Question: Does increasing Festuca 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 × 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, Festuca increased most on species-poor plots, and Festuca abundance remained low on species-rich plots.

Conclusions: Festuca 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.

Nomenclature: Anon. (1986).