NASA Helps Weed Our National Garden

When people think of NASA, they usually think of space exploration. But NASA also explores our home planet, and the results of that exploration help other agencies provide substantial benefits to our society and economy. An example of NASA’s Earth research leading to new benefits is in the area of the control of non-native plants such as the plants that may be reducing water supplies in the western United States.

NASA makes its earth observations, modeling and computational capabilities available to enhance the tools other agencies use to control invasive plant species. An “invasive species” is non-native (alien) to the ecosystem in which it’s found. Often, invasive species cause economic or environmental harm or harm to human health. Invasive species can be plants, animals, and other organisms (e.g., microbes). Human actions are the primary means of invasive species introductions.

Invasive plant species traditionally are located, identified and monitored by manual ground surveys. Such surveys are effective, but expensive, timely and difficult to manage over large areas. Now, a new tool developed by the U.S. Geological Survey (USGS) is taking advantage of observations from NASA satellites and NASA systems engineering to provide a service for land managers that predicts quickly and inexpensively the location and spread of invasive plants over regional areas. The tool, called the Invasive Species Forecasting System (ISFS) was recently used to make the first predictive map of tamarisk habitat in the United States.

Tamarisk is a large shrub to small tree native to Africa and Eurasia. It was introduced in the western U.S. in the early 1800s as “ornamental vegetation” and for wind and erosion control. Tamarisk has since spread and can be found from Minnesota to California and from Mexico to Canada. The U.S. Department of Agriculture recently identified tamarisk as one of the most harmful invasive species in the nation, because the plant’s long roots tap into underground aquifers. Its groundwater-absorbing qualities may be adding to the severity of the drought in the western U.S. Tamarisk also increases the salt concentration of the soil and degrades habitats for native species along river systems.

“The ISFS combines NASA satellite data with tens of thousands of field sampling measurements, which are then used to analyze past and present distributions of non-native plants and predict their future growth patterns,” said Tom Stohlgren, director of the USGS’ National Institute of Invasive Species Science (NIISS). Land managers and others can use the ISFS to generate color-coded maps to help predict and manage the spread of troublesome invasive species.

The ISFS uses observations and data products from NASA’s Terra, Aqua, and Earth Observing-1 satellites, and the USGS-operated Landsat satellites, together with field data from government and non-government contributors. All of these satellites observe and measure sunlight reflected by plants and the environments in which they are growing. The satellites are able to “lock in” on unique aspects of the reflected light to determine tamarisk’s current locations as well as habitats that are vulnerable to invasion.

During the blooming season for tamarisk, ISFS-generated maps predicting tamarisk locations matched observations of the plant in the field. These predictive maps are an important new tool for land managers involved with tamarisk-related control and restoration efforts. “Satellite data coupled with computer modeling helps us understand where tamarisk is likely to be growing, even in remote locations that field researchers cannot easily reach,” said John Schnase, principal investigator of the ISFS project at NASA’s Goddard Space Flight Center in Greenbelt, Md.

The ISFS uses invasive species occurrence and abundance data from the Global Organism Detection and Monitoring System developed by the USGS Fort Collins Science Center and Colorado State University. This monitoring system is an on-line database that allows people to report sightings of tamarisk or other invasive species to USGS scientists, who then review the observations and incorporate validated new data into ISFS map products.

Currently, USGS is using the ISFS to predict the distribution of other invasive species such as cheatgrass, Canadian star thistle, and certain aquatic species. “With this new technology USGS is significantly enhancing its ability to support invasive species management. The enhancements in the ISFS are the result of the use of NASA observations, model output, and systems engineering,” said Ed Sheffner, the program manager for invasive species in the Applied Sciences Program at NASA Headquarters in Washington.

NASA and USGS (through the Department of the Interior) are members of the National Invasive Species Council. It is an interdepartmental council with 13 cabinet-level member organizations. Formed by Executive Order in 1999, the council facilitates coordination and provides leadership for federal agencies working on invasive species issues.