Plant Species Diversity and Dominant Plant Functional Types Control Productivity in a Reclaimed Mineland Prairie

Tallgrass prairie ecosystems in North America sustain globally important plant and animal biodiversity while providing ecosystem services, including biomass production, forage for livestock, and carbon sequestration. Land use change has left less than 1% of North American prairies intact, and opportunities are needed for their restoration. There has been increasing interest in the establishment of prairies on degraded former minelands, where significant challenges exist in reestablishing historic vegetation communities. We examined how the productivity and diversity of mineland prairies were influenced by varying restoration treatments that had been applied nearly a decade previously. We utilized an existing prairie research plot network established using seed mixes containing from one to seven different species and differing fertilization and tillage treatments. We calibrated a non-destructive method to assess prairie biomass and used it to assess the productivity and diversity across 312 research plots. The results showed that, with the exception of C4 grasses, few originally seeded species were present. Significant differences in species richness existed as a function of the interacting effects of seed mix type and fertilization treatment. Unfertilized plots generally had a higher species richness, particularly where larger numbers of species were included in the mixes. Prairie biomass was significantly greater in seed mixes containing big bluestem (Andropogon gerardii) and was also significantly related to Shannon diversity. Our results suggest that the establishment of (Andropogon gerardii) is fundamental to maximizing the diversity and productivity of mineland prairies, especially in the absence of follow-up management. The results also suggest that caution should be exercised when considering the use of fertilizer, as this may reduce the diversity of native species by favoring competitive non-native species such as some C3 grasses.