After walking through the lush forest along the Saco River, it would be easy to overlook two tiny shrubs bursting from the gravel on the river’s bank.
The silverling and the hudsonia, already rare plant species, meet there to form an even rarer plant community. Like any other natural community, those plants help support the biodiversity along the river, creating specific relationships between animals, fungi and other organisms.
Up until last year, New Hampshire state botanists doubted the hudsonia-silverling riverwash barren plant community even existed anymore. So Bill Nichols and Amy Lamb decided to visit the Dahl Wildlife Sanctuary in North Conway to confirm their hunch.
They were wrong.
“And there it was about the same size as it was historically and so we were saying, well, I guess the community may be doing okay,” Nichols recounted.
He points to a clump of grayish-green flowers, the silverling, and small green needles shooting off from the ground, the hudsonia, growing next to each other.
That was the sight that led the two scientists to a weeks-long expedition along the Saco River, looking for known and unknown sites of the plant community.
“On some of the smaller areas we could just stay in the kayak and look out and say ‘Yeah, I don't really see anything,’ but most of the time we'd get out and look,” Lamb said.
Many of the most recent records they had, which were dated 30 to 40 years back, showed 11 known sites, most of them in New Hampshire, with only four in Maine.
Now, only four sites exist, including one in New Hampshire, Nichols and Lamb say.
According to Nichols, climate change is likely behind the community’s disappearance. In only a few decades, flood and precipitation events have become more frequent and more extreme. Studies also point that rivers are now seeing more flood events during their dry seasons, when species are not prepared for so much water.
Those trends can also be observed on the Saco River, Nichols said.
While the plant community requires a certain level of flooding and precipitation “to push back the woody vegetation, to move the sediment and also to discourage competition,” Nichols explained, “the level of disturbance associated with those high precipitation events was too much, it was untenable for this community.”
Moving farther north, Nichols and Lamb stop by what used to be the largest site of the hudsonia-silverling plant community in New Hampshire just a few decades ago. In a more remote spot of the river, the community used to cut through the floodplain forest and flower on both banks.
Now, all they find is a few clumps of hudsonia in a small patch which didn’t even meet the minimum standards to be classified as that community type.
“That increased flood intensity just completely, direct on nailed it and washed away both the sediments it relies on and the species,” Nichols said. “All gone.”
But their research has just begun. Lamb and Nichols hope to collaborate with other experts to better quantify their observations and look into other possible factors impacting the community’s health, such as recreation and development.
For the two scientists who originally thought the community had already been lost forever, the fact that it still exists, as precarious as it may be, comes with the hope of preserving what’s left.
“Things have intrinsic value and it’s our obligation to protect things just because they are what they are,” Nichols said. “And once it’s gone, it’s gone.”
Get more New Hampshire news in your inbox: Sign up for the free Rundown newsletter.
