Data from: Birds and butterflies respond to soil-induced habitat heterogeneity in experimental plantings of tallgrass prairie species managed as agroenergy crops in Iowa, USA

1. The maintenance of habitat heterogeneity in agricultural landscapes has
been promoted as a key strategy to conserve biodiversity. Animal response
to grassland heterogeneity resulting from spatiotemporal variation in
disturbance is well documented; however, the degree to which edaphic
variation generates heterogeneity detectable by grassland wildlife has
proven more difficult to study in natural settings. 2. We conducted a
field experiment to study how soils directly affect vegetation structure
and composition and indirectly affect bird and butterfly assemblages using
plantings of tallgrass prairie species managed as agroenergy crops in
Iowa, USA. The experimental design included four vegetation treatments of
varying species richness replicated on three soil types. 3. Habitat
characteristics varied widely among soils. Crops on sandy loam, the
driest, most acidic soil with the lowest nutrient content, developed
shorter, less dense vegetation with sparse litter accumulation and more
bare ground compared to crops on loam and clay loam. 4. Birds and
butterflies responded similarly to soil-induced variation in habitat
characteristics. Their abundance and species richness were similar on all
soils, but their assemblage compositions varied among soils in certain
vegetation treatments. 5. In low-diversity grass crops, bird assemblages
using sandy loam were dominated by species preferring open ground and
sparse vegetation for foraging and nesting, whereas assemblages using loam
and clay loam were dominated by birds preferring tall, dense vegetation
with abundant litter. In high-diversity prairie crops, the species
composition of forbs in bloom varied among soils and strongly influenced
butterfly assemblages. 6. Synthesis and applications. Prairie agroenergy
crops established with identical management practices developed variable
habitat characteristics due to natural edaphic variation, and this
heterogeneity influenced the spatial distribution of bird and butterfly
assemblages due to differential habitat use among species. This finding
suggests that if unfertilized prairie crops were grown for agroenergy by
land managers large-scale, soil-induced habitat heterogeneity would
promote wildlife diversity within and among fields, further increasing the
habitat value of these crops compared to the fertilized, annual
monocultures that currently dominate the agricultural landscape. Our study
also highlights the need for managers to consider soil properties when
selecting sites to restore grassland habitat for species of conservation
concern.