Tiny species vanishing from restored forests and wetlands, U of A researcher finds

Restored forests and wetlands can look lush and thriving with birds and insects returning—but a University of Alberta botanist's research reveals a hidden loss: the tiniest species are often still missing years or even decades later.

Ellen Macdonald, a U of A botanist, has spent her career studying the small inhabitants of forests—the flowers, mosses, liverworts, and lichens growing in shade, among roots, and on bark. "There's way, way, way, way, way more species there than there is a tree species," she said.

Macdonald combined her own research with global data to examine how long plants and animals take to return as boreal forests regrow after clearcutting. The study, published in the journal Nature Sustainability, found that birch and aspen forests and their inhabitants recovered within 25 years. But conifer forests told a different story: understory plants—especially lichens, mosses, and liverworts—took 85 years or more to return. In some cases, they had not recovered even after a century of available data.

The pattern extends beyond forests. German botanist Michael Melkonian studied restored wetlands near his home in southern Germany that had been drained for logging decades earlier. The bogs "superficially looked very nice" after restoration and replanting, with wildlife and carbon-storage benefits. But beneath the water, Melkonian found only a handful of desmid algae species where he expected hundreds. "The diversity of algae was not there," he said.

Viktoria Wagner, an associate professor in the Department of Biological Sciences at the U of A, describes this pattern as "a silent form of loss." Species don't necessarily vanish entirely, but disappear from places where they once lived, reducing the diversity at individual sites. The ecological consequences remain unclear but potentially significant: these tiny organisms often form the foundation of larger food webs and ecosystem function.

To an average person walking through a regrown forest a few decades after logging, the landscape appears much like one never cut—full of tall trees and wildlife. Noticing what's missing requires data collection and expertise. For many restored habitats, that documentation simply hasn't happened yet.