Effect-functional traits of nine bunchgrasses native to the blue ash-oak savanna of the Inner Bluegrass Region of Kentucky

Background/Question/Methods

As part of a restoration ecology study, a monoculture experiment was conducted from 2009 to 2011 to study the effect-functional traits of nine bunchgrasses native to the Blue Ash-Oak Savanna of the Inner Bluegrass Region of Kentucky.  Nine grasses, plus a species mixture treatment replicated 10 times created 100-2 m² plots in a completely randomized design.  Biomass production, life history traits, and nutrient cycling measurements were taken on the nine grasses which included six C₃ species and three C₄ species.  The C₃ species include four Elymus species that are well documented in historical records, Dicanthelium clandestinum, and Chasmanthium latifolium.  The C₄ species are Tridens flavus, Panicum anceps, and Andropogon virginicus.  A litter decomposition study, a nitrogen cycling study, soil parameters, a clipping experiment, and a seed germination study are included in this experiment but only biomass data and % Total Carbon and Nitrogen data are included in this presentation. 

Results/Conclusions

Biomass measurements were taken at peak biomass (or time of flowering) due to the significant seasonal and life history variation of the nine grass species.  The Elymus species flowered early spring/summer and was dormant during the heat of the summer.  The other species flowered later and did not have a dormant period during the growing season.  There was significant monthly average precipitation variation between the three years of this study.  2010 was a drought year (38.99 in/yr) with 65% of the precipitation of 2011 (60.02 in/yr) which was an unseasonably moist year.  In general, C₃ species showed more plasticity in aboveground biomass, plant height, and tiller number.  C₄ species had higher allocation/ tiller while the Elymus were the most prolific tillers.  As expected, C₃ species had higher C/N ratios than the C₄ species but interesting patterns are seen with % total nitrogen between the drought year and wet year.  In general, C₃ species had higher total %N in the drought year (2010) and C₄ species had higher total %N in the wet year (2011).