Todd Bittner, Cornell Botanic Gardens
Cornell Botanic Gardens has been working to conserve American Globeflower (Trollius laxus ssp. laxus) ex situ through seed banking efforts across multiple populations and in situ within two Garden-owned natural areas. The in situ conservation work has primarily focused on habitat protection and invasive species, deer, and nuisance beaver control. A population viability analysis (PVA) conducted for Eames Fen indicated a high likelihood of local extirpation, prompting a population augmentation effort. The seven- year augmentation, with a donor site 200-250 meters from the original population, has been successful with over 340 plants successfully outplanted and a 95% or higher survival rate.
Despite active management in the original Eames population, the globeflower numbers declined 62% (down to 63 plants) by 2018. Recent research has identified partial shade between 20 – 40% available light to be preferred habitat conditions for plants. To quantify the existing light conditions and inform potential canopy cover manipulation at Eames, we deployed an array of HOBO light sensors during the peak of the growing season in the fen and a nearby control full sun site. The average available light was 12.56% (SE +/- 1.4; range 6.8 to 39.5%), placing it well below the favored light range. Given the strong correlation, we embarked on a canopy thinning study with the goal of increasing available light to 30-40%. In the winter of 2018-2019, we removed 45 northern hemlock trees (Tsuga canadensis) from the eastern, southern, and western perimeter of the fen, with a basal area totaling 14.1 ft2. In 2019, we intend to replicate the environmental monitoring and corresponding response of the individual globeflower plants and population to inform future management actions.