A seed sowing experiment was undertaken at the Nelson Environmental Studies Area, Kansas (USA; 39°03′N, 95°12′W) on an upland hayfield/pasture abandoned in the early 1980s (historically ploughed). Seed, with or without litter removal/clipping, was sown to assess if this assisted recovery of native prairie plant diversity.
The site was a 20 ha field dominated by four perennial grasses: non-native smooth brome Bromus inermis and tall fescue Festuca arundinacea; and native Kentucky bluegrass Poa pratensis and broomsedge Andropogon virginicus.
In autumn 1999, 40 (2.5 x 2.5 m) plots, subdivided in to four (1 x 1 m) quadrats, were established. To each plot, a factorial combination of treatments was assigned randomly to quadrats:
1) sowing: seeds of 32 grassland species; seeds not sown; 2) disturbance: 2000 and 2001, litter removed and soil raked in January and clipping to 15 cm in April and June; in 2002 and 2003, clipped in April (vs. no disturbance).
In 2005, above-ground plant biomass was harvested in quadrats mid-June and late September. Root samples were extracted to estimate root biomass. Light interception of the canopy was measured in June and September, prior to harvest. Soil samples were taken and analysed for percent soil organic matter, soil carbon and nitrogen.
In 2005, in non-sown plots sown species accounted for less than 2% of total biomass, on average; in sown plots, sown species accounted for over 87% of biomass. Annuals and short-lived perennials significantly decreased, and long-lived perennials significantly increased, in sown plots.
In unsown plots total species richness averaged 7.5/quadrat in unsown undisturbed, and 8.5 in unsown disturbed plots. Diversity in sown plots was higher and enhanced in disturbed plots (species richness: 12.6 in undisturbed; 15.1 in disturbed).
Overall, after six growing seasons, sown plots had increased native species and lower non-native species abundance, and increased diversity. Associated changes (increases in light capture, litter biomass, root biomass and root carbon storage) indicate ecosystem function more like native prairie.
If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://onlinelibrary.wiley.com/doi/10.1111/j.1526-100X.2007.00277.x/full