A study spanning more than two decades and some 30,000 observations suggests that the Azores’ protected native forests have offered remarkable resilience against the worldwide decline of insects and other arthropods. But seven rare endemic species may already have disappeared, reminding scientists that protection works only when it is accompanied by vigilance.
There are worlds beneath the Azorean forest that most human eyes never see. They move through the damp soil beneath laurel leaves, disappear into moss-covered trunks, climb through canopies touched by Atlantic mist and inhabit fragments of native forest that survived centuries of human transformation. Spiders, beetles and other arthropods may be small enough to escape our attention, yet together they help sustain the intricate machinery of an ecosystem. Now, after more than two decades of scientific observation, these almost invisible inhabitants are telling an unexpectedly hopeful story: where native forest has been rigorously protected, biodiversity can resist some of the decline being recorded elsewhere in the world.
Published in Scientific Reports, part of the Nature Portfolio, the international study “Stability in the Face of Global Decline: A 20-Year Study of Arthropods in an Oceanic Archipelago” brings together researchers from the University of the Azores and the Centre for Ecology, Evolution and Environmental Changes (CE3C) at the University of Lisbon’s Faculty of Sciences, working with international specialists. The research draws upon the long-running BALA project—Biodiversity of Arthropods from the Laurisilva of the Azores—and samples collected between 1999 and 2023.
The scale of the undertaking is remarkable for an archipelago of small Atlantic islands. Researchers monitored 30 standardized sites within 15 fragments of native forest distributed across seven Azorean islands, examining approximately 30,000 observations involving 405 arthropod species. Ninety-one of those species are endemic, belonging nowhere naturally but to the Azores. Scientists sampled life at different levels of the forest, using pitfall traps for ground-dwelling fauna and beating techniques to collect species inhabiting the tree canopy. In this way, year after year, an ecological biography of the forest slowly accumulated.
Against the troubling global background of declining insect and invertebrate populations, the Azorean results offer cautious encouragement. Approximately 55 percent of the species studied remained stable over time, while 17 percent increased and 28 percent experienced significant declines. The findings suggest that ecological deterioration is not inevitable when relatively pristine habitats receive strong legal protection. Native forest, in other words, is not simply scenery inherited from the islands’ distant past. It can function as a living sanctuary.
But sanctuary does not mean immunity. Seven rare endemic species were not detected again during the two decades of field sampling and are now regarded by the researchers as probably extinct. Other species—particularly some associated with the forest floor and others considered high conservation priorities—continue to show worrying losses. The broad stability of the community can therefore conceal individual tragedies. An ecosystem may appear resilient in aggregate while some of its most singular inhabitants quietly disappear.
Paulo Borges, a University of the Azores and CE3C researcher who coordinates the BALA project and is one of the study’s authors, describes the research as the synthesis of more than 25 years of fieldwork, laboratory analysis, taxonomic identification and international scientific collaboration. Its central lesson, he argues, is both hopeful and demanding: “Protecting native forest works, but it is not enough.” Long-term monitoring must continue, accompanied by targeted intervention for the species and habitats facing the greatest danger.
That may be the most important message emerging from these decades of patient observation. Conservation is sometimes imagined as the simple act of drawing a boundary around a landscape and leaving nature alone. The Azorean evidence suggests something more complicated. Legal protection can provide the essential refuge, but science must continue listening to what happens inside that refuge—identifying declines early, understanding their causes and acting before rarity becomes disappearance.
The native forests of the Azores are remnants of an older Atlantic world. Within them survive species shaped by isolation over immense stretches of evolutionary time, creatures whose entire planetary geography may amount to a few fragments of forest on a handful of volcanic islands.
Their resilience offers reason for hope. Their disappearances offer a warning.
And somewhere beneath the laurel canopy, among wet leaves and ancient roots, the smallest inhabitants of the Azores are delivering a very large lesson: protecting a forest is not merely preserving what remains of the past. It is giving the future somewhere to live.
Based on a Story in Diário Insular, José Lourenço-director. The photo os from https://www.lifeazoresnatura.eu/