A regenerated forest can present as tall, lush, and verdant. Revived wetlands can be abuzz with insects and alive with birds. However, upon closer examination, scientists are discovering that some of the smallest inhabitants, such as specific mosses, lichens, algae, and fungi, are often absent.
The restoration of ecosystems like forests and wetlands can aid in the conservation of declining animal and plant species, facilitating their recovery. Nonetheless, recent research indicates that these species do not all return at the same pace. Some of the tiniest, least conspicuous inhabitants may remain scarce or missing for extended periods, potentially impacting other species.
Ellen Macdonald, a botanist at the University of Alberta, has dedicated her career to studying forests, focusing not on the trees themselves but on the minute flowers, mosses, liverworts, and lichens that thrive in their shadows, among their roots, or on their bark’s textured surfaces.
Macdonald explained that there are significantly more species in these areas than there are tree species. To the average observer, a reforested area a few decades post-logging may appear similar to one that has never been disturbed, teeming with tall trees, birds, and insects. However, Macdonald noted a sense of something amiss while walking through regenerated coniferous boreal forests, even if she couldn’t pinpoint it immediately.
She emphasized the need to collect data to truly discern what might be missing. Macdonald conducted a comprehensive study, merging her research with global data to analyze the time it takes for plants and animals to reestablish themselves as boreal forests regenerate following clear-cutting.
The study, recently featured in the journal Nature Sustainability, revealed that birch and aspen forests and their inhabitants typically recover within 25 years, while conifer forests require significantly longer. In conifer forests, understory plants, particularly lichens, mosses, and liverworts, may take 85 years or more to reappear, with some species still missing after a century.
The observed pattern is not exclusive to boreal forests. Researchers examining restored wetlands and other habitats have encountered similar scenarios where certain less conspicuous species remain absent despite the overall appearance of health.
Viktoria Wagner, an associate professor at the University of Alberta, described this decline as a “silent form of loss,” where species may not go extinct entirely but vanish from numerous locations, reducing the overall species richness at individual sites. Wagner identified this phenomenon as “dark diversity,” noting its prevalence among plants globally.
Wagner and her colleagues found that once species disappear from a specific area, their return may be challenging, with some potentially locally extinct. While landscape restoration is feasible, Wagner emphasized that it is a complex process with no guaranteed outcomes.
The absence of certain species can impede the recovery process and have unseen repercussions. Algae, despite their small size, play a crucial role in global oxygen production and food availability. Wagner highlighted the significance of species diversity in maintaining ecosystem balance and preventing cascading effects on other organisms.
Understanding these ecological patterns can guide landscape managers in preserving a broader array of species. Macdonald suggested that selective or partial harvesting of conifer forests, instead of clear-cutting, could help protect the diverse understory flora that takes decades to regenerate.
Algae habitats worldwide, along with their associated species, are under threat. Michael Melkonian, a German botanist, painstakingly collects and preserves various algae strains to safeguard their biodiversity. Melkonian’s efforts have resulted in the establishment of an “algal zoo” comprising over 5,000 strains, ensuring the preservation of these species as living organisms.
For Wagner, the ongoing loss of species underscores the necessity of maintaining and restoring sufficient habitats to support species persistence across landscapes. Active interventions are essential to counteract the continuous process of species loss and preserve biodiversity effectively.
