Effect of fire on ground beetles and ant assemblages along an environmental gradient in NW Patagonia: does habitat structure matter? Ecoscience 13: 360-371.

SACKMANN; FARJI-BRENER, ALEJANDRO GUSTAVO

ECOSCIENCE (SAINTE-FOY)

UNIVERSITE LAVAL

Año: 2006 vol. 13 p. 360 - 371

1195-6860

The response of beetle and ant assemblages to fire (2-5 years old) and its dependence on habitat structural complexity was analyzed. Using pitfall traps, beetles (Coleoptera) and ants (Formicidae) were sampled in replicated forest, scrub and steppe areas including paired unburnt and burnt plots. A total of 176 species/morphospecies of beetles (8245 individuals) and 22 species of ants (115056 individuals) were captured. Forty-seven percent of beetle species where more frequently captured in the forest, 39% in the scrub and 24% in the steppe. In contrast, 35% of the ant species were more frequently captured in the forest, 30% in the scrub, and 45% in the steppe. Beetle abundance was the same in unburnt and burnt plots in the three habitats, but ant abundance was higher in burnt than in unburnt plots. Past fires negatively affected species richness of both taxa but the strength of this effect depends on the habitat type. Coleoptera richness was lower in burnt than in unburnt plots in the forest and steppe but was the same in unburnt and burnt scrub plots. Ant richness was lower in burnt forest and scrub plots and was similar in burnt and unburnt steppe plots. For both taxa, species composition of the forest assemblages was different between unburnt and burnt forest plots (difference almost significant for ants) but not between unburnt and burnt steppe plots. Beetle species composition in the scrub was different between unburnt and burnt plots, but ant species composition was the same. Our results support the idea that the consequences of fire on native beetle and ant assemblages depend on the habitat type but also on the regional context of the fauna. In particular, the assemblages’ pre-disturbance distribution along the environmental gradient and the way that the different habitats are used by ants and coleopteran will determine the ability of the species to deal with post-disturbance conditions.