Leaf litter depth has only a small influence on Ranunculus ficaria (Ranunculaceae) biomass and reproduction

Ranunculus ficaria is an invasive plant species in the northeastern United States, especially in urban riparian habitats. Changes in the frequency and intensity of flooding events in these urban riparian corridors create patches of heavy litter and patches of bare ground. Many plant species either cannot penetrate deep litter, or they are susceptible to freezing temperatures and drying conditions on bare ground. This can result in competitive advantages for invasive species that are adapted to these varying conditions. We conducted a field experiment to test the effects of leaf litter depth on R. ficaria biomass, bulbil production, flower production, and seed production under deep (20 cm) litter, intermediate (10 cm) litter, shallow (5 cm) litter, and bare ground along an urban stream in Louisville, Kentucky. Deep litter and lack of litter decreased plant biomass compared with shallow litter. Bulbil production was not significantly different across treatments. Flower and seed production were only reduced in deep litter. Ranunculus jicaria's ability to maintain production across a large range of litter depths may provide a competitive advantage over plant species not adapted to varying litter depths.
INTRODUCTION Invasive plant species are important economic and environmental pests, posing threats to endangered species, altering native habitats, decreasing biodiversity, and facilitating the establishment of other invasive species (Pimentel et [...]