By KEVIN DUFFY
Capital News Service
LANSING — As climate change threatens wet landscapes with persistent and intense droughts, natural resource managers are looking for ways to preserve the remaining habitats of the rare species such as the orchid known as white lady’s slipper.
It’s not easy.
“There’s a big problem with managing climate sensitive species,” said Sue Galatowitsch, a professor of fisheries, wildlife and conservation biology at the University of Minnesota.
That problem – the uncertainty of the future climate – was the focus of a recent study of how best to protect the small white lady’s slipper.
In the Great Lakes region, the lady’s slipper is rare, threatened or endangered in Michigan, Minnesota, Wisconsin, Illinois, Indiana, Ohio and New York. It’s no longer found in Pennsylvania.
According to the Michigan Natural Features Inventory, its territory is limited to southern Michigan, mainly “within a narrow band from Berrien and Kalamazoo counties in the southwest to southeastern Michigan, where it is concentrated in Livingston, Oakland, Washtenaw and Jackson counties.”
The inventory, a project of the Department of Natural Resources (DNR), said the orchid has also been found in two locations in the Thumb.
However, DNR said, “About one-third of approximately 81 recorded occurrences have succumbed to ecological succession or loss of habitat due to development.”
Galatowitsch said, “Management of very specific, local sites is important because conservation is really a boots on the ground effort.”
State plans guide policy, but day-to-day decision-making usually happens one place or person at a time, she said.
Managers need to know what climate impacts they can expect, how likely they are and what local strategies best promote native plant growth, Galatowitsch said.
“Both the orchid and its wet prairie or meadow habitat are increasingly vulnerable to climate change,” said Laura Phillips-Mao, the study’s lead author and adjunct professor at the University of Minnesota.
Lady’s slipper flowers from late May to early June. It is named for the shape of its inflated lower petal.
The plant’s habitat is managed using controlled burns – necessary for a healthy and diverse prairie – and targeted invasive species removal.
DNR points to the need for more research.
“Due to the significant development pressure in southern Michigan where this species is most common, research regarding compatible development activities is of highest priority.
“Specific precautions that must be taken in order to maintain fen hydrology should be determined and proposed as policy,” it said.
“The role of fire as a management tool to minimize succession or the invasion of exotic species should also be investigated,” it said.
It also advocated more studies about the white lady’s slipper’s breeding biology and genetic diversity to “provide a sounder basis for making management decisions.”
The new study used 54 climate scenarios to predict how populations of lady’s slipper could change over 100 years within the Expandere Wildlife Management Area in southwest Minnesota.
“We considered multiple scenarios and stressors,” Phillips-Mao said. “We asked what happens if the water table drops 6 inches. We asked what if drought becomes twice as frequent. What if, on top of those hydrologic factors, invasive species are introduced?”
Drought frequency and the depth of the water table are climate variables that were adjusted in the computer model. The impact of invasive species, especially by the non-native reed canary grass, was also considered.
“Minimizing the impact of invasive species matters a lot to sustain populations through these big climate events that we will probably not be able to control,” Galatowitsch said.
Not all the impact is negative.
“If you change the environment, some sites will become less suitable and some may become more suitable, and with some lag time, the plants will respond to that,” she said.
The effects of drought and changes in the water table are similar for the water-sensitive lady’s slipper, according to the study.
“But when you start combining impacts, there’s a bigger decrease in the population,” Phillips-Mao said.
For example, when a water table is lowered and invasive species are introduced, the damage is worse than when drought is combined with an invasion. And the first combination could prove fatal to remaining lady’s slippers.
“While we were not able to identify a single factor that had the greatest impact on lady’s slipper, we found useful information for management,” Phillips-Mao said.
The white lady’s slipper is extremely sensitive to invasion by reed canary grass, cattails and woody non-natives. And the orchid continues to suffer even after invasive plants are removed.
Reducing environmental stressors by removing invasive species is easy to do and it helps.
“But if it’s assumed that controlling invasive species is sufficient to save the plant, it probably isn’t,” Phillips-Mao said.
“We need to start thinking about additional strategies that may seem riskier,” she said. Such strategies could include transplanting species into future suitable habitat.
What actually plays out depends on the model’s accuracy. Researchers will be watching.
Galatowitsch said, “There will be an uptick in the monitoring of the plant in the future.”
Researchers recommend that land managers monitor the water table to get a sense of which of the 54 scenarios is closest to what’s happening.
“We want to know what we’re heading toward and how to lessen the impact to rare species,” Galatowitsch said.
Kevin Duffy writes for Great Lakes Echo.
ADDITIONAL RESOURCES FOR CNS EDITORS
“Model-based scenario planning to develop climate change adaptation strategies for rare plant populations in grassland reserves”: http://www.sciencedirect.com/science/article/pii/S000632071530135X