Cristol Fleming has gone out hunting for the first wildflower blooms of spring for close to four decades. She knows where every tiny bluish clump of rarephacelia can be found, where every fragile yellow trout lily grows.
And in the guide she co-authored on finding Washington, D.C.-area wildflowers, she writes that mid- to late April is the best time to see the forests and riverbanks carpeted with a riot of these delicate blooms.
So, it was with some consternation that the field botanist found two of her favorite early flowers — sprigs of white and purple “Harbinger of Spring” and graceful white twinleaf — in full bloom in late March.
“I was surprised to see that,” she said. “That’s something I would have expected two weeks later.”
Bloom hunters like Fleming, who for 40 years have been tramping through the woods, roaming along riverbanks and scrambling over rocky outcrops to document the first blooms of spring, worry that what they have been seeing is nothing less than the slow, inexorable shift of global warming.
They even have a name for it: season creep. And it’s happening all over the world.
For 1,000 years, the Koreans have recorded the first cherry blossoms of spring, so central is that flower to their cultural identity. For 300 years, the Europeans have meticulously tracked when grapevines bloom to time planting and harvest. On both continents, botanists are finding earlier and earlier blooming.
“When you gather together all the scientific studies that have documented this, we can see that about 80 percent of the species are changing earlier in the spring,” said Jake Weltzin, an ecologist with the U.S. Geological Survey.
Weltzin was in town last week trying to drum up support for the new National Phenology Network that he runs. Its aim is to do for the entire United States what bloom hunters like Fleming have done for the Washington area: track the patterns of season creep and explain why that matters to humans.
It has already begun to matter for the plant and animal world. In Europe, the leaves of the English oak are coming out earlier, Weltzin explained, which means the winter moth caterpillars that feed on them are also coming out earlier.
But the pied flycatcher birds that eat those caterpillars are still migrating north at that time, so when they do arrive, the caterpillars have turned into moths and are gone. That has decimated the bird population in recent years.
And these failures to adapt, or adapt in time, are what worry Fleming.
“Unlike animals, plants can’t just get up and move,” she said. “If they end up in a climate that’s too warm, well, they’ll just die.”
