Guest blogger: Suzanne Yorke, CREW Research Lab Assistant
Plant conservation work at the Cincinnati Zoo & Botanical Garden’s Center for Conservation and Research of Endangered Wildlife (CREW) was featured in The Public Garden, the journal of the American Public Gardens Association, earlier this year in an article entitled “The Race for Plant Survival” written by Janet Marinelli. The article discussed the important role that public gardens like the Cincinnati Zoo & Botanical Garden (CZBG) play in plant conservation, the technological advancements that are being made in this challenging work, and the goals for plant conservation in the future.
The article begins with the story of the 24-year (and counting!) conservation quest to bring the autumn buttercup, Ranunculus aestivalis, back from the brink of extinction, and how such large-scale conservation efforts have become increasingly collaborative.
Shortly after The Nature Conservancy purchased land in 1991 to protect the habitat of the autumn buttercup along Utah’s Sevier River, they realized that just setting aside protected land wouldn’t be enough. The population was dwindling too fast, and additional partners would be needed to save this federally listed species. Seeds were collected from the mere 20 remaining plants at the preserve and sent to CREW. Valerie Pence, CREW’s Director of Plant Research, germinated the seeds to grow a handful of genetically unique individuals. She then used her expertise in micro-propagation to develop tissue culture protocols for the autumn buttercup and the power of tissue culture to make hundreds of “copies” of these plants in vitro in test tubes.
The tiny plants were sent to Arizona to enter the care of the next partner in the process, the Arboretum at Flagstaff, which potted the plants in soil and prepared them for out-planting in their native habitat. The out-plantings and subsequent monitoring of the plants was achieved through additional partnerships with the U.S. Fish & Wildlife Service and Weber State University.
Three out-plantings since 2007 demonstrate how this reintroduction effort has required the long-term commitment and collaboration of several stakeholders to continue to boost the autumn buttercup population until it is self-sustaining. The autumn buttercup story is a great example of “integrated conservation”, whereby public gardens partner with government agencies, non-profit organizations, and universities to preserve endangered plant species. Learn more here.
Multifaceted conservation strategies are increasingly incorporating technology into species survival plans, which often combines reintroduction of plants into their native habitat, banking seeds and tissues in long-term storage, and maintaining living collections in gardens and arboreta. For example, the Frozen Garden in CREW’s CryoBioBank uses liquid nitrogen and cryogenic technology to store seeds and shoot tips of some of the most threatened plant species, like the autumn buttercup, at very cold temperatures.
However, even if species are banked, their native habitat may be changing faster than the plants can adapt to the changes. Advancements in molecular genetics ensure that public gardens are also preserving the genetic diversity of the species that are banked and in living collections. Therefore, when plants are ready for reintroduction, higher genetic diversity should increase their chances of survival in the wild and ability to adapt to changing conditions. Plants that are especially vulnerable to changes in climate include certain long-lived, slow growing tree species.
Globally, more than a thousand tree species are considered critically endangered. One aspect of their biology that makes them a conservation challenge is that many species of trees produce seeds that are not easily frozen in seed banks. Oaks, for example, produce large acorns that don’t survive freezing. CREW scientists helped develop techniques to dissect the tiny oak embryos out of the acorns, which they were then able to cryopreserve.
CREW scientists tested the technique using four endangered oaks and three were successful! More research is needed, but these advancements at CREW will improve conservation strategies for endangered oaks and other large-seeded tree species.
Unifying the plant conservation effort is the Center for Plant Conservation, which is made up of 39 gardens, including CZBG. This network of gardens safeguards seeds, tissues, and specimens of 788 of the rarest native plant species in the United States. With nearly 5,000 species considered at risk, there is much work ahead to achieve the goals of the Global Strategy for Plant Conservation, which includes preserving 75% of plant species in living collections and seed banks by 2020.
While achieving these goals may seem daunting, what is known is that the future of plant conservation will continue to be collaborative, it will rely on technological advancements like those developed at CREW, and public gardens like CZBG will continue to be at the forefront of this critical conservation effort.