Experimental seed addition trials for the wood-poppy (Stylophorum diphyllum)

These data were collected as part of a PhD project to test the drivers of rarity of the wood-poppy (Stylophorum diphyllum). The wood-poppy is listed as endangered in Canada's Species at Risk Act (SARA). The study tests the efficacy of species distribution models (SDMs) to estimate suitable habitat for experimental seed addition trials within nine 1-hectare (100 m x 100 m) sites in southern Ontario. Within each site we selected nine plots stratified by observed soil moisture and canopy light levels. We caged half of the sub-plots to exclude seed predators (i.e., rodents). We planted 25 seeds into each sub-plot (4050 total seeds). We measured abiotic microsite characteristics in each plot including canopy light, soil moisture, and relative temperature differential. We planted the seeds in August 2021, recorded seedling emergence in spring 2022, and year one seedling survival in 2023. We removed cages with no germination and opened cage tops that were restricted plant growth throughout our censuses. We found the SDMs did not predict seedling emergence or short-term survival, suggesting there is not a lack of suitable habitat available. Instead, we found dispersal limitation coupled with seed predation drive rarity (at least for early life-stages). The files contain year one emergence (2022), year two survival (2023), and environmental plot (n=81) data. These files are associated with Emma R. Neigel’s PhD dissertation and the article, "Dispersal limitation and seed predation drive rarity of a plant species at its range edge. Neigel, Emma R., Timothy D. Schwinghammer, and J.L. McCune. Journal of Ecology. DOI: 10.1111/1365-2745.70083".