A regenerated forest can appear tall, dense, and verdant. Revived wetlands can hum with insects and flutter with birds. However, upon closer inspection, scientists have discovered that some of the tiniest inhabitants, such as specific mosses, lichens, algae, and fungi, are often still absent.
Restoring ecosystems like forests and wetlands can aid in protecting declining species of animals and plants and support their recovery. Nevertheless, recent studies indicate that not all species return at the same pace. Some of the smallest, least conspicuous residents may remain scarce or missing for extended periods, potentially impacting other species.
Ellen Macdonald, a botanist at the University of Alberta, has devoted her career to examining forests, with a focus not on the trees but on the minute flowers, mosses, liverworts, and lichens that thrive in their shadow, among their roots, or on their bark surfaces.
According to Macdonald, the number of species in a forest understory far surpasses that of tree species. To the average observer, a regenerated forest decades after logging may closely resemble an untouched one, brimming with towering trees, birds, and insects. However, Macdonald has noted a sense of something amiss while walking through regrown coniferous boreal forests, even though pinpointing the exact issue may require data collection.
Macdonald conducted a study by combining her own research with global data to assess the timeline for plants and animals to reappear as boreal forests regenerate post-clearcutting. The research, recently published in the journal Nature Sustainability, revealed that birch and aspen forests and their inhabitants typically recover within 25 years, whereas conifer forests take significantly longer. In conifer forests, understory plants, particularly lichens, mosses, and liverworts, can take 85 years or more to reestablish, with some species failing to recover even after a century of available data.
The phenomenon is not exclusive to boreal forests. Researchers studying restored habitats like wetlands have also observed that although these areas may appear healthy, some less visible species remain absent. This decline, described as “dark diversity” by biologist Viktoria Wagner, signifies a silent form of species loss, where species vanish from locations they once inhabited, diminishing the overall species diversity within specific sites.
The absence of these species can impede recovery and have unseen repercussions. Algae, despite their small size, play a significant role in global oxygen availability and food production through photosynthesis. Therefore, declines in species diversity can adversely affect ecosystems and other species within them.
Understanding these patterns can guide landscape managers in preserving more species. Macdonald suggests that selective or partial harvesting of conifer forests might be more beneficial than clearcutting to aid in species recovery. Similarly, the preservation of algae habitats, as emphasized by researcher Michael Melkonian, is crucial to protecting the diverse species that inhabit them.
Preserving biodiversity necessitates more than safeguarding isolated habitats; it requires maintaining and restoring sufficient habitat for species to persist across landscapes. Active interventions are essential to counteract ongoing species loss and ensure the survival of diverse ecosystems.