Forest Focus: Ex Situ Conservation of Two Globally Rare Dwarf Evergreen Shrubs – Technologist

Article content contributed by Cheyenne Moore, Ecological Program Specialist, Pennsylvania  DCNR Bureau of Forestry. Read Original. 

The Pennsylvania Plant Conservation Alliance (PPCA) is a DCNR program housed in the Bureau of Forestry, charged with conserving and stewarding Pennsylvania’s dozen or so globally rare plants. When tackling rare plant conservation, one of the first steps is “ex situ” conservation, or “off-site” conservation. This is establishing a collection of the population or species outside of the wild. This can be done through seed banking or with living collections. This helps guard against an event that could result in significant or total loss of a population (e.g., wildfire, landslide, human disturbance). Ex situ collections are an insurance policy that if something happens, the unique adaptions and genetics found in that population will not be lost.

While the Bureau of Forestry does not have the capacity to seed bank or keep plants in-house, the
PPCA has identified some key partners to help with this. Both Longwood Gardens and Mt. Cuba
Center have been working with the PPCA to get various species into ex situ collections. They have
been working with PPCA on a suite of species prioritized for ex situ conservation in PA. This
includes species with three or fewer populations left in the wild in the state and includes box
huckleberry (Gaylussacia brachycera) and Canby’s mountain-lover (Paxistima canbyi). Both globally rare plants are Appalachian endemic species that reach the northern end of their range in
Pennsylvania. There are three populations of each in Pennsylvania. One population of
box huckleberry occurs on Bureau of Forestry land at the Box Huckleberry Natural Area in Tuscarora State Forest. One population of Canby’s mountain-lover also occurs on DCNR land at a state park.

Getting plants into ex situ collections is not always as straight forward as collecting seed for seed
banking or propagation. Both box huckleberry and Canby’s mountain-lover are not known to set viable seed in Pennsylvania. Research into box huckleberry seeds has shown they fail to germinate, and only one seed has ever been found on Pennsylvania Canby’s mountain-lover. The alternative in both cases is taking spring cuttings of the plants and rooting those cuttings in a mist chamber or moist soil. Once plants are rooted, trained horticulturists can divide the cuttings and multiply the number of plants.

Dr. Peter Zale at Longwood Gardens has been instrumental in getting these protocols established. One of three populations of box huckleberry is in collection, with plans to get cuttings from the other two populations this spring. Two of the three populations of Pennsylvania Canby’s mountain-lover are in collection, and efforts are underway to sample the third (of three) in the coming year. PPCA is also now helping to connect Longwood to other states with struggling populations of these species. For example, cuttings will be collected and sent from Ohio’s one of two rapidly declining populations of Canby’s Mountain lover and sent to Longwood in the
next couple of months. Chris Bedel, steward at the Ohio population, said it best, “These collaborations are exciting because conservation of plant species works best at the range wide scale not just the state scale.”

In addition to serving as an insurance policy, these ex-situ collections can also potentially help
Pennsylvania increases genetic diversity. Both Canby’s mountain-lover and box huckleberry are long-lived, clonal shrubs, so botanists suspect that there is not enough genetic diversity within the populations to allow for sexual reproduction, and the remaining populations are too far apart for natural gene flow. However, once they’re doing well in a greenhouse, Dr. Zale can cross-fertilize individuals from different populations and see if that results in viable seed. Stay tuned!

Something else to be on the lookout for is the results of the populations genetics research that Bucknell University is doing on both species. The work is funded by a Wild Resources Conservation Program grant and will help us better understand the genetic diversity, rates of inbreeding, and gene flow of the plants both at the Pennsylvania scale as well as range wide. PPCA and the PA Natural Heritage Program have been facilitating the sampling outside of PA through various Natural Heritage and Plant Conservation Alliance contacts in the U.S. Not only has this served to help the researchers, but it also gets conservations going about how the species are doing range wide, what management has been helpful, and more.

The Pennsylvania Plant Conservation Alliance looks forward to sharing results from ongoing work with these species as well as others! The PPCA is a part of the Bureau of Forestry’s Natural Heritage Section in the Conservation Science Ecological Resources Division.

Forest Focus is a project of the Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry. This article shared courtesy of DCNR, Bureau of Forestry.