A central task for resource managers is to define habitats within landscapes they manage, to estimate the value of each habitat, and to manage and restore the appropriate habitat mosaic to meet conservation goals.  In central North America, deciduous forests that dominate to the east meet grasslands that dominate to the west, producing a range of possible habitats defined by woody vegetation density.  Defining habitats along this gradient is important for setting management goals and in determining the strength of the relationship between species and habitats.  We define five habitats along this gradient and examine how strongly affiliated a variety of animal and plant species are with those habitats.  Our aim is to assess whether savannas – a habitat with characteristics intermediate along the grassland-forest gradient – possess a unique flora and fauna or are more aptly described as ecotonal with few strongly affiliated species.  We use indicator species analysis to assess strength of this species-habitat affiliation.

Results/Conclusions

Among taxa (plants, orders of animals) there were significant differences in overall rates of affiliation with habitats along the grassland-forest continuum.  Some taxa exhibited low rates of affiliation between constituent species and any habitats along the continuum while other taxa displayed strong affiliation between constituent species and at least some habitats along the continuum.  However, the strongest affiliations tended to occur at continuum extremes –grasslands and forests – rather than between species and savannas.  This suggests that savannas are used by species more often as an ecotonal habitat rather than as a habitat whose characteristics strongly differentiate it from other habitats along the grassland-forest continuum.