A survey of ant species in three habitats at Mount St. Helens National Volcanic Monument

Mount St. Helens erupted in 1980 devastating an area directly north of the volcano now referred to as the Pumice Plain.  The Pumice Plain is a heterogeneous environment represented by areas of dense vegetation and areas of sparse vegetation.  Surrounding the Pumice Plain is the Blowdown Zone which was less impacted by the volcanic explosion, but still experienced disturbance in the form of toppled trees.  In July 2008 a survey was undertaken to investigate the recovery of ant species in three habitat types at Mount St. Helens.  The habitats included two areas on the Pumice Plain varying in vegetation density (Pumice Plain Low-Vegetation (PPLV) and Pumice Plain High-Vegetation (PPHV)) and one habitat in the Blowdown Zone (BDZ).  Ants were collected through both aspiration and pitfall trapping.  A total of 10 ant species were collected during this survey with the most species coming from the BDZ habitat and the least from the PPLV habitat.  In terms of abundance, more individual ants were collected from the BDZ and PPHV habitats than from the PPLV habitat.  Additionally, ant biodiversity was highest at the BDZ habitat than at the PPHV and PPLV habitats.  Significant positive correlations between ant community parameters and plant community parameters were also found.  Namely, ant abundance and percent ground cover by plants and ant abundance and plant richness were most strongly correlated.  Both the number of plants and the complexity of plant architecture may explain the patterns of ant recovery observed in the different habitats.  Results from this survey indicate that ants are useful indicator species when assessing the recovery of biota following natural disasters.