What Landsat Sees in Vermont: Forest Damage, Algal Blooms and Crops From 400 Miles Up

Vermont, the Green Mountain State, is known for broad deciduous forests, patches of evergreens and the Green Mountains down its middle. Its maples are why "Vermont" on a bottle of pure maple syrup reads as a seal of quality — 36% of the nation's maple syrup comes from the state — and its trails and ski slopes make it a destination for recreation. But there is more to it than syrup and slopes.

The Landsat satellites have been recording Vermont's forests and landscape for decades, and thanks to the open-data policy of the USGS National Land Imaging (NLI) Program, the whole archive is free to researchers, land managers and the public.

Forest health

Landsat records many bands of the electromagnetic spectrum, including infrared and near-infrared light the human eye can't see. That lets it catch damage to forests from fire, disease or invasive insects that may be invisible from the ground — across wide areas where surveying on foot would be hard, dangerous or too expensive. Its long record lets scientists set baselines for forest health and project trends.

In Vermont, that use goes back decades: from a 1988 assessment of damage to high-elevation conifer forests in Vermont and New Hampshire to a 2020 projection of how southeastern Vermont's forests might change, with management strategies for a changing environment.

Algal blooms

The sensors that pick out damage to hemlock and maple leaves can also detect the chlorophyll of algae in water — which makes Landsat useful for tracking blooms of harmful cyanobacteria in Vermont's lakes and rivers, a threat to aquatic life and to human health. It images them from more than 400 miles up. A 2020 study combined Landsat images with field surveys to model where and how often cyanobacteria dominated in Lake Champlain, the kind of mapping that can guide efforts to limit blooms.

Burlington and Lake Champlain from Landsat 8, June 1, 2013: swirls of green algae in the lake. USGS

Farms and land use

• The Lake Champlain Basin Program, a multi-agency partnership, has used Landsat to map and monitor the watershed. To follow land-use change across the basin, it used modified data from the National Land Cover Database (NLCD) — a Landsat-based map that gives every 30-by-30-meter plot in the country a land-cover class such as pasture, developed land, cropland or deciduous forest.
• The U.S. Department of Agriculture relies on Landsat to build its National Agricultural Statistics Service Cropland Data Layer, an interactive map of the crops grown each year in every state.

USDA's CropScape, built on Landsat data, maps U.S. crops year after year, which helps reveal trends.

Landsat nationally

• Access. The National Land Imaging Program supplies satellite imagery and other remote-sensing and geospatial data to government, business, universities and the public; the program-funded USGS Earth Resources Observation and Science (EROS) Center gives worldwide access to Landsat data.
• Use. Landsat is the most widely used land remote-sensing source in federal civilian agencies, and local, state and Tribal agencies use it too, to monitor and forecast what happens on the land surface — informing daily decisions on land, water and resources that protect life and property, safeguard the environment, advance science and education and grow the economy. Businesses build customer applications on it, and commercial imaging firms use it to refine their products.
• Value. A 2024 study put Landsat's total annual economic benefit at $25.6 billion, far more than it costs to build and run.
• Coverage and the future. Landsat 8 and Landsat 9 together image Earth's land every 8 days. NASA and the USGS are working toward launching Landsat 10 in 2031, with significant improvements, to extend what is the world's longest record of Earth's land surface over time.

Consistent, accurate data over the long term, free to all, let users study large areas and long-term change — and new cloud computing and analytics tools now build Landsat into decision-support systems for government and industry. Like GPS and weather data, Landsat is used every day to understand a changing planet.

Sources

Based on "Vermont and Landsat," U.S. Geological Survey Fact Sheet 2021-3038, National Land Imaging Program; a work of the United States government in the public domain. The fact sheet dates the Landsat record as "54-plus" years in one place and "50-plus" in another, so no figure is given here; it also names Lake George and the Hudson River among Vermont's waters, which are left out.