Protecting Giant Trees Key to Peru's Net-Zero Future, Study Urges Policy Overhaul

A recent study published in Frontiers in Forests and Global Change highlights a critical need for Peru's national forest regulations to undergo substantial review if the country is to meet its ambitious net-zero emissions target by 2050. The research strongly suggests that the largest trees in the Peruvian Amazon require priority protection, a finding that may also be relevant for other nations across the region.

Dr. Geomar Vallejos-Torres, a principal investigator at the National University of San Martín, Peru, and corresponding author of the study, underscored the urgency of the situation.

"Felling trees with a diameter at breast height (DBH) of at least 41cm, depending on species, releases disproportionately large amounts of carbon into the atmosphere. This makes achieving net-zero goals difficult or impossible. Protecting these trees would also support biodiversity and forest microfauna, helping to buffer forest microclimates against future climate change."

Peru's Forest Landscape and Ongoing Pressure

Peru boasts the world's ninth-largest forest cover and the second largest within the Amazon basin. These vital ecosystems store approximately 6.9 million tons of CO2 equivalents above ground in the Peruvian Amazon. Despite this immense natural carbon sink, 150,602 hectares of Amazonian forest were lost in 2024 alone, signaling ongoing and significant pressure on these invaluable ecosystems.

Counterproductive Current Policy

Current official forest policy in Peru permits tree harvesting once a minimum DBH is reached. In the Peruvian Amazon, this threshold typically ranges from 41 to 61cm, varying by species. Crucially, this existing policy inadvertently prioritizes the selective logging of the very largest trees, a practice the new study deems counterproductive to climate goals.

The Study: Unveiling Carbon Storage Dynamics

The research, led by Vallejos-Torres and his colleagues, sought to pinpoint which trees store the most carbon across five representative forests in the San Martín department of the northern Peruvian Amazon: Ojos de Agua, Huallaga, Bajo Huallaga, Alto Mayo, and Alto Roque.

These diverse forests span a combined area of 3,802 km², with elevations ranging from 382 to 2,086 meters above sea level. Researchers meticulously examined 100 sampling plots, each 500 m², and measured 535 trees. Key variables such as diameter, height, crown area, and wood density were recorded to accurately estimate both above-ground and below-ground biomass, and subsequently, stored carbon.

Key Findings

Biodiversity and Carbon Density: Each forest surveyed contained between five and 18 tree species, contributing to a total of 59 species across all plots. Tree biodiversity was highest in Alto Mayo and lowest in Bajo Huallaga and Alto Roque. The Huallaga forest emerged with the highest carbon densities, storing 331.06 tons per hectare of above-ground carbon and 47.41 tons per hectare of below-ground carbon. In contrast, Alto Mayo showed the lowest values at 86.83 tons per hectare above-ground and 15.18 tons per hectare below-ground.
Disproportionate Carbon Storage in Large Trees: The research conclusively identified that carbon stocks increase disproportionately with increasing trunk diameter for most species, both above-ground and below-ground. A tree reaching at least 41cm DBH was identified as a key indicator of substantial carbon storage.
- For instance, Brosimum alicastrum stored an astonishing 88.6% of its total above-ground carbon in trees above this 41cm DBH threshold.
- Similarly, Manilkara bidentata concentrated 92.1% of its below-ground carbon in trees wider than 41cm.

Across the studied forests, carbon storage reached up to 331 tons per hectare above-ground and 47 tons per hectare below-ground. The vast majority, between 88% and 93% of total carbon, was concentrated within the largest trees. When considering only these large trees, the main forest species analyzed stored approximately 198 tons of carbon per hectare above-ground and 30 tons per hectare below-ground, underscoring their critical role in the overall forest carbon balance.

Urgent Call for Policy Change

The authors' conclusions are clear: Peru's current regulations are counterproductive, actively prioritizing the logging of trees that are paramount for carbon storage. They strongly recommend modifying forest policies to prioritize the protection of these large trees as a fundamental condition for Peru to successfully achieve its net-zero emissions by 2050 target.

Vallejos-Torres reiterated the vital importance of these giants: "These largest trees are not expendable but are essential for climate solutions."