Get reliable science

Wildlife and livestock herbivory as well as ecological site can influence plant community composition. Population ecology can provide insight into how these dynamics influence plant communities. We selected two different ecological sites, thin claypan and loamy, at a research site near Mahto, South Dakota, that had areas with and without prairie dogs. Within each main plot (30x30m), four subplots (15 x 15cm) were randomly located. All tillers of western wheatgrass [Pascopyrum smithii (Rydb.) ?. L�ve] within subplots in each main plot was marked with a colored wire in June 2014. We focused on western wheatgrass because it occurred in all sites. Non-livestock grazed treatments were fenced two years prior to starting the study. Treatments without prairie dog herbivory were located off of prairie dog colonies. Following initial marking in June 2014, plots were visited in September 2014 and June 2015. At each visit, live, dead and new tillers were recorded and new tillers were marked with a different colored wire. Tiller per tiller recruitment was determined by counting the number of new tillers and dividing by number of live tillers present at the previous sampling. In September 2014, thin claypan sites produced 1.16 new tillers per live tiller but on loamy sites it was only 0.88 (P=0.0020). In June 2015, tiller per tiller production on loamy sites was higher than thin claypan but the ratio at both sites was less than 1. In September 2014, treatments without prairie dogs averaged 1.26 tillers per tiller compared to 0.79 for treatments with prairie dogs (P<0.0001); however, in 2015 treatments without prairie dog only produced 0.31 tillers per tiller compared to 0.51 for treatments with prairie dogs (P=0.0281). These preliminary findings suggest both ecological site and type of herbivory influence population dynamics but more data is needed to fully evaluate these influences.