both while the nests are active and after they are abandoned. We measured the diversity and abundance of understorey plants (>1 m in height) in the area around active and abandoned nests of leaf-cutting ants (Atta cephalotes) at the La Selva Biological Station in Costa Rica. Sampel quadrats on active nests had reduced diversity (number of morphospecies) and abundance of both small (height >10 cm) and large (10 cm–1 m) understorey plants, when compared to the nearby forest floor (3 and 13 m from the nest edge). Abandoned nests had greater diversity and marginally greater abundance of small understorey plants relative to nearby forest; there was no difference in diversity or abundance of large understorey plants. Leaf-cutting ant nests create gaps in the plant understorey when active, but serve as centres of recruitment for small plants after they are abandoned. Thus, like canopy gaps, ant nests could play an important role in recruitment of new individuals and maintenance of plant species diversity in tropical forests.(Accepted July 20 1997)
Key Words: ant nest; Atta cephalotes; Costa Rican rain forest; disturbance; gap; insect herbivory; leaf-cutting ants; plant species diversity; seedling recruitment; understorey vegetation.
c1 Author for correspondence; e-mail: firstname.lastname@example.org