1. Early-flowering forbs
The impact of functional group on aboveground biomass production and plant community composition
Acknowledgements
Mark Dixon, The University of South Dakota
Jeff Wesner, The University of South Dakota
Clarence and Sandy Pederson
Eva Soluk and Meghann Jarchow
Objective
Introduction
The tallgrass prairies of the Great Plains have suffered a loss of 88-99% due to agricultural conversion (4). As prairie ecosystems throughout North America decline, native prairie vegetation is lost. Within prairie ecosystems there are many species of plants and these plants can be categorized into plant functional groups or guilds (3). Tallgrass prairie plant functional groups consist of species that share similar ecological and morphological traits and that could viably functionally replace one another in the system (3). By observing and analyzing the changes in aboveground biomass and species composition that occur when different functional groups are grown independently, we can develop a better understanding of how plant functional groups affect early prairie establishment.
How does the seeding of different functional groups affect the aboveground biomass production and plant community composition in tallgrass prairies during the first two years after seeding?
Methods
Results
We measured aboveground biomass and plant community composition in July 2014 and 2015 in a field experiment with four treatments: C3 grasses, C4 grasses, forbs flowering early in the growing season, and forbs flowering late in the growing season (Table 1). Each functional group is represented by six species that are native to Clay County, SD. (Table 1). To determine plant community composition and aboveground biomass for comparison between years, randomly located 0.25 m2 quadrat samples were harvested within each plot via clipping by hand to ground level (1 quadrat/plot in 2014 and 2 quadrats/plot in 2015). Samples were then sorted by species and weighed. Aboveground biomass was compared between years, among treatments, and among the different functional groups of plants harvested using a repeated measures ANOVA. Plant community composition was compared using non-metric multidimensional scaling (NMDS) ordination.
We found no difference among functional group treatments between years (Figure 1). Except for a difference between C3 grass aboveground biomass between years (p<0.01), and late flowering forb aboveground biomass between years (p<0.01).
There were more seeded species present in 2015, but Canada wildrye was present in all functional group treatments in 2015 (Figure 1).
Between study years the plant community composition was distinct (Figure 2).
In 2015, Canada wildrye and catnip described at least 25% of the variation; whereas in 2014 Pennsylvania smartweed and lambsquarter described at least 25% of the variation.
Table 1) A list of all species that were seeded for each treatment in the experiment.
C3 grasses
C4 grasses
Early-flowering forbs
Late-flowering forbs
Canada wildrye
Elymus canadensis
big bluestem
Andropogon gerardii
narrow-leaved coneflower
Echinacea angustifolia
stiff goldenrod
Solidago rigida
Virginia wildrye
Elymus virginicus
side-oats grama
Bouteloua curtipendula
large-flowered beardtongue
Penstemon grandiflorus
Maximilian's sunflower
Helianthis maxamiliani
green needle grass
Nassella viridula
little bluestem
Schizachyrium scoparium
golden alexanders
Zizia aurea
rough blazing star
Liatris aspera
junegrass
Koeleria macrantha
Indiangrass
Sorghastrum nutrans
prairie larkspur
Delphinium virescens
heath aster
Symphyotrichum ericoides
blue joint grass
Calamagrostis canadensis
rough dropseed
Sporobolus asper
white prairie clover
Dalea candida
round-headed bush clover
Lespedeza capitata
western wheat grass
Pascopyrum smithii
upland wild timothy
Muhlenbergia racemosa
wild licorice
Glycyrrhiza lepidota
Illinois bundleflower
Desmanthus illinoensis
An example of the quadrat and clippers used to cut each sample by hand. Here the sample has already been collected.
2015
2014
Figure 1) A comparison of aboveground biomass (g/m2) for all four treatments in 2014 and Plants present in the plots are separated into functional groups: seeded C3 grasses (C3), seeded C4 grasses (C4), seeded early forbs (EF), seeded late forbs (LF), and unseeded species (unseeded)
Figure 2) An NMDS ordination showing a comparison of the treatments in 2014 and The biplot indicates with species that account for at least 25% of the variation. Polygons are drawn around treatments for each year separately.
Discussion
Works Cited:
Blumenthal, D. M., Jordan, N. R., & Svenson, E. L. (2005). Effects of prairie restoration on weed invasions. Agriculture, ecosystems & environment,107(2),
Fynn, R.W.S., Morris, C.D., and Edwards, T.J. (2004). Effect of burning and mowing on grass and forb diversity in a long-term grassland experiment. Applied Vegetation Science, 7, 1-10.
Kindscher, K., and Wells, P.V. (1995) Prairie plant guilds: a multivariate analysis of prairie species based on ecological and morphological traits. Vegetatio. 117:29-50
Reinking, D.L. (2005). Fire regimes and avian responses in the central tallgrass prairie. Studies in Avian Biology, 30,
Robocker, W., & Bonita J. Miller. (1955). Effects of Clipping, Burning and Competition on Establishment and Survival of Some Native Grasses in Wisconsin. Journal of Range Management, 8(3),  
There were fewer unseeded species and more seeded species in 2015 than in Prairie species began to establish in 2015 as is commonly found in tallgrass prairie restorations (1,2). The species composition began to switch from annual species common in agricultural fields, which was the former land-use at the site, to perennial plants.
C3 grasses were present in all treatments, with Canada wildrye being the most prominent. We have no evidence to suggest experimental error, but Canada wildrye is present in all of the plots. We believe that this is due to animal dispersal of the seeds after seeding in Canada wildrye is a strong early establishing species (5) that is expected to diminish as prairie restoration advances and slower establishing C4 grasses and forbs become more prominent (1).
Functional group did not have an effect on plant community composition in 2014 and There was no difference in the plant community composition as visualized with NMDS ordination among the treatments. However, we anticipate that over time the treatments will become distinct.