[From the Director] As we watch the rapid disappearance of forests around the world, it’s hard to ignore the growing phenomenon of “ghost forests”—areas once humming with biodiversity, now falling silent. But amidst this crisis, there’s a story of resilience and hope in northeastern Peru. At the Morpho Institute, we’re partnering with OnePlanet and the Indigenous Maijuna to not only conserve what remains of their vital Amazon forests but to bring back what was lost. The journey is one of healing—restoring both land and culture after the devastating impact of logging and poaching in the 1990s. What started as a battle for survival has now blossomed into a beacon of sustainable conservation and education.
To help provide a deeper context, we’ve asked Dr. David Pearson to explain the concept of a ‘ghost forest’ in this special blog post. Dave has worked around the world on issues of tropical biodiversity, conservation, and education. We are so glad to have him on our team! #themoreyouknow #smartereveryday
Amazonian Ghost Forests: How do Indigenous cultures and modern technology intertwine for conservation and management?
Dr. David Pearson, School of Life Sciences, Arizona State University
What is a ghost forest? It is any forest that has lost its vitality, whether it is a few otherwise obvious species that have disappeared, or the entire forest is withering away like gray skeletons. How widespread are these reduced forests and how did it happen? Just as importantly, who oversees pulling these forests back from their gravesides, and how (Benítez-López et al. 2009, de Oliveira et al. 2018)?
It is easy to imagine the original Amazon, one of the most vibrant and species rich forests in the world, as a pristine habitat untouched for thousands of years by humans, except for a few small tribes of Indigenous people. And now discoveries of oil, gold, and ever-increasing pressure for lumbering, agricultural crops, cattle, and cheap expansion of cities seem to have pulled much of the Amazon into the ghost category. Recent estimates of tropical forests show that only 20% of the remaining area is considered intact (Laurence et al. 2002). The villains here are obvious, but the heroes that could teach us how to avoid this catastrophe are almost forgotten.
Perhaps we need to reconsider our image of the original Amazon. When Franciso de Orellano led the first European expedition down the Amazon in 1541, he encountered frequent opposition from Indigenous people living along the length of the river. Father Gaspar de Carvajal, his assistant, recorded large cities, well developed roads, fortified towns, and dense populations that he estimated in the 100’s of thousands if not millions. However, the next visit by Europeans in 1637 found few people living along the river, and for hundreds of years the reports by Orellano and Carvajal were dismissed as fabricated (Levy 2022).
Paradoxically, recent clearing of this forest has revealed the outlines (geoglyphs) of vast cities, roads, and agriculture going back 1000’s of years (Fig. 1). The latest technology, such as Lidar, uses a laser to create 3D maps of the Earth’s surface through the cover of thick vegetation like forest trees. These laser records reveal even more ancient civilizations in the forests not yet cleared (Fig. 2), and the discounted reports of Orellano and Carvajal were vindicated. The subsequent 16th and 17th Century reports of few people living along the Amazon were the result of disease epidemics introduced by Orellano and his men that quickly wiped out most of the original civilizations there (Newson 1996).
Now archaeologists have used these technological advances to assemble even more enlightening details about ancient Amazonian civilizations. Yes, there were large populations, cities, roads, and agriculture, but somehow these civilizations maintained the surrounding forests and their other inhabitants without “ghosting” them. How?
One answer is in patches of fertile black soil around these ancient sites. They are called terra preta, Portuguese for black soil. It stands out in stark contrast to the nutrient-poor, reddish, laterite soil that dominates the Amazon basin (Fig. 3). Collaborating with Indigenous partners, archeologists and anthropologists have gathered evidence that suggests the ancient Amazonians deliberately formed the rich soil patches thousands of years ago to fertilize their crops. They added carbon from campfires, discarded vegetation, fruits, and other organic material to produce dark soil with elevated levels of organic carbon, phosphorus, nitrogen, and calcium (Fig. 4) –– what we today call composting. Bacteria and other soil microbes inhabit these patches and help retain their beneficial chemical composition for centuries with no further human maintenance (Glaser and Birk 2012).
