American Forests That Have Lost The Most Trees

The world’s forests are shrinking. TIME recently published a series titled “Why The Amazon Rain Forest Is Almost Gone,” while The Washington Post warned that deforestation brings the Amazon closer each day to what scientists call its “death”—the point of no return when loss of tree cover causes the world to lose its greatest shield against rising temperatures. The Amazon Rain Forest, the largest tropical rainforest in the world, faces destruction driven almost entirely by human activities, including deforestation for farming, logging, and wildfires.

US forests have suffered similar fates. Many have lost substantial tree cover primarily due to destructive human activities and climate-related factors. In Tongass National Forest, the primary culprit is spruce beetles, which have spread rapidly due to global warming. Pine beetles have similarly devastated trees in Pike National Forest and White River National Forest.

According to the USGS, “Temperature increases caused by climate change were a major factor driving the outbreak of mountain pine beetles that killed whitebark pine across millions of acres in and around Yellowstone National Park.”

Wildfires represent another major cause of forest destruction. Last year, the National Interagency Fire Center reported that last year 64,897 wildfires destroyed 8,924,884 acres. This year alone, the Dragon Bravo Fire in the Grand Canyon burned over 145,000 acres, the Gifford Fire in California burned 131,000 acres, and the Lee Fire in Colorado burned 137,000 acres. Of the ten forests that have lost the most trees, six list wildfires as a major cause.

Drought is a primary driver of these wildfires, and extreme drought—particularly in the American West—has been intensified by global warming. The Center for Climate and Energy Solutions reports that “Climate change increases the odds of worsening drought in many parts of the United States and the world. Regions such as the U.S. Southwest, where droughts are expected to get more frequent, intense, and longer lasting, are at particular risk.”

As global temperatures continue to rise, the causes of shrinking forests will only worsen.

These forests and national parks have experienced the most significant tree loss in recent years (last decade), based on the largest absolute or visible loss:

• Tongass National Forest (Alaska): Spruce beetle infestations, yellow-cedar die-off, and wind damage have caused the biggest single forest loss in the country.

• Sierra National Forest and Sequoia National Forest (California) — Megafires in 2020–2021 destroyed hundreds of thousands of giant sequoias.

• Klamath National Forest (California): Fires from 2020–2022, including the August Complex Fire, burned huge patches almost completely.

• Pike National Forest (Colorado): Mountain pine beetles killed millions of pines, turning whole mountainsides red, then gray.

• White River National Forest (Colorado): Pine beetle infestations and major fires have left visible dead stands everywhere.

• Chugach National Forest (Alaska): Spruce beetle infestations and climate stress have made this the second-biggest loss in Alaska.

• Angeles National Forest (California): The Bobcat Fire and Station Fire aftermath left huge brown scars close to Los Angeles.

• Tahoe National Forest (California): The 2021 Caldor Fire burned nearly half the forest severely.

• Okanogan-Wenatchee National Forest (Washington): Wildfires from 2014–2021 left very large areas still blackened.

• Pisgah and Nantahala National Forests (North Carolina): The hemlock woolly adelgid killed almost all hemlocks, leaving entire valleys without these trees.

Sources for the List of US Forests with Significant Tree Loss

Data on individual forests with the most notable recent tree loss (2000–2025) comes from a synthesis of satellite monitoring (primarily Global Forest Watch/University of Maryland tree cover loss datasets), USDA Forest Service reports on insect and disease outbreaks and wildfires, National Park Service assessments, NASA, the Department of Agriculture, and peer-reviewed studies. These sources highlight absolute or ecologically significant losses from wildfires, bark beetles, and other insects during the 2000–2025 period. Tree loss refers to mortality or removal, often resulting in visible die-off or burning.

Rankings are approximate based on visible and ecological impact and absolute area affected; the exact measurement of “most trees lost” varies by metric. Many areas are regrowing or being managed, but old-growth losses are often irreversible in the short term.