The effect of site characteristics on the reproductive output of lesser celandine (Ranunculus ficaria)

Background/Question/Methods

Lesser celandine (Ranunculus ficaria), an invasive plant brought over from Europe, is becoming widespread throughout the north eastern and north western United States. Despite being aesthetically pleasing, lesser celandine can cause extensive damage to communities and ecosystems. Its rapid reproductive rates and spring ephemeral growth pattern, linked with its high production of bulbils and tubers, allow lesser celandine to disperse and establish more rapidly than its local competitors. This invasive species is able to outcompete many native plant species due to its earlier growing season and its ability to create extensive dense mats that limit the resources available during a short spring window critical for native species.

This study aims to explore the effects that site characteristics have on the reproductive output of this herbaceous invasive. We examined the reproductive output (seed, bulbil and tuber production rates) in lesser celandine plants collected from plots spanning a disturbance gradient away from a river. We hypothesize that seed production will be highest in moist floodplain at intermediate distances from rivers.

Results/Conclusions

Some sites reflected our expected hypothesis, where the abundance of lesser celandine abundance was greatest at intermediate distances from the river, which receive intermediate disturbances. The lesser celandine distribution was generally sparse near the river (0 m transects) and then a dense monoculture was observed to the 20 m transect, after which we started to observe a greater abundance of other species. Some plots displayed a consistent vegetative mat of lesser celandine that extended beyond my last transects (25 m), and this was primarily observed in locations consisting of a well-established, successful population of lesser celandine. 

Bulbil production was as high as 5.8 per plant and this figure did not vary a great deal between intermediate quadrats in areas of high infestation. Densities of lesser celandine were found to be as high as 2375 plants/m² in some areas. It appears that bulbil germination rates by the end of the year are extremely high, reflecting little evidence of any dormancy mechanisms. Bulbil production and lesser celandine abundance is highest in moist floodplain at intermediate distances from rivers, where plants will experience moderate levels of disturbances along with moist yet not fully saturated soils. This study was able to expand on the current limited understanding of lesser celandine, which can prove helpful in the aiding of more efficient management and control of its spread.