In addition to soil modification, pre-Colombian Indigenous people in the Amazon subtly but effectively modified the forest to benefit their survival by “(1) removal of non-useful plants, (2) protection of useful plants, (3) attraction of non-human animal seed dispersers and pollinators, (4) transportation of useful plants, (5) selection of seeds from plant individuals with the most desirable characteristics, (6) fire management, (7) and planting useful plants” (Levis et al. 2023).
But these ancient people also hunted meat to feed themselves. Perhaps because of the efficiency of land use and crop harvesting, the forest was not fragmented, and their hunting was not so intense that it drastically impacted animal populations (Milner-Gulland and Bennett 2003).
Centuries ago, the forest was intact and continuous. Today subsistence game hunting often has negative effects on biodiversity in the remaining Amazonian forests that appear undisturbed but are severely fragmented, especially by legal and illegal roads (Engert et al. 2024). These fragments are more accessible to hunters, permit little movement of animals from the few remaining unharvested source populations, and have reduced food availability for the frugivore–granivore vertebrate fauna (Peres 2001, Laurence et al. 2002). Notably the first animals impacted and locally extirpated on these fragments by subsistence hunting are large mammals and birds (Cardillo et al. 2005). These ghost forests can look pristine but have severely reduced or extirpated populations of large species like howler monkeys, tapirs, and macaws.
Determining just how much these large animal populations are reduced in a forest area is a major priority for conservation efforts and habitat management. Factors such as shyness, migration, normal population cycles, and detectability can make this process difficult and unreliable (Ewers and Didham 2006). In the 1890’s, the first trail camera used massive flashing cameras and tripwires to detect forest species. By the 1980’s field cameras had become much smaller, and eventually motion detectors and long-life batteries made them even more effective in discovering skulking species (Randin et al. 2020). But use of environmental DNA will likely soon make field cameras obsolete. At first, sampling DNA from scat was tried, but that had obvious limitations (Quasim et al. 2018). Then DNA from water samples within the forest (Rodgers and Mock 2015) and swabbing leaves (Lyngaard et al. 2023) gave more effective results. Now samples of DNA from skin cells, feather fragments, insect scales, and other organic material floating in the air can be collected to accurately detect and identify the local presence of large numbers of animal species within a few days rather than weeks, months, or years using cameras (Lyngaard et al. 2022).
In a time of growing ghost forests, the Morpho Institute is working together with OnePlanet and the Maijuna Community of northeastern Peru to develop useful education, conservation, and management practices to maintain forests and their biodiversity and even recover some that were lost. In the early 1990’s, logging companies began cutting down their forest and overhunting the animals of the area. This devastation so disrupted the lives of these Indigenous people that many were on the brink of starvation. With help from lawyers and concerned politicians, the Peruvian government was convinced to eject the logging company, and in 2015 the Maijuna were granted legal control of their homeland, the 4,000 Km2 Maijuna–Kichwa Regional Conservation Area. They studied their ancestors’ techniques and adapted them to modern methods of resource sustainability and wildlife management. Slowly they began to return the forest and its inhabitants to a semblance of what it was before (Gilmore 2005, Gilmore and Young 2010, 2012).
Their efforts to recover ghost forests include: the Aguaje Palm Project that helped conserve these native trees and make their fruits a sustainable and economic part of their culture. The Stingless Bee Project used native bees to develop their honey as a commercially valuable product. Hunters were provided GPS units so that by mapping the area they could avoid sites that other hunters had used recently. With trail cameras, rare wildlife was detected, and their places of occurrence were put off limits to hunting (van Vliet et al. 2015). Tourists were invited to visit the closer villages and learn of these conservation efforts as well as purchase souvenirs made by the Maijuna people. These communities have begun the complicated process of intertwining their cultural history, modern management practices, innovative technology, and education (Evans et al. 2020) to beat back many of the ghosts from their forest. At the same time, they are providing a model for other Indigenous communities in the Amazon facing their own ghost forest problems.
David L. Pearson, School of Life Sciences, Arizona State University, Tempe, AZ 85282
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David L. Pearson, School of Life Sciences, Arizona State University, Tempe, AZ 85282