Old-Field Grassland Successional Dynamics Following Cessation of Chronic Disturbance

Question: Does increasing i\u3eFestuca canopy cover reduce plant species richness and, therefore, alter plant community composition and the relationship of litter to species richness in old-field grassland? Location: Southeastern Oklahoma, USA. Methods: Canopy cover by species, species richness, and litter mass were collected within an old-field grassland site on 16, 40 m x &#;40 m plots. Our study was conducted during the first three years of a long-term study that investigated the effects of low-level nitrogen enrichment and small mammal herbivory manipulations. Results: Succession was altered by an increase in abundance of Festuca over the 3-yr study period. Species richness did not decline with litter accumulation. Instead, i\u3eFestuca increased most on species-poor plots, and i\u3eFestuca abundance remained low on species-rich plots. Conclusions: i\u3eFestuca may act as an invasive transformer species in warm-season dominated old-field grasslands, a phenomenon associated more with invasions of cool-season grasses at higher latitudes in North America