Pondberry needs light to thrive

by Virginia McDaniel, Science Writer • June 2, 2022

pondberry shrub with red berries — Pondberry is an endangered, aromatic shrub that grows on the edges of wetlands and in seasonally flooded hardwood forests in the Coastal Plain. Photo by Hugh and Carol Nourse.

Pondberry (Lindera melissifolia) can tolerate deep shade and flooded soil – conditions that would kill many plants. However, the endangered shrub prefers more light and less flooding, as a team of USDA Forest Service researchers led by Ted Leininger shows.

Leininger and colleagues have conducted several pondberry studies at the Flooding Research Facility on the Theodore Roosevelt National Wildlife Refuge Complex in Mississippi. The facility has 12 impoundments that can be flooded and drained to mimic natural flooding regimes — like the seasonally flooded hardwood forests where pondberry is found. The researchers used shade cloth to mimic different light levels.

Pondberry growing in high light conditions (70% sunlight) produced more flowers and more fruits than pondberry in shadier conditions (33% sunlight), as the study shows. Pondberry growing in deep shade (2% sunlight) did not flower or fruit and grew very slowly.

Although pondberry can survive in deep shade, it produces more fruit and more vegetative growth when in the sun. This study, along with previous research, suggest that pondberry would benefit from active management. Knowledge gained from these studies could be used to develop thinning guidelines for bottomland hardwood forests that would provide optimal light environments in which pondberry could thrive.

Pondberry grows in wetlands, so it has adaptations to survive. None-the-less, flooding is a real stressor for pondberry. Plants that were flooded for 45 or 90 days produced 85% fewer fruits and less vegetative growth than plants that weren’t flood.

Understanding how management actions affect an endangered species, especially those that make it more viable, will help lessen the risk of extinction. Given pondberry’s specialized habitat, ensuring successful reproduction is critical to its survival.

The Army Corps of Engineers provided funding for the project.

Read the article in Ecology and Evolution. For more information, email Ted Leininger at theodor.leininger@usda.gov.