Calculating the impact of plant diversity on ground-dwelling invertebrates in restored prairie of central Nebraska

The destruction of tallgrass prairie has been well-documented.  Recent restoration efforts seek to enhance recovery by re-establishing plant communities in hopes that consumers such as invertebrates will respond positively.  Practical management decisions include choosing the number of plant species that will maximize ecosystem function while minimizing costs.  The Nature Conservancy in south-central Nebraska has established plots with differing plant species richness.  Replicated plots included monoculture plots planted with big bluestem (Andropogon gerardii), low diversity plots (~9 species) and high diversity plots (~108 species).  We collected ground-dwelling invertebrates using 18-mm pitfall traps to assess whether high diversity of producers results in high richness and diversity of consumers.  Univariate analyses showed that plant richness  (P=0.002) and diversity (P<0.001) differed by treatment.  Multivariate (non-metric multi dimensional scaling ordinations and ANOSIM) analyses showed that plant communities were unique between plots as well (P<0.001).  However, invertebrates showed no significant differences in univariate (richness: P=0.72, diversity: P=0.64) or multivariate results (P=0.71).  Results suggest that although some insect groups are likely to respond positively to increased plant richness, ground-dwelling invertebrates did not differ by treatment.  Invertebrate assemblages may be influenced by factors we did not measure, indicating a need for future research.