A regenerated forest can appear tall, dense, and vibrant with greenery. Rejuvenated wetlands can be bustling with insects and alive with birds. However, upon closer examination, scientists are discovering that some of the tiniest inhabitants like certain mosses, lichens, algae, and fungi are often missing even in restored habitats.
The restoration of ecosystems such as forests and wetlands can aid in saving declining species of animals and plants and promote their population recovery. Nonetheless, recent studies indicate that the return of all species does not occur at the same pace. Some of the smallest, least conspicuous inhabitants may remain scarce or absent for decades, potentially impacting other species.
Ellen Macdonald, a botanist from 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 shadow, amidst their roots, or on the textured surfaces of their bark.
According to Macdonald, the number of species in these ecosystems far surpasses that of tree species. To the casual observer, a regenerated forest decades after logging may resemble an untouched one, abundant with tall trees, birds, and insects. However, Macdonald has observed a sense of discrepancy while walking through regrown coniferous boreal forests, hinting at the absence of certain elements that may not be immediately noticeable without data collection.
Macdonald conducted a study combining her research with global data to analyze the duration for plants and animals to repopulate as boreal forests recover post clearcutting. The research, recently published in the journal Nature Sustainability, revealed that birch and aspen forests and their inhabitants seem to recover within 25 years, whereas conifer forests take significantly longer. In conifer forests, understory plants, particularly lichens, mosses, and liverworts, required 85 years or more to reestablish, with some species still not recovered after a century of monitoring.
The phenomenon of certain less visible species remaining absent in seemingly healthy habitats is not exclusive to boreal forests. Researchers studying wetlands and other restored environments have encountered similar findings. German botanist Michael Melkonian described a scenario where restored wetlands were visually appealing yet lacked numerous desmid algae species previously abundant in the area.
Victoria Wagner, an associate professor at the University of Alberta, describes this decline as a “silent form of loss,” where species gradually disappear from their once-inhabited sites, diminishing overall species diversity. This phenomenon, known as “dark diversity,” has been observed among plants globally, including algae.
The absence of certain species may impede ecosystem recovery and have unseen repercussions. Algae, despite their small size, play a significant role in global oxygen availability and food production through photosynthesis. Consequently, declining diversity can have cascading effects on other species within the ecosystem.
Understanding these patterns can guide landscape managers in preserving a greater number of species. Macdonald suggests that selective or partial harvesting of conifer forests might be more beneficial than clearcutting, based on the research findings.
Melkonian highlighted the threat to algae habitats worldwide and the imperative to preserve these species. His efforts, alongside colleagues, involve collecting and cultivating thousands of algae strains to safeguard their existence.
Wagner emphasizes that biodiversity conservation demands more than safeguarding isolated habitats; it necessitates maintaining and restoring adequate habitat to ensure species survival across landscapes. She asserts that loss of species is an ongoing process requiring active interventions to mitigate its impact and ensure species persistence.
This article is part of a series shedding light on the work of scientists investigating disappearing species groups that often go unnoticed, emphasizing their significance and the actions needed to protect them.