Climate Change Is Resetting The Clock For Missouri Wildflowers. Will It Affect Their Survival?
To some, the bundle of yellowing pages might have looked like trash.
But Peter Hoch suspected the notes tucked away in the Missouri Botanical Garden archives could be something special.
“One of the archivists came in and said, ‘I found these weird notes that look like a list of plants from Shaw Nature Reserve,’” remembers Hoch, a curator at the garden. “I immediately thought, ‘Oh God, I have to see these.’”
The pages contained detailed data collected in the late 1930s and ‘40s by prominent botanist Edgar Anderson, documenting the bloom periods of native wildflowers at the nature reserve in Gray Summit, Missouri.
Though many of the same species can still be found peppering the reserve’s forested hillsides and shady glades, climate change is shifting when they bloom. Researchers in St. Louis are using the once-forgotten data as a springboard to explore how climate change has reshaped this ecosystem over the past 80 years — and how it could affect the survival of native plants in the future.
Plants and animals use temperature and other environmental cues like a calendar to decide when to migrate, breed or emerge from their winter dens.
But for many species, climate change is disrupting those natural rhythms. Historical datasets like Anderson’s are rare and extremely valuable to scientists, because they provide a snapshot of how things used to be.
Not long after the pages were unearthed in 2009, Hoch and Washington University graduate student Nicole Miller-Struttmann began pouring over them.
“It took some detective work,” said Miller-Struttmann, now an assistant professor of biology at Webster University. “Hours of going back and figuring out what species [Anderson] was talking about, because species’ names have changed, and what he meant in his notes.”
They decided to repeat the original study, hiking the same trails every week for four years and noting when different wildflowers were blooming to measure how much flowering times had changed since the 1930s.
Of the hundreds of species they documented, a pattern emerged: Summer wildflowers are now blooming longer than they used to — in some cases, by up to a week. “It’s significant, when you think that some of these species only bloom for a couple weeks,” Miller-Struttman said.
A pile up of wildflower species
Wildflowers that bloom for longer periods could lead to greater overlap with other species and competition for the same pollinators.
Still, it’s unclear what this seasonal pile up of species could mean for native wildflowers, said Matthew Austin, a postdoctoral researcher with the Living Earth Collaborative at Washington University.
“If there are more flowering species in the environment, there's a greater likelihood that a pollinator will visit multiple species while out foraging,” Austin said. “This is important, because in order for a flower to reproduce, it has to receive pollen from its own species.”
In other words, a bee presented with a smorgasbord of flowering plants might flit from species to species, dusting flowers with the wrong type of pollen. That could push more plants to self-pollinate — an “extreme form of inbreeding” that is slightly better than getting pollen from the wrong species, Austin said.
To understand how this could affect the reproduction and survival of Missouri wildflowers, Austin plans to pollinate hundreds of flowers by hand this year at Shaw Nature Reserve.
Kneeling on a forested hillside covered in clumps of blue phlox and Canadian wood betony, Austin collects pollen from individual flowers in a plastic tube, attracting curious looks from passersby.
To ensure no pollinators visit his flowers, he slips sheer white wedding favor bags over the buds before they open. But just as he removes one of the bags from a Jacob’s ladder flower to tap the pollen onto its sticky stigma, a tiny metallic green sweat bee lands on it.
“It just snuck right in there while I had it unbagged,” Austin said, striking that particular flower from the study. “You always want what you can’t have, right?”
He moves on to the next flower, a human meticulously doing the work of a bee.
It’s a slow, repetitive process, but Austin hopes the results will help us better understand this complicated ecosystem, even as climate change reshapes it.
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